Merge pull request #55950 from Faless/mp/4.x_replication_nodes

32 files changed, 2511 insertions, 1212 deletions

diff --git a/core/multiplayer/multiplayer_api.cpp b/core/multiplayer/multiplayer_api.cpp
index 627825246a..41d6d14696 100644
--- a/core/multiplayer/multiplayer_api.cpp
+++ b/core/multiplayer/multiplayer_api.cpp
@@ -32,7 +32,6 @@
 
 #include "core/debugger/engine_debugger.h"
 #include "core/io/marshalls.h"
-#include "core/multiplayer/multiplayer_replicator.h"
 #include "core/multiplayer/rpc_manager.h"
 #include "scene/main/node.h"
 
@@ -42,6 +41,8 @@
 #include "core/os/os.h"
 #endif
 
+MultiplayerReplicationInterface *(*MultiplayerAPI::create_default_replication_interface)(MultiplayerAPI *p_multiplayer) = nullptr;
+
 #ifdef DEBUG_ENABLED
 void MultiplayerAPI::profile_bandwidth(const String &p_inout, int p_size) {
 	if (EngineDebugger::is_profiling("multiplayer")) {
@@ -74,7 +75,7 @@ void MultiplayerAPI::poll() {
 		Error err = multiplayer_peer->get_packet(&packet, len);
 		if (err != OK) {
 			ERR_PRINT("Error getting packet!");
-			break; // Something is wrong!
+			return; // Something is wrong!
 		}
 
 		remote_sender_id = sender;
@@ -82,16 +83,13 @@ void MultiplayerAPI::poll() {
 		remote_sender_id = 0;
 
 		if (!multiplayer_peer.is_valid()) {
-			break; // It's also possible that a packet or RPC caused a disconnection, so also check here.
+			return; // It's also possible that a packet or RPC caused a disconnection, so also check here.
 		}
 	}
-	if (multiplayer_peer.is_valid() && multiplayer_peer->get_connection_status() == MultiplayerPeer::CONNECTION_CONNECTED) {
-		replicator->poll();
-	}
+	replicator->on_network_process();
 }
 
 void MultiplayerAPI::clear() {
-	replicator->clear();
 	connected_peers.clear();
 	path_get_cache.clear();
 	path_send_cache.clear();
@@ -133,6 +131,7 @@ void MultiplayerAPI::set_multiplayer_peer(const Ref<MultiplayerPeer> &p_peer) {
 		multiplayer_peer->connect("connection_failed", callable_mp(this, &MultiplayerAPI::_connection_failed));
 		multiplayer_peer->connect("server_disconnected", callable_mp(this, &MultiplayerAPI::_server_disconnected));
 	}
+	replicator->on_reset();
 }
 
 Ref<MultiplayerPeer> MultiplayerAPI::get_multiplayer_peer() const {
@@ -167,13 +166,13 @@ void MultiplayerAPI::_process_packet(int p_from, const uint8_t *p_packet, int p_
 			_process_raw(p_from, p_packet, p_packet_len);
 		} break;
 		case NETWORK_COMMAND_SPAWN: {
-			replicator->process_spawn_despawn(p_from, p_packet, p_packet_len, true);
+			replicator->on_spawn_receive(p_from, p_packet, p_packet_len);
 		} break;
 		case NETWORK_COMMAND_DESPAWN: {
-			replicator->process_spawn_despawn(p_from, p_packet, p_packet_len, false);
+			replicator->on_despawn_receive(p_from, p_packet, p_packet_len);
 		} break;
 		case NETWORK_COMMAND_SYNC: {
-			replicator->process_sync(p_from, p_packet, p_packet_len);
+			replicator->on_sync_receive(p_from, p_packet, p_packet_len);
 		} break;
 	}
 }
@@ -324,7 +323,7 @@ bool MultiplayerAPI::_send_confirm_path(Node *p_node, NodePath p_path, PathSentC
 #define ENCODE_16 1 << 5
 #define ENCODE_32 2 << 5
 #define ENCODE_64 3 << 5
-Error MultiplayerAPI::encode_and_compress_variant(const Variant &p_variant, uint8_t *r_buffer, int &r_len) {
+Error MultiplayerAPI::encode_and_compress_variant(const Variant &p_variant, uint8_t *r_buffer, int &r_len, bool p_allow_object_decoding) {
 	// Unreachable because `VARIANT_MAX` == 27 and `ENCODE_VARIANT_MASK` == 31
 	CRASH_COND(p_variant.get_type() > VARIANT_META_TYPE_MASK);
 
@@ -385,7 +384,7 @@ Error MultiplayerAPI::encode_and_compress_variant(const Variant &p_variant, uint
 		} break;
 		default:
 			// Any other case is not yet compressed.
-			Error err = encode_variant(p_variant, r_buffer, r_len, allow_object_decoding);
+			Error err = encode_variant(p_variant, r_buffer, r_len, p_allow_object_decoding);
 			if (err != OK) {
 				return err;
 			}
@@ -399,7 +398,7 @@ Error MultiplayerAPI::encode_and_compress_variant(const Variant &p_variant, uint
 	return OK;
 }
 
-Error MultiplayerAPI::decode_and_decompress_variant(Variant &r_variant, const uint8_t *p_buffer, int p_len, int *r_len) {
+Error MultiplayerAPI::decode_and_decompress_variant(Variant &r_variant, const uint8_t *p_buffer, int p_len, int *r_len, bool p_allow_object_decoding) {
 	const uint8_t *buf = p_buffer;
 	int len = p_len;
 
@@ -458,7 +457,7 @@ Error MultiplayerAPI::decode_and_decompress_variant(Variant &r_variant, const ui
 			}
 		} break;
 		default:
-			Error err = decode_variant(r_variant, p_buffer, p_len, r_len, allow_object_decoding);
+			Error err = decode_variant(r_variant, p_buffer, p_len, r_len, p_allow_object_decoding);
 			if (err != OK) {
 				return err;
 			}
@@ -467,17 +466,84 @@ Error MultiplayerAPI::decode_and_decompress_variant(Variant &r_variant, const ui
 	return OK;
 }
 
+Error MultiplayerAPI::encode_and_compress_variants(const Variant **p_variants, int p_count, uint8_t *p_buffer, int &r_len, bool *r_raw, bool p_allow_object_decoding) {
+	r_len = 0;
+	int size = 0;
+
+	if (p_count == 0) {
+		if (r_raw) {
+			*r_raw = true;
+		}
+		return OK;
+	}
+
+	// Try raw encoding optimization.
+	if (r_raw && p_count == 1) {
+		*r_raw = false;
+		const Variant &v = *(p_variants[0]);
+		if (v.get_type() == Variant::PACKED_BYTE_ARRAY) {
+			*r_raw = true;
+			const PackedByteArray pba = v;
+			if (p_buffer) {
+				memcpy(p_buffer, pba.ptr(), pba.size());
+			}
+			r_len += pba.size();
+		} else {
+			encode_and_compress_variant(v, p_buffer, size, p_allow_object_decoding);
+			r_len += size;
+		}
+		return OK;
+	}
+
+	// Regular encoding.
+	for (int i = 0; i < p_count; i++) {
+		const Variant &v = *(p_variants[i]);
+		encode_and_compress_variant(v, p_buffer ? p_buffer + r_len : nullptr, size, p_allow_object_decoding);
+		r_len += size;
+	}
+	return OK;
+}
+
+Error MultiplayerAPI::decode_and_decompress_variants(Vector<Variant> &r_variants, const uint8_t *p_buffer, int p_len, int &r_len, bool p_raw, bool p_allow_object_decoding) {
+	r_len = 0;
+	int argc = r_variants.size();
+	if (argc == 0 && p_raw) {
+		return OK;
+	}
+	ERR_FAIL_COND_V(p_raw && argc != 1, ERR_INVALID_DATA);
+	if (p_raw) {
+		r_len = p_len;
+		PackedByteArray pba;
+		pba.resize(p_len);
+		memcpy(pba.ptrw(), p_buffer, p_len);
+		r_variants.write[0] = pba;
+		return OK;
+	}
+
+	Vector<Variant> args;
+	Vector<const Variant *> argp;
+	args.resize(argc);
+
+	for (int i = 0; i < argc; i++) {
+		ERR_FAIL_COND_V_MSG(r_len >= p_len, ERR_INVALID_DATA, "Invalid packet received. Size too small.");
+
+		int vlen;
+		Error err = MultiplayerAPI::decode_and_decompress_variant(r_variants.write[i], &p_buffer[r_len], p_len - r_len, &vlen, p_allow_object_decoding);
+		ERR_FAIL_COND_V_MSG(err != OK, err, "Invalid packet received. Unable to decode state variable.");
+		r_len += vlen;
+	}
+	return OK;
+}
+
 void MultiplayerAPI::_add_peer(int p_id) {
 	connected_peers.insert(p_id);
 	path_get_cache.insert(p_id, PathGetCache());
-	if (is_server()) {
-		replicator->spawn_all(p_id);
-	}
+	replicator->on_peer_change(p_id, true);
 	emit_signal(SNAME("peer_connected"), p_id);
 }
 
 void MultiplayerAPI::_del_peer(int p_id) {
-	connected_peers.erase(p_id);
+	replicator->on_peer_change(p_id, false);
 	// Cleanup get cache.
 	path_get_cache.erase(p_id);
 	// Cleanup sent cache.
@@ -488,6 +554,7 @@ void MultiplayerAPI::_del_peer(int p_id) {
 		PathSentCache *psc = path_send_cache.getptr(E);
 		psc->confirmed_peers.erase(p_id);
 	}
+	connected_peers.erase(p_id);
 	emit_signal(SNAME("peer_disconnected"), p_id);
 }
 
@@ -500,6 +567,7 @@ void MultiplayerAPI::_connection_failed() {
 }
 
 void MultiplayerAPI::_server_disconnected() {
+	replicator->on_reset();
 	emit_signal(SNAME("server_disconnected"));
 }
 
@@ -612,14 +680,26 @@ bool MultiplayerAPI::is_object_decoding_allowed() const {
 	return allow_object_decoding;
 }
 
-void MultiplayerAPI::scene_enter_exit_notify(const String &p_scene, Node *p_node, bool p_enter) {
-	replicator->scene_enter_exit_notify(p_scene, p_node, p_enter);
-}
-
 void MultiplayerAPI::rpcp(Node *p_node, int p_peer_id, const StringName &p_method, const Variant **p_arg, int p_argcount) {
 	rpc_manager->rpcp(p_node, p_peer_id, p_method, p_arg, p_argcount);
 }
 
+Error MultiplayerAPI::spawn(Object *p_object, Variant p_config) {
+	return replicator->on_spawn(p_object, p_config);
+}
+
+Error MultiplayerAPI::despawn(Object *p_object, Variant p_config) {
+	return replicator->on_despawn(p_object, p_config);
+}
+
+Error MultiplayerAPI::replication_start(Object *p_object, Variant p_config) {
+	return replicator->on_replication_start(p_object, p_config);
+}
+
+Error MultiplayerAPI::replication_stop(Object *p_object, Variant p_config) {
+	return replicator->on_replication_stop(p_object, p_config);
+}
+
 void MultiplayerAPI::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_root_node", "node"), &MultiplayerAPI::set_root_node);
 	ClassDB::bind_method(D_METHOD("get_root_node"), &MultiplayerAPI::get_root_node);
@@ -638,14 +718,12 @@ void MultiplayerAPI::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("is_refusing_new_connections"), &MultiplayerAPI::is_refusing_new_connections);
 	ClassDB::bind_method(D_METHOD("set_allow_object_decoding", "enable"), &MultiplayerAPI::set_allow_object_decoding);
 	ClassDB::bind_method(D_METHOD("is_object_decoding_allowed"), &MultiplayerAPI::is_object_decoding_allowed);
-	ClassDB::bind_method(D_METHOD("get_replicator"), &MultiplayerAPI::get_replicator);
 
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "allow_object_decoding"), "set_allow_object_decoding", "is_object_decoding_allowed");
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "refuse_new_connections"), "set_refuse_new_connections", "is_refusing_new_connections");
 	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "multiplayer_peer", PROPERTY_HINT_RESOURCE_TYPE, "MultiplayerPeer", PROPERTY_USAGE_NONE), "set_multiplayer_peer", "get_multiplayer_peer");
 	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "root_node", PROPERTY_HINT_RESOURCE_TYPE, "Node", PROPERTY_USAGE_NONE), "set_root_node", "get_root_node");
 	ADD_PROPERTY_DEFAULT("refuse_new_connections", false);
-	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "replicator", PROPERTY_HINT_RESOURCE_TYPE, "MultiplayerReplicator", PROPERTY_USAGE_NONE), "", "get_replicator");
 
 	ADD_SIGNAL(MethodInfo("peer_connected", PropertyInfo(Variant::INT, "id")));
 	ADD_SIGNAL(MethodInfo("peer_disconnected", PropertyInfo(Variant::INT, "id")));
@@ -656,13 +734,16 @@ void MultiplayerAPI::_bind_methods() {
 }
 
 MultiplayerAPI::MultiplayerAPI() {
-	replicator = memnew(MultiplayerReplicator(this));
+	if (create_default_replication_interface) {
+		replicator = Ref<MultiplayerReplicationInterface>(create_default_replication_interface(this));
+	} else {
+		replicator.instantiate();
+	}
 	rpc_manager = memnew(RPCManager(this));
 	clear();
 }
 
 MultiplayerAPI::~MultiplayerAPI() {
 	clear();
-	memdelete(replicator);
 	memdelete(rpc_manager);
 }
diff --git a/core/multiplayer/multiplayer_api.h b/core/multiplayer/multiplayer_api.h
index 713035428d..f4fdafc323 100644
--- a/core/multiplayer/multiplayer_api.h
+++ b/core/multiplayer/multiplayer_api.h
@@ -35,7 +35,26 @@
 #include "core/multiplayer/multiplayer_peer.h"
 #include "core/object/ref_counted.h"
 
-class MultiplayerReplicator;
+class MultiplayerAPI;
+
+class MultiplayerReplicationInterface : public RefCounted {
+	GDCLASS(MultiplayerReplicationInterface, RefCounted);
+
+public:
+	virtual void on_peer_change(int p_id, bool p_connected) {}
+	virtual void on_reset() {}
+	virtual Error on_spawn_receive(int p_from, const uint8_t *p_buffer, int p_buffer_len) { return ERR_UNAVAILABLE; }
+	virtual Error on_despawn_receive(int p_from, const uint8_t *p_buffer, int p_buffer_len) { return ERR_UNAVAILABLE; }
+	virtual Error on_sync_receive(int p_from, const uint8_t *p_buffer, int p_buffer_len) { return ERR_UNAVAILABLE; }
+	virtual Error on_spawn(Object *p_obj, Variant p_config) { return ERR_UNAVAILABLE; }
+	virtual Error on_despawn(Object *p_obj, Variant p_config) { return ERR_UNAVAILABLE; }
+	virtual Error on_replication_start(Object *p_obj, Variant p_config) { return ERR_UNAVAILABLE; }
+	virtual Error on_replication_stop(Object *p_obj, Variant p_config) { return ERR_UNAVAILABLE; }
+	virtual void on_network_process() {}
+
+	MultiplayerReplicationInterface() {}
+};
+
 class RPCManager;
 
 class MultiplayerAPI : public RefCounted {
@@ -95,7 +114,7 @@ private:
 	Node *root_node = nullptr;
 	bool allow_object_decoding = false;
 
-	MultiplayerReplicator *replicator = nullptr;
+	Ref<MultiplayerReplicationInterface> replicator;
 	RPCManager *rpc_manager = nullptr;
 
 protected:
@@ -108,6 +127,13 @@ protected:
 	void _process_raw(int p_from, const uint8_t *p_packet, int p_packet_len);
 
 public:
+	static MultiplayerReplicationInterface *(*create_default_replication_interface)(MultiplayerAPI *p_multiplayer);
+
+	static Error encode_and_compress_variant(const Variant &p_variant, uint8_t *p_buffer, int &r_len, bool p_allow_object_decoding);
+	static Error decode_and_decompress_variant(Variant &r_variant, const uint8_t *p_buffer, int p_len, int *r_len, bool p_allow_object_decoding);
+	static Error encode_and_compress_variants(const Variant **p_variants, int p_count, uint8_t *p_buffer, int &r_len, bool *r_raw = nullptr, bool p_allow_object_decoding = false);
+	static Error decode_and_decompress_variants(Vector<Variant> &r_variants, const uint8_t *p_buffer, int p_len, int &r_len, bool p_raw = false, bool p_allow_object_decoding = false);
+
 	void poll();
 	void clear();
 	void set_root_node(Node *p_node);
@@ -117,13 +143,13 @@ public:
 
 	Error send_bytes(Vector<uint8_t> p_data, int p_to = MultiplayerPeer::TARGET_PEER_BROADCAST, Multiplayer::TransferMode p_mode = Multiplayer::TRANSFER_MODE_RELIABLE, int p_channel = 0);
 
-	Error encode_and_compress_variant(const Variant &p_variant, uint8_t *p_buffer, int &r_len);
-	Error decode_and_decompress_variant(Variant &r_variant, const uint8_t *p_buffer, int p_len, int *r_len);
-
 	// Called by Node.rpc
 	void rpcp(Node *p_node, int p_peer_id, const StringName &p_method, const Variant **p_arg, int p_argcount);
-	// Called by Node._notification
-	void scene_enter_exit_notify(const String &p_scene, Node *p_node, bool p_enter);
+	// Replication API
+	Error spawn(Object *p_object, Variant p_config);
+	Error despawn(Object *p_object, Variant p_config);
+	Error replication_start(Object *p_object, Variant p_config);
+	Error replication_stop(Object *p_object, Variant p_config);
 	// Called by replicator
 	bool send_confirm_path(Node *p_node, NodePath p_path, int p_target, int &p_id);
 	Node *get_cached_node(int p_from, uint32_t p_node_id);
@@ -148,7 +174,6 @@ public:
 	void set_allow_object_decoding(bool p_enable);
 	bool is_object_decoding_allowed() const;
 
-	MultiplayerReplicator *get_replicator() const { return replicator; }
 	RPCManager *get_rpc_manager() const { return rpc_manager; }
 
 #ifdef DEBUG_ENABLED
diff --git a/core/multiplayer/multiplayer_replicator.cpp b/core/multiplayer/multiplayer_replicator.cpp
deleted file mode 100644
index e7de8219c7..0000000000
--- a/core/multiplayer/multiplayer_replicator.cpp
+++ /dev/null
@@ -1,791 +0,0 @@
-/*************************************************************************/
-/*  multiplayer_replicator.cpp                                           */
-/*************************************************************************/
-/*                       This file is part of:                           */
-/*                           GODOT ENGINE                                */
-/*                      https://godotengine.org                          */
-/*************************************************************************/
-/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
-/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
-/*                                                                       */
-/* Permission is hereby granted, free of charge, to any person obtaining */
-/* a copy of this software and associated documentation files (the       */
-/* "Software"), to deal in the Software without restriction, including   */
-/* without limitation the rights to use, copy, modify, merge, publish,   */
-/* distribute, sublicense, and/or sell copies of the Software, and to    */
-/* permit persons to whom the Software is furnished to do so, subject to */
-/* the following conditions:                                             */
-/*                                                                       */
-/* The above copyright notice and this permission notice shall be        */
-/* included in all copies or substantial portions of the Software.       */
-/*                                                                       */
-/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
-/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
-/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
-/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
-/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
-/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
-/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
-/*************************************************************************/
-
-#include "core/multiplayer/multiplayer_replicator.h"
-
-#include "core/io/marshalls.h"
-#include "scene/main/node.h"
-#include "scene/resources/packed_scene.h"
-
-#define MAKE_ROOM(m_amount)             \
-	if (packet_cache.size() < m_amount) \
-		packet_cache.resize(m_amount);
-
-Error MultiplayerReplicator::_sync_all_default(const ResourceUID::ID &p_scene_id, int p_peer) {
-	ERR_FAIL_COND_V(!replications.has(p_scene_id), ERR_INVALID_PARAMETER);
-	SceneConfig &cfg = replications[p_scene_id];
-	int full_size = 0;
-	bool same_size = true;
-	int last_size = 0;
-	bool all_raw = true;
-	struct EncodeInfo {
-		int size = 0;
-		bool raw = false;
-		List<Variant> state;
-	};
-	Map<ObjectID, struct EncodeInfo> state;
-	if (tracked_objects.has(p_scene_id)) {
-		for (const ObjectID &obj_id : tracked_objects[p_scene_id]) {
-			Object *obj = ObjectDB::get_instance(obj_id);
-			if (obj) {
-				struct EncodeInfo info;
-				Error err = _get_state(cfg.sync_properties, obj, info.state);
-				ERR_CONTINUE(err);
-				err = _encode_state(info.state, nullptr, info.size, &info.raw);
-				ERR_CONTINUE(err);
-				state[obj_id] = info;
-				full_size += info.size;
-				if (last_size && info.size != last_size) {
-					same_size = false;
-				}
-				all_raw = all_raw && info.raw;
-				last_size = info.size;
-			}
-		}
-	}
-	// Default implementation do not send empty updates.
-	if (!full_size) {
-		return OK;
-	}
-#ifdef DEBUG_ENABLED
-	if (full_size > 4096 && cfg.sync_interval) {
-		WARN_PRINT_ONCE(vformat("The timed state update for scene %d is big (%d bytes) consider optimizing it", p_scene_id));
-	}
-#endif
-	if (same_size) {
-		// This is fast and small. Should we allow more than 256 objects per type?
-		// This costs us 1 byte.
-		MAKE_ROOM(SYNC_CMD_OFFSET + 1 + 2 + 2 + full_size);
-	} else {
-		MAKE_ROOM(SYNC_CMD_OFFSET + 1 + 2 + state.size() * 2 + full_size);
-	}
-	int ofs = 0;
-	uint8_t *ptr = packet_cache.ptrw();
-	ptr[0] = MultiplayerAPI::NETWORK_COMMAND_SYNC | (same_size ? BYTE_OR_ZERO_FLAG : 0);
-	ofs = 1;
-	ofs += encode_uint64(p_scene_id, &ptr[ofs]);
-	ptr[ofs] = cfg.sync_recv++;
-	ofs += 1;
-	ofs += encode_uint16(state.size(), &ptr[ofs]);
-	if (same_size) {
-		ofs += encode_uint16(last_size + (all_raw ? 1 << 15 : 0), &ptr[ofs]);
-	}
-	for (const ObjectID &obj_id : tracked_objects[p_scene_id]) {
-		if (!state.has(obj_id)) {
-			continue;
-		}
-		struct EncodeInfo &info = state[obj_id];
-		Object *obj = ObjectDB::get_instance(obj_id);
-		ERR_CONTINUE(!obj);
-		int size = 0;
-		if (!same_size) {
-			// We need to encode the size of every object.
-			ofs += encode_uint16(info.size + (info.raw ? 1 << 15 : 0), &ptr[ofs]);
-		}
-		Error err = _encode_state(info.state, &ptr[ofs], size, &info.raw);
-		ERR_CONTINUE(err);
-		ofs += size;
-	}
-	Ref<MultiplayerPeer> peer = multiplayer->get_multiplayer_peer();
-	peer->set_target_peer(p_peer);
-	peer->set_transfer_channel(0);
-	peer->set_transfer_mode(Multiplayer::TRANSFER_MODE_UNRELIABLE);
-	return peer->put_packet(ptr, ofs);
-}
-
-void MultiplayerReplicator::_process_default_sync(const ResourceUID::ID &p_id, const uint8_t *p_packet, int p_packet_len) {
-	ERR_FAIL_COND_MSG(p_packet_len < SYNC_CMD_OFFSET + 5, "Invalid spawn packet received");
-	ERR_FAIL_COND_MSG(!replications.has(p_id), "Invalid spawn ID received " + itos(p_id));
-	SceneConfig &cfg = replications[p_id];
-	ERR_FAIL_COND_MSG(cfg.mode != REPLICATION_MODE_SERVER || multiplayer->is_server(), "The default implementation only allows sync packets from the server");
-	const bool same_size = p_packet[0] & BYTE_OR_ZERO_FLAG;
-	int ofs = SYNC_CMD_OFFSET;
-	int time = p_packet[ofs];
-	// Skip old update.
-	if (time < cfg.sync_recv && cfg.sync_recv - time < 127) {
-		return;
-	}
-	cfg.sync_recv = time;
-	ofs += 1;
-	int count = decode_uint16(&p_packet[ofs]);
-	ofs += 2;
-#ifdef DEBUG_ENABLED
-	ERR_FAIL_COND(!tracked_objects.has(p_id) || tracked_objects[p_id].size() != count);
-#else
-	if (!tracked_objects.has(p_id) || tracked_objects[p_id].size() != count) {
-		return;
-	}
-#endif
-	int data_size = 0;
-	bool raw = false;
-	if (same_size) {
-		// This is fast and optimized.
-		data_size = decode_uint16(&p_packet[ofs]);
-		raw = (data_size & (1 << 15)) != 0;
-		data_size = data_size & ~(1 << 15);
-		ofs += 2;
-		ERR_FAIL_COND(p_packet_len - ofs < data_size * count);
-	}
-	for (const ObjectID &obj_id : tracked_objects[p_id]) {
-		Object *obj = ObjectDB::get_instance(obj_id);
-		ERR_CONTINUE(!obj);
-		if (!same_size) {
-			// This is slow and wasteful.
-			data_size = decode_uint16(&p_packet[ofs]);
-			raw = (data_size & (1 << 15)) != 0;
-			data_size = data_size & ~(1 << 15);
-			ofs += 2;
-			ERR_FAIL_COND(p_packet_len - ofs < data_size);
-		}
-		int size = 0;
-		Error err = _decode_state(cfg.sync_properties, obj, &p_packet[ofs], data_size, size, raw);
-		ofs += data_size;
-		ERR_CONTINUE(err);
-		ERR_CONTINUE(size != data_size);
-	}
-}
-
-Error MultiplayerReplicator::_send_default_spawn_despawn(int p_peer_id, const ResourceUID::ID &p_scene_id, Object *p_obj, const NodePath &p_path, bool p_spawn) {
-	ERR_FAIL_COND_V(p_spawn && !p_obj, ERR_INVALID_PARAMETER);
-	ERR_FAIL_COND_V(!replications.has(p_scene_id), ERR_INVALID_PARAMETER);
-	Error err;
-	// Prepare state
-	List<Variant> state_variants;
-	int state_len = 0;
-	const SceneConfig &cfg = replications[p_scene_id];
-	if (p_spawn) {
-		if ((err = _get_state(cfg.properties, p_obj, state_variants)) != OK) {
-			return err;
-		}
-	}
-
-	bool is_raw = false;
-	if (state_variants.size() == 1 && state_variants[0].get_type() == Variant::PACKED_BYTE_ARRAY) {
-		is_raw = true;
-		const PackedByteArray pba = state_variants[0];
-		state_len = pba.size();
-	} else if (state_variants.size()) {
-		err = _encode_state(state_variants, nullptr, state_len);
-		ERR_FAIL_COND_V(err, err);
-	} else {
-		is_raw = true;
-	}
-
-	int ofs = 0;
-
-	// Prepare simplified path
-	const Node *root_node = multiplayer->get_root_node();
-	ERR_FAIL_COND_V(!root_node, ERR_UNCONFIGURED);
-	NodePath rel_path = (root_node->get_path()).rel_path_to(p_path);
-	const Vector<StringName> names = rel_path.get_names();
-	ERR_FAIL_COND_V(names.size() < 2, ERR_INVALID_PARAMETER);
-
-	NodePath parent = NodePath(names.slice(0, names.size() - 1), false);
-	ERR_FAIL_COND_V_MSG(!root_node->has_node(parent), ERR_INVALID_PARAMETER, "Path not found: " + parent);
-
-	int path_id = 0;
-	multiplayer->send_confirm_path(root_node->get_node(parent), parent, p_peer_id, path_id);
-
-	// Encode name and parent ID.
-	CharString cname = String(names[names.size() - 1]).utf8();
-	int nlen = encode_cstring(cname.get_data(), nullptr);
-	MAKE_ROOM(SPAWN_CMD_OFFSET + 4 + 4 + nlen + state_len);
-	uint8_t *ptr = packet_cache.ptrw();
-	ptr[0] = (p_spawn ? MultiplayerAPI::NETWORK_COMMAND_SPAWN : MultiplayerAPI::NETWORK_COMMAND_DESPAWN) | (is_raw ? BYTE_OR_ZERO_FLAG : 0);
-	ofs = 1;
-	ofs += encode_uint64(p_scene_id, &ptr[ofs]);
-	ofs += encode_uint32(path_id, &ptr[ofs]);
-	ofs += encode_uint32(nlen, &ptr[ofs]);
-	ofs += encode_cstring(cname.get_data(), &ptr[ofs]);
-
-	// Encode state.
-	if (!is_raw) {
-		_encode_state(state_variants, &ptr[ofs], state_len);
-	} else if (state_len) {
-		PackedByteArray pba = state_variants[0];
-		memcpy(&ptr[ofs], pba.ptr(), state_len);
-	}
-
-	Ref<MultiplayerPeer> peer = multiplayer->get_multiplayer_peer();
-	peer->set_target_peer(p_peer_id);
-	peer->set_transfer_channel(0);
-	peer->set_transfer_mode(Multiplayer::TRANSFER_MODE_RELIABLE);
-	return peer->put_packet(ptr, ofs + state_len);
-}
-
-void MultiplayerReplicator::_process_default_spawn_despawn(int p_from, const ResourceUID::ID &p_scene_id, const uint8_t *p_packet, int p_packet_len, bool p_spawn) {
-	ERR_FAIL_COND_MSG(p_packet_len < SPAWN_CMD_OFFSET + 9, "Invalid spawn packet received");
-	int ofs = SPAWN_CMD_OFFSET;
-	uint32_t node_target = decode_uint32(&p_packet[ofs]);
-	Node *parent = multiplayer->get_cached_node(p_from, node_target);
-	ofs += 4;
-	ERR_FAIL_COND_MSG(parent == nullptr, "Invalid packet received. Requested node was not found.");
-
-	uint32_t name_len = decode_uint32(&p_packet[ofs]);
-	ofs += 4;
-	ERR_FAIL_COND_MSG(name_len > uint32_t(p_packet_len - ofs), vformat("Invalid spawn packet size: %d, wants: %d", p_packet_len, ofs + name_len));
-	ERR_FAIL_COND_MSG(name_len < 1, "Zero spawn name size.");
-
-	const String name = String::utf8((const char *)&p_packet[ofs], name_len);
-	// We need to make sure no trickery happens here (e.g. despawning a subpath), but we want to allow autogenerated ("@") node names.
-	ERR_FAIL_COND_MSG(name.validate_node_name() != name.replace("@", ""), vformat("Invalid node name received: '%s'", name));
-	ofs += name_len;
-
-	const SceneConfig &cfg = replications[p_scene_id];
-	if (cfg.mode == REPLICATION_MODE_SERVER && p_from == 1) {
-		String scene_path = ResourceUID::get_singleton()->get_id_path(p_scene_id);
-		if (p_spawn) {
-			const bool is_raw = ((p_packet[0] & BYTE_OR_ZERO_FLAG) >> BYTE_OR_ZERO_SHIFT) == 1;
-
-			ERR_FAIL_COND_MSG(parent->has_node(name), vformat("Unable to spawn node. Node already exists: %s/%s", parent->get_path(), name));
-			RES res = ResourceLoader::load(scene_path);
-			ERR_FAIL_COND_MSG(!res.is_valid(), "Unable to load scene to spawn at path: " + scene_path);
-			PackedScene *scene = Object::cast_to<PackedScene>(res.ptr());
-			ERR_FAIL_COND(!scene);
-			Node *node = scene->instantiate();
-			ERR_FAIL_COND(!node);
-			replicated_nodes[node->get_instance_id()] = p_scene_id;
-			_track(p_scene_id, node);
-			int size;
-			_decode_state(cfg.properties, node, &p_packet[ofs], p_packet_len - ofs, size, is_raw);
-			parent->_add_child_nocheck(node, name);
-			emit_signal(SNAME("spawned"), p_scene_id, node);
-		} else {
-			ERR_FAIL_COND_MSG(!parent->has_node(name), vformat("Path not found: %s/%s", parent->get_path(), name));
-			Node *node = parent->get_node(name);
-			ERR_FAIL_COND_MSG(!replicated_nodes.has(node->get_instance_id()), vformat("Trying to despawn a Node that was not replicated: %s/%s", parent->get_path(), name));
-			emit_signal(SNAME("despawned"), p_scene_id, node);
-			_untrack(p_scene_id, node);
-			replicated_nodes.erase(node->get_instance_id());
-			node->queue_delete();
-		}
-	} else {
-		PackedByteArray data;
-		if (p_packet_len > ofs) {
-			data.resize(p_packet_len - ofs);
-			memcpy(data.ptrw(), &p_packet[ofs], data.size());
-		}
-		if (p_spawn) {
-			emit_signal(SNAME("spawn_requested"), p_from, p_scene_id, parent, name, data);
-		} else {
-			emit_signal(SNAME("despawn_requested"), p_from, p_scene_id, parent, name, data);
-		}
-	}
-}
-
-void MultiplayerReplicator::process_spawn_despawn(int p_from, const uint8_t *p_packet, int p_packet_len, bool p_spawn) {
-	ERR_FAIL_COND_MSG(p_packet_len < SPAWN_CMD_OFFSET, "Invalid spawn packet received");
-	ResourceUID::ID id = decode_uint64(&p_packet[1]);
-	ERR_FAIL_COND_MSG(!replications.has(id), "Invalid spawn ID received " + itos(id));
-
-	const SceneConfig &cfg = replications[id];
-	if (cfg.on_spawn_despawn_receive.is_valid()) {
-		int ofs = SPAWN_CMD_OFFSET;
-		bool is_raw = ((p_packet[0] & BYTE_OR_ZERO_FLAG) >> BYTE_OR_ZERO_SHIFT) == 1;
-		Variant data;
-		int left = p_packet_len - ofs;
-		if (is_raw && left) {
-			PackedByteArray pba;
-			pba.resize(left);
-			memcpy(pba.ptrw(), &p_packet[ofs], pba.size());
-			data = pba;
-		} else if (left) {
-			ERR_FAIL_COND(decode_variant(data, &p_packet[ofs], left) != OK);
-		}
-
-		Variant args[4];
-		args[0] = p_from;
-		args[1] = id;
-		args[2] = data;
-		args[3] = p_spawn;
-		const Variant *argp[] = { &args[0], &args[1], &args[2], &args[3] };
-		Callable::CallError ce;
-		Variant ret;
-		cfg.on_spawn_despawn_receive.call(argp, 4, ret, ce);
-		ERR_FAIL_COND_MSG(ce.error != Callable::CallError::CALL_OK, "Custom receive function failed");
-	} else {
-		_process_default_spawn_despawn(p_from, id, p_packet, p_packet_len, p_spawn);
-	}
-}
-
-void MultiplayerReplicator::process_sync(int p_from, const uint8_t *p_packet, int p_packet_len) {
-	ERR_FAIL_COND_MSG(p_packet_len < SPAWN_CMD_OFFSET, "Invalid spawn packet received");
-	ResourceUID::ID id = decode_uint64(&p_packet[1]);
-	ERR_FAIL_COND_MSG(!replications.has(id), "Invalid spawn ID received " + itos(id));
-	const SceneConfig &cfg = replications[id];
-	if (cfg.on_sync_receive.is_valid()) {
-		Array objs;
-		if (tracked_objects.has(id)) {
-			objs.resize(tracked_objects[id].size());
-			int idx = 0;
-			for (const ObjectID &obj_id : tracked_objects[id]) {
-				objs[idx++] = ObjectDB::get_instance(obj_id);
-			}
-		}
-		PackedByteArray pba;
-		pba.resize(p_packet_len - SYNC_CMD_OFFSET);
-		if (pba.size()) {
-			memcpy(pba.ptrw(), p_packet + SYNC_CMD_OFFSET, p_packet_len - SYNC_CMD_OFFSET);
-		}
-		Variant args[4] = { p_from, id, objs, pba };
-		Variant *argp[4] = { args, &args[1], &args[2], &args[3] };
-		Callable::CallError ce;
-		Variant ret;
-		cfg.on_sync_receive.call((const Variant **)argp, 4, ret, ce);
-		ERR_FAIL_COND_MSG(ce.error != Callable::CallError::CALL_OK, "Custom sync function failed");
-	} else {
-		ERR_FAIL_COND_MSG(p_from != 1, "Default sync implementation only allow syncing from server to client");
-		_process_default_sync(id, p_packet, p_packet_len);
-	}
-}
-
-Error MultiplayerReplicator::_get_state(const List<StringName> &p_properties, const Object *p_obj, List<Variant> &r_variant) {
-	ERR_FAIL_COND_V_MSG(!p_obj, ERR_INVALID_PARAMETER, "Cannot encode null object");
-	for (const StringName &prop : p_properties) {
-		bool valid = false;
-		const Variant v = p_obj->get(prop, &valid);
-		ERR_FAIL_COND_V_MSG(!valid, ERR_INVALID_DATA, vformat("Property '%s' not found.", prop));
-		r_variant.push_back(v);
-	}
-	return OK;
-}
-
-Error MultiplayerReplicator::_encode_state(const List<Variant> &p_variants, uint8_t *p_buffer, int &r_len, bool *r_raw) {
-	r_len = 0;
-	int size = 0;
-
-	// Try raw encoding optimization.
-	if (r_raw && p_variants.size() == 1) {
-		*r_raw = false;
-		const Variant v = p_variants[0];
-		if (v.get_type() == Variant::PACKED_BYTE_ARRAY) {
-			*r_raw = true;
-			const PackedByteArray pba = v;
-			if (p_buffer) {
-				memcpy(p_buffer, pba.ptr(), pba.size());
-			}
-			r_len += pba.size();
-		} else {
-			multiplayer->encode_and_compress_variant(v, p_buffer, size);
-			r_len += size;
-		}
-		return OK;
-	}
-
-	// Regular encoding.
-	for (const Variant &v : p_variants) {
-		multiplayer->encode_and_compress_variant(v, p_buffer ? p_buffer + r_len : nullptr, size);
-		r_len += size;
-	}
-	return OK;
-}
-
-Error MultiplayerReplicator::_decode_state(const List<StringName> &p_properties, Object *p_obj, const uint8_t *p_buffer, int p_len, int &r_len, bool p_raw) {
-	r_len = 0;
-	int argc = p_properties.size();
-	if (argc == 0 && p_raw) {
-		ERR_FAIL_COND_V_MSG(p_len != 0, ERR_INVALID_DATA, "Buffer has trailing bytes.");
-		return OK;
-	}
-	ERR_FAIL_COND_V(p_raw && argc != 1, ERR_INVALID_DATA);
-	if (p_raw) {
-		r_len = p_len;
-		PackedByteArray pba;
-		pba.resize(p_len);
-		memcpy(pba.ptrw(), p_buffer, p_len);
-		p_obj->set(p_properties[0], pba);
-		return OK;
-	}
-
-	Vector<Variant> args;
-	Vector<const Variant *> argp;
-	args.resize(argc);
-
-	for (int i = 0; i < argc; i++) {
-		ERR_FAIL_COND_V_MSG(r_len >= p_len, ERR_INVALID_DATA, "Invalid packet received. Size too small.");
-
-		int vlen;
-		Error err = multiplayer->decode_and_decompress_variant(args.write[i], &p_buffer[r_len], p_len - r_len, &vlen);
-		ERR_FAIL_COND_V_MSG(err != OK, err, "Invalid packet received. Unable to decode state variable.");
-		r_len += vlen;
-	}
-	ERR_FAIL_COND_V_MSG(p_len - r_len != 0, ERR_INVALID_DATA, "Buffer has trailing bytes.");
-
-	int i = 0;
-	for (const StringName &prop : p_properties) {
-		p_obj->set(prop, args[i]);
-		i += 1;
-	}
-	return OK;
-}
-
-Error MultiplayerReplicator::spawn_config(const ResourceUID::ID &p_id, ReplicationMode p_mode, const TypedArray<StringName> &p_props, const Callable &p_on_send, const Callable &p_on_recv) {
-	ERR_FAIL_COND_V(p_mode < REPLICATION_MODE_NONE || p_mode > REPLICATION_MODE_CUSTOM, ERR_INVALID_PARAMETER);
-	ERR_FAIL_COND_V(!ResourceUID::get_singleton()->has_id(p_id), ERR_INVALID_PARAMETER);
-	ERR_FAIL_COND_V_MSG(p_on_send.is_valid() != p_on_recv.is_valid(), ERR_INVALID_PARAMETER, "Send and receive custom callables must be both valid or both empty");
-#ifdef TOOLS_ENABLED
-	if (!p_on_send.is_valid()) {
-		// We allow non scene spawning with custom callables.
-		String path = ResourceUID::get_singleton()->get_id_path(p_id);
-		RES res = ResourceLoader::load(path);
-		ERR_FAIL_COND_V(!res->is_class("PackedScene"), ERR_INVALID_PARAMETER);
-	}
-#endif
-	if (p_mode == REPLICATION_MODE_NONE) {
-		if (replications.has(p_id)) {
-			replications.erase(p_id);
-		}
-	} else {
-		SceneConfig cfg;
-		cfg.mode = p_mode;
-		for (int i = 0; i < p_props.size(); i++) {
-			cfg.properties.push_back(p_props[i]);
-		}
-		cfg.on_spawn_despawn_send = p_on_send;
-		cfg.on_spawn_despawn_receive = p_on_recv;
-		replications[p_id] = cfg;
-	}
-	return OK;
-}
-
-Error MultiplayerReplicator::sync_config(const ResourceUID::ID &p_id, uint64_t p_interval, const TypedArray<StringName> &p_props, const Callable &p_on_send, const Callable &p_on_recv) {
-	ERR_FAIL_COND_V(!ResourceUID::get_singleton()->has_id(p_id), ERR_INVALID_PARAMETER);
-	ERR_FAIL_COND_V_MSG(p_on_send.is_valid() != p_on_recv.is_valid(), ERR_INVALID_PARAMETER, "Send and receive custom callables must be both valid or both empty");
-	ERR_FAIL_COND_V(!replications.has(p_id), ERR_UNCONFIGURED);
-	SceneConfig &cfg = replications[p_id];
-	ERR_FAIL_COND_V_MSG(p_interval && cfg.mode != REPLICATION_MODE_SERVER && !p_on_send.is_valid(), ERR_INVALID_PARAMETER, "Timed updates in custom mode are only allowed if custom callbacks are also specified");
-	for (int i = 0; i < p_props.size(); i++) {
-		cfg.sync_properties.push_back(p_props[i]);
-	}
-	cfg.on_sync_send = p_on_send;
-	cfg.on_sync_receive = p_on_recv;
-	cfg.sync_interval = p_interval * 1000;
-	return OK;
-}
-
-Error MultiplayerReplicator::_send_spawn_despawn(int p_peer_id, const ResourceUID::ID &p_scene_id, const Variant &p_data, bool p_spawn) {
-	int data_size = 0;
-	int is_raw = false;
-	if (p_data.get_type() == Variant::PACKED_BYTE_ARRAY) {
-		const PackedByteArray pba = p_data;
-		is_raw = true;
-		data_size = p_data.operator PackedByteArray().size();
-	} else if (p_data.get_type() == Variant::NIL) {
-		is_raw = true;
-	} else {
-		Error err = encode_variant(p_data, nullptr, data_size);
-		ERR_FAIL_COND_V(err, err);
-	}
-	MAKE_ROOM(SPAWN_CMD_OFFSET + data_size);
-	uint8_t *ptr = packet_cache.ptrw();
-	ptr[0] = (p_spawn ? MultiplayerAPI::NETWORK_COMMAND_SPAWN : MultiplayerAPI::NETWORK_COMMAND_DESPAWN) + ((is_raw ? 1 : 0) << BYTE_OR_ZERO_SHIFT);
-	encode_uint64(p_scene_id, &ptr[1]);
-	if (p_data.get_type() == Variant::PACKED_BYTE_ARRAY) {
-		const PackedByteArray pba = p_data;
-		memcpy(&ptr[SPAWN_CMD_OFFSET], pba.ptr(), pba.size());
-	} else if (data_size) {
-		encode_variant(p_data, &ptr[SPAWN_CMD_OFFSET], data_size);
-	}
-	Ref<MultiplayerPeer> peer = multiplayer->get_multiplayer_peer();
-	peer->set_target_peer(p_peer_id);
-	peer->set_transfer_channel(0);
-	peer->set_transfer_mode(Multiplayer::TRANSFER_MODE_RELIABLE);
-	return peer->put_packet(ptr, SPAWN_CMD_OFFSET + data_size);
-}
-
-Error MultiplayerReplicator::send_despawn(int p_peer_id, const ResourceUID::ID &p_scene_id, const Variant &p_data, const NodePath &p_path) {
-	ERR_FAIL_COND_V(!multiplayer->has_multiplayer_peer(), ERR_UNCONFIGURED);
-	ERR_FAIL_COND_V_MSG(!replications.has(p_scene_id), ERR_INVALID_PARAMETER, vformat("Spawnable not found: %d", p_scene_id));
-	const SceneConfig &cfg = replications[p_scene_id];
-	if (cfg.on_spawn_despawn_send.is_valid()) {
-		return _send_spawn_despawn(p_peer_id, p_scene_id, p_data, true);
-	} else {
-		ERR_FAIL_COND_V_MSG(cfg.mode == REPLICATION_MODE_SERVER && multiplayer->is_server(), ERR_UNAVAILABLE, "Manual despawn is restricted in default server mode implementation. Use custom mode if you desire control over server spawn requests.");
-		NodePath path = p_path;
-		Object *obj = p_data.get_type() == Variant::OBJECT ? p_data.get_validated_object() : nullptr;
-		if (path.is_empty() && obj) {
-			Node *node = Object::cast_to<Node>(obj);
-			if (node && node->is_inside_tree()) {
-				path = node->get_path();
-			}
-		}
-		ERR_FAIL_COND_V_MSG(path.is_empty(), ERR_INVALID_PARAMETER, "Despawn default implementation requires a despawn path, or the data to be a node inside the SceneTree");
-		return _send_default_spawn_despawn(p_peer_id, p_scene_id, obj, path, false);
-	}
-}
-
-Error MultiplayerReplicator::send_spawn(int p_peer_id, const ResourceUID::ID &p_scene_id, const Variant &p_data, const NodePath &p_path) {
-	ERR_FAIL_COND_V(!multiplayer->has_multiplayer_peer(), ERR_UNCONFIGURED);
-	ERR_FAIL_COND_V_MSG(!replications.has(p_scene_id), ERR_INVALID_PARAMETER, vformat("Spawnable not found: %d", p_scene_id));
-	const SceneConfig &cfg = replications[p_scene_id];
-	if (cfg.on_spawn_despawn_send.is_valid()) {
-		return _send_spawn_despawn(p_peer_id, p_scene_id, p_data, false);
-	} else {
-		ERR_FAIL_COND_V_MSG(cfg.mode == REPLICATION_MODE_SERVER && multiplayer->is_server(), ERR_UNAVAILABLE, "Manual spawn is restricted in default server mode implementation. Use custom mode if you desire control over server spawn requests.");
-		NodePath path = p_path;
-		Object *obj = p_data.get_type() == Variant::OBJECT ? p_data.get_validated_object() : nullptr;
-		ERR_FAIL_COND_V_MSG(!obj, ERR_INVALID_PARAMETER, "Spawn default implementation requires the data to be an object.");
-		if (path.is_empty()) {
-			Node *node = Object::cast_to<Node>(obj);
-			if (node && node->is_inside_tree()) {
-				path = node->get_path();
-			}
-		}
-		ERR_FAIL_COND_V_MSG(path.is_empty(), ERR_INVALID_PARAMETER, "Spawn default implementation requires a spawn path, or the data to be a node inside the SceneTree");
-		return _send_default_spawn_despawn(p_peer_id, p_scene_id, obj, path, true);
-	}
-}
-
-Error MultiplayerReplicator::_spawn_despawn(ResourceUID::ID p_scene_id, Object *p_obj, int p_peer, bool p_spawn) {
-	ERR_FAIL_COND_V_MSG(!replications.has(p_scene_id), ERR_INVALID_PARAMETER, vformat("Spawnable not found: %d", p_scene_id));
-
-	const SceneConfig &cfg = replications[p_scene_id];
-	if (cfg.on_spawn_despawn_send.is_valid()) {
-		Variant args[4];
-		args[0] = p_peer;
-		args[1] = p_scene_id;
-		args[2] = p_obj;
-		args[3] = p_spawn;
-		const Variant *argp[] = { &args[0], &args[1], &args[2], &args[3] };
-		Callable::CallError ce;
-		Variant ret;
-		cfg.on_spawn_despawn_send.call(argp, 4, ret, ce);
-		ERR_FAIL_COND_V_MSG(ce.error != Callable::CallError::CALL_OK, FAILED, "Custom send function failed");
-		return OK;
-	} else {
-		Node *node = Object::cast_to<Node>(p_obj);
-		ERR_FAIL_COND_V_MSG(!p_obj, ERR_INVALID_PARAMETER, "Only nodes can be replicated by the default implementation");
-		return _send_default_spawn_despawn(p_peer, p_scene_id, node, node->get_path(), p_spawn);
-	}
-}
-
-Error MultiplayerReplicator::spawn(ResourceUID::ID p_scene_id, Object *p_obj, int p_peer) {
-	return _spawn_despawn(p_scene_id, p_obj, p_peer, true);
-}
-
-Error MultiplayerReplicator::despawn(ResourceUID::ID p_scene_id, Object *p_obj, int p_peer) {
-	return _spawn_despawn(p_scene_id, p_obj, p_peer, false);
-}
-
-PackedByteArray MultiplayerReplicator::encode_state(const ResourceUID::ID &p_scene_id, const Object *p_obj, bool p_initial) {
-	PackedByteArray state;
-	ERR_FAIL_COND_V_MSG(!replications.has(p_scene_id), state, vformat("Spawnable not found: %d", p_scene_id));
-	const SceneConfig &cfg = replications[p_scene_id];
-	int len = 0;
-	List<Variant> state_vars;
-	const List<StringName> props = p_initial ? cfg.properties : cfg.sync_properties;
-	Error err = _get_state(props, p_obj, state_vars);
-	ERR_FAIL_COND_V_MSG(err != OK, state, "Unable to retrieve object state.");
-	err = _encode_state(state_vars, nullptr, len);
-	ERR_FAIL_COND_V_MSG(err != OK, state, "Unable to encode object state.");
-	state.resize(len);
-	_encode_state(state_vars, state.ptrw(), len);
-	return state;
-}
-
-Error MultiplayerReplicator::decode_state(const ResourceUID::ID &p_scene_id, Object *p_obj, const PackedByteArray p_data, bool p_initial) {
-	ERR_FAIL_COND_V_MSG(!replications.has(p_scene_id), ERR_INVALID_PARAMETER, vformat("Spawnable not found: %d", p_scene_id));
-	const SceneConfig &cfg = replications[p_scene_id];
-	const List<StringName> props = p_initial ? cfg.properties : cfg.sync_properties;
-	int size;
-	return _decode_state(props, p_obj, p_data.ptr(), p_data.size(), size);
-}
-
-void MultiplayerReplicator::scene_enter_exit_notify(const String &p_scene, Node *p_node, bool p_enter) {
-	if (!multiplayer->has_multiplayer_peer()) {
-		return;
-	}
-	Node *root_node = multiplayer->get_root_node();
-	ERR_FAIL_COND(!p_node || !p_node->get_parent() || !root_node);
-	NodePath path = (root_node->get_path()).rel_path_to(p_node->get_parent()->get_path());
-	if (path.is_empty()) {
-		return;
-	}
-	ResourceUID::ID id = ResourceLoader::get_resource_uid(p_scene);
-	if (!replications.has(id)) {
-		return;
-	}
-	const SceneConfig &cfg = replications[id];
-	if (p_enter) {
-		if (cfg.mode == REPLICATION_MODE_SERVER && multiplayer->is_server()) {
-			replicated_nodes[p_node->get_instance_id()] = id;
-			_track(id, p_node);
-			spawn(id, p_node, 0);
-		}
-		emit_signal(SNAME("replicated_instance_added"), id, p_node);
-	} else {
-		if (cfg.mode == REPLICATION_MODE_SERVER && multiplayer->is_server() && replicated_nodes.has(p_node->get_instance_id())) {
-			replicated_nodes.erase(p_node->get_instance_id());
-			_untrack(id, p_node);
-			despawn(id, p_node, 0);
-		}
-		emit_signal(SNAME("replicated_instance_removed"), id, p_node);
-	}
-}
-
-void MultiplayerReplicator::spawn_all(int p_peer) {
-	for (const KeyValue<ObjectID, ResourceUID::ID> &E : replicated_nodes) {
-		// Only server mode adds to replicated_nodes, no need to check it.
-		Object *obj = ObjectDB::get_instance(E.key);
-		ERR_CONTINUE(!obj);
-		Node *node = Object::cast_to<Node>(obj);
-		ERR_CONTINUE(!node);
-		spawn(E.value, node, p_peer);
-	}
-}
-
-void MultiplayerReplicator::poll() {
-	for (KeyValue<ResourceUID::ID, SceneConfig> &E : replications) {
-		if (!E.value.sync_interval) {
-			continue;
-		}
-		if (E.value.mode == REPLICATION_MODE_SERVER && !multiplayer->is_server()) {
-			continue;
-		}
-		uint64_t time = OS::get_singleton()->get_ticks_usec();
-		if (E.value.sync_last + E.value.sync_interval <= time) {
-			sync_all(E.key, 0);
-			E.value.sync_last = time;
-		}
-		// Handle wrapping.
-		if (E.value.sync_last > time) {
-			E.value.sync_last = time;
-		}
-	}
-}
-
-void MultiplayerReplicator::track(const ResourceUID::ID &p_scene_id, Object *p_obj) {
-	ERR_FAIL_COND(!replications.has(p_scene_id));
-	const SceneConfig &cfg = replications[p_scene_id];
-	ERR_FAIL_COND_MSG(cfg.mode == REPLICATION_MODE_SERVER, "Manual object tracking is not allowed in server mode.");
-	_track(p_scene_id, p_obj);
-}
-
-void MultiplayerReplicator::_track(const ResourceUID::ID &p_scene_id, Object *p_obj) {
-	ERR_FAIL_COND(!p_obj);
-	ERR_FAIL_COND(!replications.has(p_scene_id));
-	if (!tracked_objects.has(p_scene_id)) {
-		tracked_objects[p_scene_id] = List<ObjectID>();
-	}
-	tracked_objects[p_scene_id].push_back(p_obj->get_instance_id());
-}
-
-void MultiplayerReplicator::untrack(const ResourceUID::ID &p_scene_id, Object *p_obj) {
-	ERR_FAIL_COND(!replications.has(p_scene_id));
-	const SceneConfig &cfg = replications[p_scene_id];
-	ERR_FAIL_COND_MSG(cfg.mode == REPLICATION_MODE_SERVER, "Manual object tracking is not allowed in server mode.");
-	_untrack(p_scene_id, p_obj);
-}
-
-void MultiplayerReplicator::_untrack(const ResourceUID::ID &p_scene_id, Object *p_obj) {
-	ERR_FAIL_COND(!p_obj);
-	ERR_FAIL_COND(!replications.has(p_scene_id));
-	if (tracked_objects.has(p_scene_id)) {
-		tracked_objects[p_scene_id].erase(p_obj->get_instance_id());
-	}
-}
-
-Error MultiplayerReplicator::sync_all(const ResourceUID::ID &p_scene_id, int p_peer) {
-	ERR_FAIL_COND_V(!replications.has(p_scene_id), ERR_INVALID_PARAMETER);
-	if (!tracked_objects.has(p_scene_id)) {
-		return OK;
-	}
-	const SceneConfig &cfg = replications[p_scene_id];
-	if (cfg.on_sync_send.is_valid()) {
-		Array objs;
-		if (tracked_objects.has(p_scene_id)) {
-			objs.resize(tracked_objects[p_scene_id].size());
-			int idx = 0;
-			for (const ObjectID &obj_id : tracked_objects[p_scene_id]) {
-				objs[idx++] = ObjectDB::get_instance(obj_id);
-			}
-		}
-		Variant args[3] = { p_scene_id, objs, p_peer };
-		Variant *argp[3] = { args, &args[1], &args[2] };
-		Callable::CallError ce;
-		Variant ret;
-		cfg.on_sync_send.call((const Variant **)argp, 3, ret, ce);
-		ERR_FAIL_COND_V_MSG(ce.error != Callable::CallError::CALL_OK, FAILED, "Custom sync function failed");
-		return OK;
-	} else if (cfg.sync_properties.size()) {
-		return _sync_all_default(p_scene_id, p_peer);
-	}
-	return OK;
-}
-
-Error MultiplayerReplicator::send_sync(int p_peer_id, const ResourceUID::ID &p_scene_id, PackedByteArray p_data, Multiplayer::TransferMode p_transfer_mode, int p_channel) {
-	ERR_FAIL_COND_V(!multiplayer->has_multiplayer_peer(), ERR_UNCONFIGURED);
-	ERR_FAIL_COND_V(!replications.has(p_scene_id), ERR_INVALID_PARAMETER);
-	const SceneConfig &cfg = replications[p_scene_id];
-	ERR_FAIL_COND_V_MSG(!cfg.on_sync_send.is_valid(), ERR_UNCONFIGURED, "Sending raw sync messages is only available with custom functions");
-	MAKE_ROOM(SYNC_CMD_OFFSET + p_data.size());
-	uint8_t *ptr = packet_cache.ptrw();
-	ptr[0] = MultiplayerAPI::NETWORK_COMMAND_SYNC;
-	encode_uint64(p_scene_id, &ptr[1]);
-	if (p_data.size()) {
-		memcpy(&ptr[SYNC_CMD_OFFSET], p_data.ptr(), p_data.size());
-	}
-	Ref<MultiplayerPeer> peer = multiplayer->get_multiplayer_peer();
-	peer->set_target_peer(p_peer_id);
-	peer->set_transfer_channel(p_channel);
-	peer->set_transfer_mode(p_transfer_mode);
-	return peer->put_packet(ptr, SYNC_CMD_OFFSET + p_data.size());
-}
-
-void MultiplayerReplicator::clear() {
-	tracked_objects.clear();
-	replicated_nodes.clear();
-}
-
-void MultiplayerReplicator::_bind_methods() {
-	ClassDB::bind_method(D_METHOD("spawn_config", "scene_id", "spawn_mode", "properties", "custom_send", "custom_receive"), &MultiplayerReplicator::spawn_config, DEFVAL(TypedArray<StringName>()), DEFVAL(Callable()), DEFVAL(Callable()));
-	ClassDB::bind_method(D_METHOD("sync_config", "scene_id", "interval", "properties", "custom_send", "custom_receive"), &MultiplayerReplicator::sync_config, DEFVAL(TypedArray<StringName>()), DEFVAL(Callable()), DEFVAL(Callable()));
-	ClassDB::bind_method(D_METHOD("despawn", "scene_id", "object", "peer_id"), &MultiplayerReplicator::despawn, DEFVAL(0));
-	ClassDB::bind_method(D_METHOD("spawn", "scene_id", "object", "peer_id"), &MultiplayerReplicator::spawn, DEFVAL(0));
-	ClassDB::bind_method(D_METHOD("send_despawn", "peer_id", "scene_id", "data", "path"), &MultiplayerReplicator::send_despawn, DEFVAL(Variant()), DEFVAL(NodePath()));
-	ClassDB::bind_method(D_METHOD("send_spawn", "peer_id", "scene_id", "data", "path"), &MultiplayerReplicator::send_spawn, DEFVAL(Variant()), DEFVAL(NodePath()));
-	ClassDB::bind_method(D_METHOD("send_sync", "peer_id", "scene_id", "data", "transfer_mode", "channel"), &MultiplayerReplicator::send_sync, DEFVAL(Multiplayer::TRANSFER_MODE_RELIABLE), DEFVAL(0));
-	ClassDB::bind_method(D_METHOD("sync_all", "scene_id", "peer_id"), &MultiplayerReplicator::sync_all, DEFVAL(0));
-	ClassDB::bind_method(D_METHOD("track", "scene_id", "object"), &MultiplayerReplicator::track);
-	ClassDB::bind_method(D_METHOD("untrack", "scene_id", "object"), &MultiplayerReplicator::untrack);
-	ClassDB::bind_method(D_METHOD("encode_state", "scene_id", "object", "initial"), &MultiplayerReplicator::encode_state, DEFVAL(true));
-	ClassDB::bind_method(D_METHOD("decode_state", "scene_id", "object", "data", "initial"), &MultiplayerReplicator::decode_state, DEFVAL(true));
-
-	ADD_SIGNAL(MethodInfo("despawned", PropertyInfo(Variant::INT, "scene_id"), PropertyInfo(Variant::OBJECT, "node", PROPERTY_HINT_RESOURCE_TYPE, "Node")));
-	ADD_SIGNAL(MethodInfo("spawned", PropertyInfo(Variant::INT, "scene_id"), PropertyInfo(Variant::OBJECT, "node", PROPERTY_HINT_RESOURCE_TYPE, "Node")));
-	ADD_SIGNAL(MethodInfo("despawn_requested", PropertyInfo(Variant::INT, "id"), PropertyInfo(Variant::INT, "scene_id"), PropertyInfo(Variant::OBJECT, "parent", PROPERTY_HINT_RESOURCE_TYPE, "Node"), PropertyInfo(Variant::STRING, "name"), PropertyInfo(Variant::PACKED_BYTE_ARRAY, "data")));
-	ADD_SIGNAL(MethodInfo("spawn_requested", PropertyInfo(Variant::INT, "id"), PropertyInfo(Variant::INT, "scene_id"), PropertyInfo(Variant::OBJECT, "parent", PROPERTY_HINT_RESOURCE_TYPE, "Node"), PropertyInfo(Variant::STRING, "name"), PropertyInfo(Variant::PACKED_BYTE_ARRAY, "data")));
-	ADD_SIGNAL(MethodInfo("replicated_instance_added", PropertyInfo(Variant::INT, "scene_id"), PropertyInfo(Variant::OBJECT, "node", PROPERTY_HINT_RESOURCE_TYPE, "Node")));
-	ADD_SIGNAL(MethodInfo("replicated_instance_removed", PropertyInfo(Variant::INT, "scene_id"), PropertyInfo(Variant::OBJECT, "node", PROPERTY_HINT_RESOURCE_TYPE, "Node")));
-
-	BIND_ENUM_CONSTANT(REPLICATION_MODE_NONE);
-	BIND_ENUM_CONSTANT(REPLICATION_MODE_SERVER);
-	BIND_ENUM_CONSTANT(REPLICATION_MODE_CUSTOM);
-}
diff --git a/core/multiplayer/multiplayer_replicator.h b/core/multiplayer/multiplayer_replicator.h
deleted file mode 100644
index a9cd6e211e..0000000000
--- a/core/multiplayer/multiplayer_replicator.h
+++ /dev/null
@@ -1,138 +0,0 @@
-/*************************************************************************/
-/*  multiplayer_replicator.h                                             */
-/*************************************************************************/
-/*                       This file is part of:                           */
-/*                           GODOT ENGINE                                */
-/*                      https://godotengine.org                          */
-/*************************************************************************/
-/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
-/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
-/*                                                                       */
-/* Permission is hereby granted, free of charge, to any person obtaining */
-/* a copy of this software and associated documentation files (the       */
-/* "Software"), to deal in the Software without restriction, including   */
-/* without limitation the rights to use, copy, modify, merge, publish,   */
-/* distribute, sublicense, and/or sell copies of the Software, and to    */
-/* permit persons to whom the Software is furnished to do so, subject to */
-/* the following conditions:                                             */
-/*                                                                       */
-/* The above copyright notice and this permission notice shall be        */
-/* included in all copies or substantial portions of the Software.       */
-/*                                                                       */
-/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
-/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
-/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
-/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
-/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
-/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
-/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
-/*************************************************************************/
-
-#ifndef MULTIPLAYER_REPLICATOR_H
-#define MULTIPLAYER_REPLICATOR_H
-
-#include "core/multiplayer/multiplayer_api.h"
-
-#include "core/io/resource_uid.h"
-#include "core/templates/hash_map.h"
-#include "core/variant/typed_array.h"
-
-class MultiplayerReplicator : public Object {
-	GDCLASS(MultiplayerReplicator, Object);
-
-public:
-	enum {
-		SPAWN_CMD_OFFSET = 9,
-		SYNC_CMD_OFFSET = 9,
-	};
-
-	enum ReplicationMode {
-		REPLICATION_MODE_NONE,
-		REPLICATION_MODE_SERVER,
-		REPLICATION_MODE_CUSTOM,
-	};
-
-	struct SceneConfig {
-		ReplicationMode mode;
-		uint64_t sync_interval = 0;
-		uint64_t sync_last = 0;
-		uint8_t sync_recv = 0;
-		List<StringName> properties;
-		List<StringName> sync_properties;
-		Callable on_spawn_despawn_send;
-		Callable on_spawn_despawn_receive;
-		Callable on_sync_send;
-		Callable on_sync_receive;
-	};
-
-protected:
-	static void _bind_methods();
-
-private:
-	enum {
-		BYTE_OR_ZERO_SHIFT = MultiplayerAPI::CMD_FLAG_0_SHIFT,
-	};
-
-	enum {
-		BYTE_OR_ZERO_FLAG = 1 << BYTE_OR_ZERO_SHIFT,
-	};
-
-	MultiplayerAPI *multiplayer = nullptr;
-	Vector<uint8_t> packet_cache;
-	Map<ResourceUID::ID, SceneConfig> replications;
-	Map<ObjectID, ResourceUID::ID> replicated_nodes;
-	HashMap<ResourceUID::ID, List<ObjectID>> tracked_objects;
-
-	// Encoding
-	Error _get_state(const List<StringName> &p_properties, const Object *p_obj, List<Variant> &r_variant);
-	Error _encode_state(const List<Variant> &p_variants, uint8_t *p_buffer, int &r_len, bool *r_raw = nullptr);
-	Error _decode_state(const List<StringName> &p_cfg, Object *p_obj, const uint8_t *p_buffer, int p_len, int &r_len, bool p_raw = false);
-
-	// Spawn
-	Error _spawn_despawn(ResourceUID::ID p_scene_id, Object *p_obj, int p_peer, bool p_spawn);
-	Error _send_spawn_despawn(int p_peer_id, const ResourceUID::ID &p_scene_id, const Variant &p_data, bool p_spawn);
-	void _process_default_spawn_despawn(int p_from, const ResourceUID::ID &p_scene_id, const uint8_t *p_packet, int p_packet_len, bool p_spawn);
-	Error _send_default_spawn_despawn(int p_peer_id, const ResourceUID::ID &p_scene_id, Object *p_obj, const NodePath &p_path, bool p_spawn);
-
-	// Sync
-	void _process_default_sync(const ResourceUID::ID &p_id, const uint8_t *p_packet, int p_packet_len);
-	Error _sync_all_default(const ResourceUID::ID &p_scene_id, int p_peer);
-	void _track(const ResourceUID::ID &p_scene_id, Object *p_object);
-	void _untrack(const ResourceUID::ID &p_scene_id, Object *p_object);
-
-public:
-	void clear();
-
-	// Encoding
-	PackedByteArray encode_state(const ResourceUID::ID &p_scene_id, const Object *p_node, bool p_initial);
-	Error decode_state(const ResourceUID::ID &p_scene_id, Object *p_node, PackedByteArray p_data, bool p_initial);
-
-	// Spawn
-	Error spawn_config(const ResourceUID::ID &p_id, ReplicationMode p_mode, const TypedArray<StringName> &p_props = TypedArray<StringName>(), const Callable &p_on_send = Callable(), const Callable &p_on_recv = Callable());
-	Error spawn(ResourceUID::ID p_scene_id, Object *p_obj, int p_peer = 0);
-	Error despawn(ResourceUID::ID p_scene_id, Object *p_obj, int p_peer = 0);
-	Error send_despawn(int p_peer_id, const ResourceUID::ID &p_scene_id, const Variant &p_data = Variant(), const NodePath &p_path = NodePath());
-	Error send_spawn(int p_peer_id, const ResourceUID::ID &p_scene_id, const Variant &p_data = Variant(), const NodePath &p_path = NodePath());
-
-	// Sync
-	Error sync_config(const ResourceUID::ID &p_id, uint64_t p_interval, const TypedArray<StringName> &p_props = TypedArray<StringName>(), const Callable &p_on_send = Callable(), const Callable &p_on_recv = Callable());
-	Error sync_all(const ResourceUID::ID &p_scene_id, int p_peer);
-	Error send_sync(int p_peer_id, const ResourceUID::ID &p_scene_id, PackedByteArray p_data, Multiplayer::TransferMode p_mode, int p_channel);
-	void track(const ResourceUID::ID &p_scene_id, Object *p_object);
-	void untrack(const ResourceUID::ID &p_scene_id, Object *p_object);
-
-	// Used by MultiplayerAPI
-	void spawn_all(int p_peer);
-	void process_spawn_despawn(int p_from, const uint8_t *p_packet, int p_packet_len, bool p_spawn);
-	void process_sync(int p_from, const uint8_t *p_packet, int p_packet_len);
-	void scene_enter_exit_notify(const String &p_scene, Node *p_node, bool p_enter);
-	void poll();
-
-	MultiplayerReplicator(MultiplayerAPI *p_multiplayer) {
-		multiplayer = p_multiplayer;
-	}
-};
-
-VARIANT_ENUM_CAST(MultiplayerReplicator::ReplicationMode);
-
-#endif // MULTIPLAYER_REPLICATOR_H
diff --git a/core/multiplayer/rpc_manager.cpp b/core/multiplayer/rpc_manager.cpp
index 7736637349..1e6d2108be 100644
--- a/core/multiplayer/rpc_manager.cpp
+++ b/core/multiplayer/rpc_manager.cpp
@@ -235,16 +235,12 @@ void RPCManager::_process_rpc(Node *p_node, const uint16_t p_rpc_method_id, int
 	ERR_FAIL_COND_MSG(!can_call, "RPC '" + String(config.name) + "' is not allowed on node " + p_node->get_path() + " from: " + itos(p_from) + ". Mode is " + itos((int)config.rpc_mode) + ", authority is " + itos(p_node->get_multiplayer_authority()) + ".");
 
 	int argc = 0;
-	bool byte_only = false;
 
 	const bool byte_only_or_no_args = p_packet[0] & BYTE_ONLY_OR_NO_ARGS_FLAG;
 	if (byte_only_or_no_args) {
 		if (p_offset < p_packet_len) {
 			// This packet contains only bytes.
 			argc = 1;
-			byte_only = true;
-		} else {
-			// This rpc calls a method without parameters.
 		}
 	} else {
 		// Normal variant, takes the argument count from the packet.
@@ -262,25 +258,10 @@ void RPCManager::_process_rpc(Node *p_node, const uint16_t p_rpc_method_id, int
 	_profile_node_data("in_rpc", p_node->get_instance_id());
 #endif
 
-	if (byte_only) {
-		Vector<uint8_t> pure_data;
-		const int len = p_packet_len - p_offset;
-		pure_data.resize(len);
-		memcpy(pure_data.ptrw(), &p_packet[p_offset], len);
-		args.write[0] = pure_data;
-		argp.write[0] = &args[0];
-		p_offset += len;
-	} else {
-		for (int i = 0; i < argc; i++) {
-			ERR_FAIL_COND_MSG(p_offset >= p_packet_len, "Invalid packet received. Size too small.");
-
-			int vlen;
-			Error err = multiplayer->decode_and_decompress_variant(args.write[i], &p_packet[p_offset], p_packet_len - p_offset, &vlen);
-			ERR_FAIL_COND_MSG(err != OK, "Invalid packet received. Unable to decode RPC argument.");
-
-			argp.write[i] = &args[i];
-			p_offset += vlen;
-		}
+	int out;
+	MultiplayerAPI::decode_and_decompress_variants(args, &p_packet[p_offset], p_packet_len - p_offset, out, byte_only_or_no_args, multiplayer->is_object_decoding_allowed());
+	for (int i = 0; i < argc; i++) {
+		argp.write[i] = &args[i];
 	}
 
 	Callable::CallError ce;
@@ -380,28 +361,19 @@ void RPCManager::_send_rpc(Node *p_from, int p_to, uint16_t p_rpc_id, const Mult
 		ofs += 2;
 	}
 
-	if (p_argcount == 0) {
-		byte_only_or_no_args = true;
-	} else if (p_argcount == 1 && p_arg[0]->get_type() == Variant::PACKED_BYTE_ARRAY) {
-		byte_only_or_no_args = true;
-		// Special optimization when only the byte vector is sent.
-		const Vector<uint8_t> data = *p_arg[0];
-		MAKE_ROOM(ofs + data.size());
-		memcpy(&(packet_cache.write[ofs]), data.ptr(), sizeof(uint8_t) * data.size());
-		ofs += data.size();
+	int len;
+	Error err = MultiplayerAPI::encode_and_compress_variants(p_arg, p_argcount, nullptr, len, &byte_only_or_no_args, multiplayer->is_object_decoding_allowed());
+	ERR_FAIL_COND_MSG(err != OK, "Unable to encode RPC arguments. THIS IS LIKELY A BUG IN THE ENGINE!");
+	if (byte_only_or_no_args) {
+		MAKE_ROOM(ofs + len);
 	} else {
-		// Arguments
-		MAKE_ROOM(ofs + 1);
+		MAKE_ROOM(ofs + 1 + len);
 		packet_cache.write[ofs] = p_argcount;
 		ofs += 1;
-		for (int i = 0; i < p_argcount; i++) {
-			int len(0);
-			Error err = multiplayer->encode_and_compress_variant(*p_arg[i], nullptr, len);
-			ERR_FAIL_COND_MSG(err != OK, "Unable to encode RPC argument. THIS IS LIKELY A BUG IN THE ENGINE!");
-			MAKE_ROOM(ofs + len);
-			multiplayer->encode_and_compress_variant(*p_arg[i], &(packet_cache.write[ofs]), len);
-			ofs += len;
-		}
+	}
+	if (len) {
+		MultiplayerAPI::encode_and_compress_variants(p_arg, p_argcount, &packet_cache.write[ofs], len, &byte_only_or_no_args, multiplayer->is_object_decoding_allowed());
+		ofs += len;
 	}
 
 	ERR_FAIL_COND(command_type > 7);
diff --git a/core/register_core_types.cpp b/core/register_core_types.cpp
index a18ec4d6ad..388368d181 100644
--- a/core/register_core_types.cpp
+++ b/core/register_core_types.cpp
@@ -69,7 +69,6 @@
 #include "core/math/triangle_mesh.h"
 #include "core/multiplayer/multiplayer_api.h"
 #include "core/multiplayer/multiplayer_peer.h"
-#include "core/multiplayer/multiplayer_replicator.h"
 #include "core/object/class_db.h"
 #include "core/object/undo_redo.h"
 #include "core/os/main_loop.h"
@@ -200,7 +199,6 @@ void register_core_types() {
 
 	GDREGISTER_VIRTUAL_CLASS(MultiplayerPeer);
 	GDREGISTER_CLASS(MultiplayerPeerExtension);
-	GDREGISTER_VIRTUAL_CLASS(MultiplayerReplicator);
 	GDREGISTER_CLASS(MultiplayerAPI);
 	GDREGISTER_CLASS(MainLoop);
 	GDREGISTER_CLASS(Translation);
diff --git a/doc/classes/MultiplayerAPI.xml b/doc/classes/MultiplayerAPI.xml
index e0da08f5bd..426d902983 100644
--- a/doc/classes/MultiplayerAPI.xml
+++ b/doc/classes/MultiplayerAPI.xml
@@ -79,8 +79,6 @@
 		<member name="refuse_new_connections" type="bool" setter="set_refuse_new_connections" getter="is_refusing_new_connections" default="false">
 			If [code]true[/code], the MultiplayerAPI's [member multiplayer_peer] refuses new incoming connections.
 		</member>
-		<member name="replicator" type="MultiplayerReplicator" setter="" getter="get_replicator">
-		</member>
 		<member name="root_node" type="Node" setter="set_root_node" getter="get_root_node">
 			The root node to use for RPCs. Instead of an absolute path, a relative path will be used to find the node upon which the RPC should be executed.
 			This effectively allows to have different branches of the scene tree to be managed by different MultiplayerAPI, allowing for example to run both client and server in the same scene.
diff --git a/doc/classes/MultiplayerReplicator.xml b/doc/classes/MultiplayerReplicator.xml
deleted file mode 100644
index c2e93ddeab..0000000000
--- a/doc/classes/MultiplayerReplicator.xml
+++ /dev/null
@@ -1,191 +0,0 @@
-<?xml version="1.0" encoding="UTF-8" ?>
-<class name="MultiplayerReplicator" inherits="Object" version="4.0">
-	<brief_description>
-	</brief_description>
-	<description>
-	</description>
-	<tutorials>
-	</tutorials>
-	<methods>
-		<method name="decode_state">
-			<return type="int" enum="Error" />
-			<argument index="0" name="scene_id" type="int" />
-			<argument index="1" name="object" type="Object" />
-			<argument index="2" name="data" type="PackedByteArray" />
-			<argument index="3" name="initial" type="bool" default="true" />
-			<description>
-				Decode the given [code]data[/code] representing a spawnable state into [code]object[/code] using the configuration associated with the provided [code]scene_id[/code]. This function is called automatically when a client receives a server spawn for a scene with [constant REPLICATION_MODE_SERVER]. See [method spawn_config].
-				Tip: You may find this function useful in servers when parsing spawn requests from clients, or when implementing your own logic with [constant REPLICATION_MODE_CUSTOM].
-			</description>
-		</method>
-		<method name="despawn">
-			<return type="int" enum="Error" />
-			<argument index="0" name="scene_id" type="int" />
-			<argument index="1" name="object" type="Object" />
-			<argument index="2" name="peer_id" type="int" default="0" />
-			<description>
-				Request a despawn for the scene identified by [code]scene_id[/code] to the given [code]peer_id[/code]. This will either trigger the default behavior, or invoke the custom spawn/despawn callables specified in [method spawn_config]. See [method send_despawn] for the default behavior.
-			</description>
-		</method>
-		<method name="encode_state">
-			<return type="PackedByteArray" />
-			<argument index="0" name="scene_id" type="int" />
-			<argument index="1" name="object" type="Object" />
-			<argument index="2" name="initial" type="bool" default="true" />
-			<description>
-				Encode the given [code]object[/code] using the configuration associated with the provided [code]scene_id[/code]. This function is called automatically when the server spawns scenes with [constant REPLICATION_MODE_SERVER]. See [method spawn_config].
-				Tip: You may find this function useful when requesting spawns from clients to server, or when implementing your own logic with [constant REPLICATION_MODE_CUSTOM].
-			</description>
-		</method>
-		<method name="send_despawn">
-			<return type="int" enum="Error" />
-			<argument index="0" name="peer_id" type="int" />
-			<argument index="1" name="scene_id" type="int" />
-			<argument index="2" name="data" type="Variant" default="null" />
-			<argument index="3" name="path" type="NodePath" default="NodePath(&quot;&quot;)" />
-			<description>
-				Sends a despawn request for the scene identified by [code]scene_id[/code] to the given [code]peer_id[/code] (see [method MultiplayerPeer.set_target_peer]). If the scene is configured as [constant REPLICATION_MODE_SERVER] (see [method spawn_config]) and the request is sent by the server (see [method MultiplayerAPI.is_server]), the receiving peer(s) will automatically queue for deletion the node at [code]path[/code] and emit the signal [signal despawned]. In all other cases no deletion happens, and the signal [signal despawn_requested] is emitted instead.
-			</description>
-		</method>
-		<method name="send_spawn">
-			<return type="int" enum="Error" />
-			<argument index="0" name="peer_id" type="int" />
-			<argument index="1" name="scene_id" type="int" />
-			<argument index="2" name="data" type="Variant" default="null" />
-			<argument index="3" name="path" type="NodePath" default="NodePath(&quot;&quot;)" />
-			<description>
-				Sends a spawn request for the scene identified by [code]scene_id[/code] to the given [code]peer_id[/code] (see [method MultiplayerPeer.set_target_peer]). If the scene is configured as [constant REPLICATION_MODE_SERVER] (see [method spawn_config]) and the request is sent by the server (see [method MultiplayerAPI.is_server]), the receiving peer(s) will automatically instantiate that scene, add it to the [SceneTree] at the given [code]path[/code] and emit the signal [signal spawned]. In all other cases no instantiation happens, and the signal [signal spawn_requested] is emitted instead.
-			</description>
-		</method>
-		<method name="send_sync">
-			<return type="int" enum="Error" />
-			<argument index="0" name="peer_id" type="int" />
-			<argument index="1" name="scene_id" type="int" />
-			<argument index="2" name="data" type="PackedByteArray" />
-			<argument index="3" name="transfer_mode" type="int" enum="TransferMode" default="2" />
-			<argument index="4" name="channel" type="int" default="0" />
-			<description>
-				Sends a sync request for the instances of the scene identified by [code]scene_id[/code] to the given [code]peer_id[/code] (see [method MultiplayerPeer.set_target_peer]). This function can only be called manually when overriding the send and receive sync functions (see [method sync_config]).
-			</description>
-		</method>
-		<method name="spawn">
-			<return type="int" enum="Error" />
-			<argument index="0" name="scene_id" type="int" />
-			<argument index="1" name="object" type="Object" />
-			<argument index="2" name="peer_id" type="int" default="0" />
-			<description>
-				Request a spawn for the scene identified by [code]scene_id[/code] to the given [code]peer_id[/code]. This will either trigger the default behavior, or invoke the custom spawn/despawn callables specified in [method spawn_config]. See [method send_spawn] for the default behavior.
-			</description>
-		</method>
-		<method name="spawn_config">
-			<return type="int" enum="Error" />
-			<argument index="0" name="scene_id" type="int" />
-			<argument index="1" name="spawn_mode" type="int" enum="MultiplayerReplicator.ReplicationMode" />
-			<argument index="2" name="properties" type="StringName[]" default="[]" />
-			<argument index="3" name="custom_send" type="Callable" />
-			<argument index="4" name="custom_receive" type="Callable" />
-			<description>
-				Configures the MultiplayerReplicator to track instances of the [PackedScene] identified by [code]scene_id[/code] (see [method ResourceLoader.get_resource_uid]) for the purpose of network replication. When [code]mode[/code] is [constant REPLICATION_MODE_SERVER], the specified [code]properties[/code] will also be replicated to clients during the initial spawn. You can optionally specify a [code]custom_send[/code] and a [code]custom_receive[/code] to override the default behavior and customize the spawn/despawn proecess.
-				Tip: You can use a custom property in the scene main script to return a customly optimized state representation.
-			</description>
-		</method>
-		<method name="sync_all">
-			<return type="int" enum="Error" />
-			<argument index="0" name="scene_id" type="int" />
-			<argument index="1" name="peer_id" type="int" default="0" />
-			<description>
-				Manually request a sync for all the instances of the scene identified by [code]scene_id[/code]. This function will trigger the default sync behavior, or call your send custom send callable if specified in [method sync_config].
-				[b]Note:[/b] The default implementation only allow syncing from server to clients.
-			</description>
-		</method>
-		<method name="sync_config">
-			<return type="int" enum="Error" />
-			<argument index="0" name="scene_id" type="int" />
-			<argument index="1" name="interval" type="int" />
-			<argument index="2" name="properties" type="StringName[]" default="[]" />
-			<argument index="3" name="custom_send" type="Callable" />
-			<argument index="4" name="custom_receive" type="Callable" />
-			<description>
-				Configures the MultiplayerReplicator to sync instances of the [PackedScene] identified by [code]scene_id[/code] (see [method ResourceLoader.get_resource_uid]) for the purpose of network replication at the desired [code]interval[/code] (in milliseconds). The specified [code]properties[/code] will be part of the state sync. You can optionally specify a [code]custom_send[/code] and a [code]custom_receive[/code] to override the default behavior and customize the synchronization proecess.
-				Tip: You can use a custom property in the scene main script to return a customly optimized state representation (having a single property that returns a PackedByteArray is highly recommended when dealing with many instances).
-			</description>
-		</method>
-		<method name="track">
-			<return type="void" />
-			<argument index="0" name="scene_id" type="int" />
-			<argument index="1" name="object" type="Object" />
-			<description>
-				Track the given [code]object[/code] as an instance of the scene identified by [code]scene_id[/code]. This object will be passed to your custom sync callables (see [method sync_config]). Tracking and untracking is automatic in [constant REPLICATION_MODE_SERVER].
-			</description>
-		</method>
-		<method name="untrack">
-			<return type="void" />
-			<argument index="0" name="scene_id" type="int" />
-			<argument index="1" name="object" type="Object" />
-			<description>
-				Untrack the given [code]object[/code]. This object will no longer be passed to your custom sync callables (see [method sync_config]). Tracking and untracking is automatic in [constant REPLICATION_MODE_SERVER].
-			</description>
-		</method>
-	</methods>
-	<signals>
-		<signal name="despawn_requested">
-			<argument index="0" name="id" type="int" />
-			<argument index="1" name="scene_id" type="int" />
-			<argument index="2" name="parent" type="Node" />
-			<argument index="3" name="name" type="String" />
-			<argument index="4" name="data" type="PackedByteArray" />
-			<description>
-				Emitted when a network despawn request has been received from a client, or for a [PackedScene] that has been configured as [constant REPLICATION_MODE_CUSTOM].
-			</description>
-		</signal>
-		<signal name="despawned">
-			<argument index="0" name="scene_id" type="int" />
-			<argument index="1" name="node" type="Node" />
-			<description>
-				Emitted on a client before deleting a local Node upon receiving a despawn request from the server.
-			</description>
-		</signal>
-		<signal name="replicated_instance_added">
-			<argument index="0" name="scene_id" type="int" />
-			<argument index="1" name="node" type="Node" />
-			<description>
-				Emitted when an instance of a [PackedScene] that has been configured for networking enters the [SceneTree]. See [method spawn_config].
-			</description>
-		</signal>
-		<signal name="replicated_instance_removed">
-			<argument index="0" name="scene_id" type="int" />
-			<argument index="1" name="node" type="Node" />
-			<description>
-				Emitted when an instance of a [PackedScene] that has been configured for networking leaves the [SceneTree]. See [method spawn_config].
-			</description>
-		</signal>
-		<signal name="spawn_requested">
-			<argument index="0" name="id" type="int" />
-			<argument index="1" name="scene_id" type="int" />
-			<argument index="2" name="parent" type="Node" />
-			<argument index="3" name="name" type="String" />
-			<argument index="4" name="data" type="PackedByteArray" />
-			<description>
-				Emitted when a network spawn request has been received from a client, or for a [PackedScene] that has been configured as [constant REPLICATION_MODE_CUSTOM].
-			</description>
-		</signal>
-		<signal name="spawned">
-			<argument index="0" name="scene_id" type="int" />
-			<argument index="1" name="node" type="Node" />
-			<description>
-				Emitted on a client after a new Node is instantiated locally and added to the SceneTree upon receiving a spawn request from the server.
-			</description>
-		</signal>
-	</signals>
-	<constants>
-		<constant name="REPLICATION_MODE_NONE" value="0" enum="ReplicationMode">
-			Used with [method spawn_config] to identify a [PackedScene] that should not be replicated.
-		</constant>
-		<constant name="REPLICATION_MODE_SERVER" value="1" enum="ReplicationMode">
-			Used with [method spawn_config] to identify a [PackedScene] that should be automatically replicated from server to clients.
-		</constant>
-		<constant name="REPLICATION_MODE_CUSTOM" value="2" enum="ReplicationMode">
-			Used with [method spawn_config] to identify a [PackedScene] that can be manually replicated among peers.
-		</constant>
-	</constants>
-</class>
diff --git a/doc/classes/MultiplayerSpawner.xml b/doc/classes/MultiplayerSpawner.xml
new file mode 100644
index 0000000000..8bfecfce41
--- /dev/null
+++ b/doc/classes/MultiplayerSpawner.xml
@@ -0,0 +1,47 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<class name="MultiplayerSpawner" inherits="Node" version="4.0">
+	<brief_description>
+	</brief_description>
+	<description>
+	</description>
+	<tutorials>
+	</tutorials>
+	<methods>
+		<method name="_spawn_custom" qualifiers="virtual">
+			<return type="Object" />
+			<argument index="0" name="data" type="Variant" />
+			<description>
+			</description>
+		</method>
+		<method name="spawn">
+			<return type="Node" />
+			<argument index="0" name="data" type="Variant" default="null" />
+			<description>
+			</description>
+		</method>
+	</methods>
+	<members>
+		<member name="auto_spawn" type="bool" setter="set_auto_spawning" getter="is_auto_spawning" default="false">
+		</member>
+		<member name="replication" type="PackedScene[]" setter="set_spawnable_scenes" getter="get_spawnable_scenes" default="[]">
+		</member>
+		<member name="spawn_limit" type="int" setter="set_spawn_limit" getter="get_spawn_limit" default="0">
+		</member>
+		<member name="spawn_path" type="NodePath" setter="set_spawn_path" getter="get_spawn_path" default="NodePath(&quot;&quot;)">
+		</member>
+	</members>
+	<signals>
+		<signal name="despawned">
+			<argument index="0" name="scene_id" type="int" />
+			<argument index="1" name="node" type="Node" />
+			<description>
+			</description>
+		</signal>
+		<signal name="spawned">
+			<argument index="0" name="scene_id" type="int" />
+			<argument index="1" name="node" type="Node" />
+			<description>
+			</description>
+		</signal>
+	</signals>
+</class>
diff --git a/doc/classes/MultiplayerSynchronizer.xml b/doc/classes/MultiplayerSynchronizer.xml
new file mode 100644
index 0000000000..242d4589a4
--- /dev/null
+++ b/doc/classes/MultiplayerSynchronizer.xml
@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<class name="MultiplayerSynchronizer" inherits="Node" version="4.0">
+	<brief_description>
+	</brief_description>
+	<description>
+	</description>
+	<tutorials>
+	</tutorials>
+	<members>
+		<member name="replication_interval" type="float" setter="set_replication_interval" getter="get_replication_interval" default="0.0">
+		</member>
+		<member name="resource" type="SceneReplicationConfig" setter="set_replication_config" getter="get_replication_config">
+		</member>
+		<member name="root_path" type="NodePath" setter="set_root_path" getter="get_root_path" default="NodePath(&quot;&quot;)">
+		</member>
+	</members>
+</class>
diff --git a/doc/classes/SceneReplicationConfig.xml b/doc/classes/SceneReplicationConfig.xml
new file mode 100644
index 0000000000..e846740dd3
--- /dev/null
+++ b/doc/classes/SceneReplicationConfig.xml
@@ -0,0 +1,61 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<class name="SceneReplicationConfig" inherits="Resource" version="4.0">
+	<brief_description>
+	</brief_description>
+	<description>
+	</description>
+	<tutorials>
+	</tutorials>
+	<methods>
+		<method name="add_property">
+			<return type="void" />
+			<argument index="0" name="path" type="NodePath" />
+			<argument index="1" name="index" type="int" default="-1" />
+			<description>
+			</description>
+		</method>
+		<method name="get_properties" qualifiers="const">
+			<return type="NodePath[]" />
+			<description>
+			</description>
+		</method>
+		<method name="property_get_index" qualifiers="const">
+			<return type="int" />
+			<argument index="0" name="path" type="NodePath" />
+			<description>
+			</description>
+		</method>
+		<method name="property_get_spawn">
+			<return type="bool" />
+			<argument index="0" name="path" type="NodePath" />
+			<description>
+			</description>
+		</method>
+		<method name="property_get_sync">
+			<return type="bool" />
+			<argument index="0" name="path" type="NodePath" />
+			<description>
+			</description>
+		</method>
+		<method name="property_set_spawn">
+			<return type="void" />
+			<argument index="0" name="path" type="NodePath" />
+			<argument index="1" name="enabled" type="bool" />
+			<description>
+			</description>
+		</method>
+		<method name="property_set_sync">
+			<return type="void" />
+			<argument index="0" name="path" type="NodePath" />
+			<argument index="1" name="enabled" type="bool" />
+			<description>
+			</description>
+		</method>
+		<method name="remove_property">
+			<return type="void" />
+			<argument index="0" name="path" type="NodePath" />
+			<description>
+			</description>
+		</method>
+	</methods>
+</class>
diff --git a/editor/editor_node.cpp b/editor/editor_node.cpp
index 716d4a50c3..c9417ee57c 100644
--- a/editor/editor_node.cpp
+++ b/editor/editor_node.cpp
@@ -162,6 +162,7 @@
 #include "editor/plugins/path_3d_editor_plugin.h"
 #include "editor/plugins/physical_bone_3d_editor_plugin.h"
 #include "editor/plugins/polygon_2d_editor_plugin.h"
+#include "editor/plugins/replication_editor_plugin.h"
 #include "editor/plugins/resource_preloader_editor_plugin.h"
 #include "editor/plugins/root_motion_editor_plugin.h"
 #include "editor/plugins/script_editor_plugin.h"
@@ -7021,6 +7022,7 @@ EditorNode::EditorNode() {
 	add_editor_plugin(memnew(InputEventEditorPlugin(this)));
 	add_editor_plugin(memnew(SubViewportPreviewEditorPlugin(this)));
 	add_editor_plugin(memnew(TextControlEditorPlugin(this)));
+	add_editor_plugin(memnew(ReplicationEditorPlugin(this)));
 
 	for (int i = 0; i < EditorPlugins::get_plugin_count(); i++) {
 		add_editor_plugin(EditorPlugins::create(i, this));
diff --git a/editor/plugins/replication_editor_plugin.cpp b/editor/plugins/replication_editor_plugin.cpp
new file mode 100644
index 0000000000..93f4a853f3
--- /dev/null
+++ b/editor/plugins/replication_editor_plugin.cpp
@@ -0,0 +1,390 @@
+/*************************************************************************/
+/*  replication_editor_plugin.cpp                                        */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#include "replication_editor_plugin.h"
+
+#include "editor/editor_scale.h"
+#include "editor/inspector_dock.h"
+#include "scene/gui/dialogs.h"
+#include "scene/gui/tree.h"
+#include "scene/multiplayer/multiplayer_synchronizer.h"
+
+/// ReplicationEditor
+ReplicationEditor::ReplicationEditor(EditorNode *p_editor) {
+	editor = p_editor;
+	set_v_size_flags(SIZE_EXPAND_FILL);
+	set_custom_minimum_size(Size2(0, 200) * EDSCALE);
+
+	delete_dialog = memnew(ConfirmationDialog);
+	delete_dialog->connect("cancelled", callable_mp(this, &ReplicationEditor::_dialog_closed), varray(false));
+	delete_dialog->connect("confirmed", callable_mp(this, &ReplicationEditor::_dialog_closed), varray(true));
+	add_child(delete_dialog);
+
+	error_dialog = memnew(AcceptDialog);
+	error_dialog->get_ok_button()->set_text(TTR("Close"));
+	error_dialog->set_title(TTR("Error!"));
+	add_child(error_dialog);
+
+	VBoxContainer *vb = memnew(VBoxContainer);
+	vb->set_v_size_flags(SIZE_EXPAND_FILL);
+	add_child(vb);
+
+	HBoxContainer *hb = memnew(HBoxContainer);
+	vb->add_child(hb);
+	np_line_edit = memnew(LineEdit);
+	np_line_edit->set_placeholder(":property");
+	np_line_edit->set_h_size_flags(SIZE_EXPAND_FILL);
+	hb->add_child(np_line_edit);
+	add_button = memnew(Button);
+	add_button->connect("pressed", callable_mp(this, &ReplicationEditor::_add_pressed));
+	add_button->set_text(TTR("Add"));
+	hb->add_child(add_button);
+
+	tree = memnew(Tree);
+	tree->set_hide_root(true);
+	tree->set_columns(4);
+	tree->set_column_titles_visible(true);
+	tree->set_column_title(0, TTR("Properties"));
+	tree->set_column_expand(0, true);
+	tree->set_column_title(1, TTR("Spawn"));
+	tree->set_column_expand(1, false);
+	tree->set_column_custom_minimum_width(1, 100);
+	tree->set_column_title(2, TTR("Sync"));
+	tree->set_column_custom_minimum_width(2, 100);
+	tree->set_column_expand(2, false);
+	tree->set_column_expand(3, false);
+	tree->create_item();
+	tree->connect("button_pressed", callable_mp(this, &ReplicationEditor::_tree_button_pressed));
+	tree->connect("item_edited", callable_mp(this, &ReplicationEditor::_tree_item_edited));
+	tree->set_v_size_flags(SIZE_EXPAND_FILL);
+	vb->add_child(tree);
+}
+
+void ReplicationEditor::_bind_methods() {
+	ClassDB::bind_method(D_METHOD("_update_config"), &ReplicationEditor::_update_config);
+	ClassDB::bind_method(D_METHOD("_update_checked", "property", "column", "checked"), &ReplicationEditor::_update_checked);
+	ADD_SIGNAL(MethodInfo("keying_changed"));
+}
+
+void ReplicationEditor::_notification(int p_what) {
+	if (p_what == NOTIFICATION_ENTER_TREE || p_what == EditorSettings::NOTIFICATION_EDITOR_SETTINGS_CHANGED) {
+		add_theme_style_override("panel", editor->get_gui_base()->get_theme_stylebox(SNAME("panel"), SNAME("Panel")));
+	} else if (p_what == NOTIFICATION_VISIBILITY_CHANGED) {
+		update_keying();
+	}
+}
+
+void ReplicationEditor::_add_pressed() {
+	if (!current) {
+		error_dialog->set_text(TTR("Please select a MultiplayerSynchronizer first."));
+		error_dialog->popup_centered();
+		return;
+	}
+	if (current->get_root_path().is_empty()) {
+		error_dialog->set_text(TTR("The MultiplayerSynchronizer needs a root path."));
+		error_dialog->popup_centered();
+		return;
+	}
+	String np_text = np_line_edit->get_text();
+	if (np_text.find(":") == -1) {
+		np_text = ":" + np_text;
+	}
+	NodePath prop = NodePath(np_text);
+	if (prop.is_empty()) {
+		return;
+	}
+	UndoRedo *undo_redo = editor->get_undo_redo();
+	undo_redo->create_action(TTR("Add property"));
+	config = current->get_replication_config();
+	if (config.is_null()) {
+		config.instantiate();
+		current->set_replication_config(config);
+		undo_redo->add_do_method(current, "set_replication_config", config);
+		undo_redo->add_undo_method(current, "set_replication_config", Ref<SceneReplicationConfig>());
+		_update_config();
+	}
+	undo_redo->add_do_method(config.ptr(), "add_property", prop);
+	undo_redo->add_undo_method(config.ptr(), "remove_property", prop);
+	undo_redo->add_do_method(this, "_update_config");
+	undo_redo->add_undo_method(this, "_update_config");
+	undo_redo->commit_action();
+}
+
+void ReplicationEditor::_tree_item_edited() {
+	TreeItem *ti = tree->get_edited();
+	if (!ti || config.is_null()) {
+		return;
+	}
+	int column = tree->get_edited_column();
+	ERR_FAIL_COND(column < 1 || column > 2);
+	const NodePath prop = ti->get_metadata(0);
+	UndoRedo *undo_redo = editor->get_undo_redo();
+	bool value = ti->is_checked(column);
+	String method;
+	if (column == 1) {
+		undo_redo->create_action(TTR("Set spawn property"));
+		method = "property_set_spawn";
+	} else {
+		undo_redo->create_action(TTR("Set sync property"));
+		method = "property_set_sync";
+	}
+	undo_redo->add_do_method(config.ptr(), method, prop, value);
+	undo_redo->add_undo_method(config.ptr(), method, prop, !value);
+	undo_redo->add_do_method(this, "_update_checked", prop, column, value);
+	undo_redo->add_undo_method(this, "_update_checked", prop, column, !value);
+	undo_redo->commit_action();
+}
+
+void ReplicationEditor::_tree_button_pressed(Object *p_item, int p_column, int p_id) {
+	TreeItem *ti = Object::cast_to<TreeItem>(p_item);
+	if (!ti) {
+		return;
+	}
+	deleting = ti->get_metadata(0);
+	delete_dialog->set_text(TTR("Delete Property?") + "\n\"" + ti->get_text(0) + "\"");
+	delete_dialog->popup_centered();
+}
+
+void ReplicationEditor::_dialog_closed(bool p_confirmed) {
+	if (deleting.is_empty() || config.is_null()) {
+		return;
+	}
+	if (p_confirmed) {
+		const NodePath prop = deleting;
+		int idx = config->property_get_index(prop);
+		bool spawn = config->property_get_spawn(prop);
+		bool sync = config->property_get_sync(prop);
+		UndoRedo *undo_redo = editor->get_undo_redo();
+		undo_redo->create_action(TTR("Remove Property"));
+		undo_redo->add_do_method(config.ptr(), "remove_property", prop);
+		undo_redo->add_undo_method(config.ptr(), "add_property", prop, idx);
+		undo_redo->add_undo_method(config.ptr(), "property_set_spawn", prop, spawn);
+		undo_redo->add_undo_method(config.ptr(), "property_set_sync", prop, sync);
+		undo_redo->add_do_method(this, "_update_config");
+		undo_redo->add_undo_method(this, "_update_config");
+		undo_redo->commit_action();
+	}
+	deleting = NodePath();
+}
+
+void ReplicationEditor::_update_checked(const NodePath &p_prop, int p_column, bool p_checked) {
+	if (!tree->get_root()) {
+		return;
+	}
+	TreeItem *ti = tree->get_root()->get_first_child();
+	while (ti) {
+		if (ti->get_metadata(0).operator NodePath() == p_prop) {
+			ti->set_checked(p_column, p_checked);
+			return;
+		}
+		ti = ti->get_next();
+	}
+}
+
+void ReplicationEditor::update_keying() {
+	/// TODO make keying usable.
+#if 0
+	bool keying_enabled = false;
+	EditorHistory *editor_history = EditorNode::get_singleton()->get_editor_history();
+	if (is_visible_in_tree() && config.is_valid() && editor_history->get_path_size() > 0) {
+		Object *obj = ObjectDB::get_instance(editor_history->get_path_object(0));
+		keying_enabled = Object::cast_to<Node>(obj) != nullptr;
+	}
+
+	if (keying_enabled == keying) {
+		return;
+	}
+
+	keying = keying_enabled;
+	emit_signal(SNAME("keying_changed"));
+#endif
+}
+
+void ReplicationEditor::_update_config() {
+	deleting = NodePath();
+	tree->clear();
+	tree->create_item();
+	if (!config.is_valid()) {
+		update_keying();
+		return;
+	}
+	TypedArray<NodePath> props = config->get_properties();
+	for (int i = 0; i < props.size(); i++) {
+		const NodePath path = props[i];
+		_add_property(path, config->property_get_spawn(path), config->property_get_sync(path));
+	}
+	update_keying();
+}
+
+void ReplicationEditor::edit(MultiplayerSynchronizer *p_sync) {
+	if (current == p_sync) {
+		return;
+	}
+	current = p_sync;
+	if (current) {
+		config = current->get_replication_config();
+	} else {
+		config.unref();
+	}
+	_update_config();
+}
+
+Ref<Texture2D> ReplicationEditor::_get_class_icon(const Node *p_node) {
+	if (!p_node || !has_theme_icon(p_node->get_class(), "EditorIcons")) {
+		return get_theme_icon("ImportFail", "EditorIcons");
+	}
+	return get_theme_icon(p_node->get_class(), "EditorIcons");
+}
+
+void ReplicationEditor::_add_property(const NodePath &p_property, bool p_spawn, bool p_sync) {
+	String prop = String(p_property);
+	TreeItem *item = tree->create_item();
+	item->set_selectable(0, false);
+	item->set_selectable(1, false);
+	item->set_selectable(2, false);
+	item->set_selectable(3, false);
+	item->set_text(0, prop);
+	item->set_metadata(0, prop);
+	Node *root_node = current && !current->get_root_path().is_empty() ? current->get_node(current->get_root_path()) : nullptr;
+	Ref<Texture2D> icon = _get_class_icon(root_node);
+	if (root_node) {
+		String path = prop.substr(0, prop.find(":"));
+		String subpath = prop.substr(path.size());
+		Node *node = root_node->get_node_or_null(path);
+		if (!node) {
+			node = root_node;
+		}
+		item->set_text(0, String(node->get_name()) + ":" + subpath);
+		icon = _get_class_icon(node);
+	}
+	item->set_icon(0, icon);
+	item->add_button(3, get_theme_icon("Remove", "EditorIcons"));
+	item->set_text_alignment(1, HORIZONTAL_ALIGNMENT_CENTER);
+	item->set_cell_mode(1, TreeItem::CELL_MODE_CHECK);
+	item->set_checked(1, p_spawn);
+	item->set_editable(1, true);
+	item->set_text_alignment(2, HORIZONTAL_ALIGNMENT_CENTER);
+	item->set_cell_mode(2, TreeItem::CELL_MODE_CHECK);
+	item->set_checked(2, p_sync);
+	item->set_editable(2, true);
+}
+
+void ReplicationEditor::property_keyed(const String &p_property) {
+	ERR_FAIL_COND(!current || config.is_null());
+	Node *root = current->get_node(current->get_root_path());
+	ERR_FAIL_COND(!root);
+	EditorHistory *history = editor->get_editor_history();
+	ERR_FAIL_COND(history->get_path_size() == 0);
+	Node *node = Object::cast_to<Node>(ObjectDB::get_instance(history->get_path_object(0)));
+	ERR_FAIL_COND(!node);
+	if (node->is_class("MultiplayerSynchronizer")) {
+		error_dialog->set_text(TTR("Properties of 'MultiplayerSynchronizer' cannot be configured for replication."));
+		error_dialog->popup_centered();
+		return;
+	}
+	if (history->get_path_size() > 1 || p_property.get_slice_count(":") > 1) {
+		error_dialog->set_text(TTR("Subresources cannot yet be configured for replication."));
+		error_dialog->popup_centered();
+		return;
+	}
+
+	String path = root->get_path_to(node);
+	for (int i = 1; i < history->get_path_size(); i++) {
+		String prop = history->get_path_property(i);
+		ERR_FAIL_COND(prop == "");
+		path += ":" + prop;
+	}
+	path += ":" + p_property;
+
+	NodePath prop = path;
+	UndoRedo *undo_redo = editor->get_undo_redo();
+	undo_redo->create_action(TTR("Add property"));
+	undo_redo->add_do_method(config.ptr(), "add_property", prop);
+	undo_redo->add_undo_method(config.ptr(), "remove_property", prop);
+	undo_redo->add_do_method(this, "_update_config");
+	undo_redo->add_undo_method(this, "_update_config");
+	undo_redo->commit_action();
+}
+
+/// ReplicationEditorPlugin
+ReplicationEditorPlugin::ReplicationEditorPlugin(EditorNode *p_node) {
+	editor = p_node;
+	repl_editor = memnew(ReplicationEditor(editor));
+	editor->add_bottom_panel_item(TTR("Replication"), repl_editor);
+}
+
+ReplicationEditorPlugin::~ReplicationEditorPlugin() {
+}
+
+void ReplicationEditorPlugin::_keying_changed() {
+	// TODO make lock usable.
+	//InspectorDock::get_inspector_singleton()->set_keying(repl_editor->has_keying(), this);
+}
+
+void ReplicationEditorPlugin::_property_keyed(const String &p_keyed, const Variant &p_value, bool p_advance) {
+	if (!repl_editor->has_keying()) {
+		return;
+	}
+	repl_editor->property_keyed(p_keyed);
+}
+
+void ReplicationEditorPlugin::_notification(int p_what) {
+	if (p_what == NOTIFICATION_ENTER_TREE) {
+		//Node3DEditor::get_singleton()->connect("transform_key_request", callable_mp(this, &AnimationPlayerEditorPlugin::_transform_key_request));
+		InspectorDock::get_inspector_singleton()->connect("property_keyed", callable_mp(this, &ReplicationEditorPlugin::_property_keyed));
+		repl_editor->connect("keying_changed", callable_mp(this, &ReplicationEditorPlugin::_keying_changed));
+		// TODO make lock usable.
+		//InspectorDock::get_inspector_singleton()->connect("object_inspected", callable_mp(repl_editor, &ReplicationEditor::update_keying));
+		get_tree()->connect("node_removed", callable_mp(this, &ReplicationEditorPlugin::_node_removed));
+	}
+}
+
+void ReplicationEditorPlugin::_node_removed(Node *p_node) {
+	if (p_node && p_node == repl_editor->get_current()) {
+		repl_editor->edit(nullptr);
+		if (repl_editor->is_visible_in_tree()) {
+			editor->hide_bottom_panel();
+		}
+	}
+}
+
+void ReplicationEditorPlugin::edit(Object *p_object) {
+	repl_editor->edit(Object::cast_to<MultiplayerSynchronizer>(p_object));
+}
+
+bool ReplicationEditorPlugin::handles(Object *p_object) const {
+	return p_object->is_class("MultiplayerSynchronizer");
+}
+
+void ReplicationEditorPlugin::make_visible(bool p_visible) {
+	if (p_visible) {
+		editor->make_bottom_panel_item_visible(repl_editor);
+	}
+}
diff --git a/editor/plugins/replication_editor_plugin.h b/editor/plugins/replication_editor_plugin.h
new file mode 100644
index 0000000000..049eda99cc
--- /dev/null
+++ b/editor/plugins/replication_editor_plugin.h
@@ -0,0 +1,108 @@
+/*************************************************************************/
+/*  replication_editor_plugin.h                                          */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#ifndef REPLICATION_EDITOR_PLUGIN_H
+#define REPLICATION_EDITOR_PLUGIN_H
+
+#include "editor/editor_node.h"
+#include "editor/editor_plugin.h"
+#include "scene/resources/scene_replication_config.h"
+
+class ConfirmationDialog;
+class MultiplayerSynchronizer;
+class Tree;
+
+class ReplicationEditor : public VBoxContainer {
+	GDCLASS(ReplicationEditor, VBoxContainer);
+
+private:
+	EditorNode *editor;
+	MultiplayerSynchronizer *current = nullptr;
+
+	AcceptDialog *error_dialog = nullptr;
+	ConfirmationDialog *delete_dialog = nullptr;
+	Button *add_button = nullptr;
+	LineEdit *np_line_edit = nullptr;
+
+	Ref<SceneReplicationConfig> config;
+	NodePath deleting;
+	Tree *tree;
+	bool keying = false;
+
+	Ref<Texture2D> _get_class_icon(const Node *p_node);
+
+	void _add_pressed();
+	void _tree_item_edited();
+	void _tree_button_pressed(Object *p_item, int p_column, int p_id);
+	void _update_checked(const NodePath &p_prop, int p_column, bool p_checked);
+	void _update_config();
+	void _dialog_closed(bool p_confirmed);
+	void _add_property(const NodePath &p_property, bool p_spawn = true, bool p_sync = true);
+
+protected:
+	static void _bind_methods();
+
+	void _notification(int p_what);
+
+public:
+	void update_keying();
+	void edit(MultiplayerSynchronizer *p_object);
+	bool has_keying() const { return keying; }
+	MultiplayerSynchronizer *get_current() const { return current; }
+	void property_keyed(const String &p_property);
+
+	ReplicationEditor(EditorNode *p_node);
+	~ReplicationEditor() {}
+};
+
+class ReplicationEditorPlugin : public EditorPlugin {
+	GDCLASS(ReplicationEditorPlugin, EditorPlugin);
+
+private:
+	EditorNode *editor;
+	ReplicationEditor *repl_editor;
+
+	void _node_removed(Node *p_node);
+	void _keying_changed();
+	void _property_keyed(const String &p_keyed, const Variant &p_value, bool p_advance);
+
+protected:
+	void _notification(int p_what);
+
+public:
+	virtual void edit(Object *p_object) override;
+	virtual bool handles(Object *p_object) const override;
+	virtual void make_visible(bool p_visible) override;
+
+	ReplicationEditorPlugin(EditorNode *p_node);
+	~ReplicationEditorPlugin();
+};
+
+#endif // REPLICATION_EDITOR_PLUGIN_H
diff --git a/modules/gltf/gltf_document.cpp b/modules/gltf/gltf_document.cpp
index e54e51eb8d..baa39a3b80 100644
--- a/modules/gltf/gltf_document.cpp
+++ b/modules/gltf/gltf_document.cpp
@@ -50,6 +50,7 @@
 #include "core/io/file_access.h"
 #include "core/io/file_access_memory.h"
 #include "core/io/json.h"
+#include "core/io/stream_peer.h"
 #include "core/math/disjoint_set.h"
 #include "core/math/vector2.h"
 #include "core/variant/dictionary.h"
diff --git a/scene/SCsub b/scene/SCsub
index 92288211bb..a7b23af598 100644
--- a/scene/SCsub
+++ b/scene/SCsub
@@ -9,6 +9,7 @@ env.add_source_files(env.scene_sources, "*.cpp")
 
 # Chain load SCsubs
 SConscript("main/SCsub")
+SConscript("multiplayer/SCsub")
 SConscript("gui/SCsub")
 if not env["disable_3d"]:
     SConscript("3d/SCsub")
diff --git a/scene/main/node.cpp b/scene/main/node.cpp
index 149382bc2a..6b9d8ab211 100644
--- a/scene/main/node.cpp
+++ b/scene/main/node.cpp
@@ -32,6 +32,7 @@
 
 #include "core/core_string_names.h"
 #include "core/io/resource_loader.h"
+#include "core/multiplayer/multiplayer_api.h"
 #include "core/object/message_queue.h"
 #include "core/string/print_string.h"
 #include "instance_placeholder.h"
@@ -110,9 +111,6 @@ void Node::_notification(int p_notification) {
 				memdelete(data.path_cache);
 				data.path_cache = nullptr;
 			}
-			if (data.scene_file_path.length()) {
-				get_multiplayer()->scene_enter_exit_notify(data.scene_file_path, this, false);
-			}
 		} break;
 		case NOTIFICATION_PATH_RENAMED: {
 			if (data.path_cache) {
@@ -141,12 +139,6 @@ void Node::_notification(int p_notification) {
 			}
 
 			GDVIRTUAL_CALL(_ready);
-
-			if (data.scene_file_path.length()) {
-				ERR_FAIL_COND(!is_inside_tree());
-				get_multiplayer()->scene_enter_exit_notify(data.scene_file_path, this, true);
-			}
-
 		} break;
 		case NOTIFICATION_POSTINITIALIZE: {
 			data.in_constructor = false;
diff --git a/scene/main/node.h b/scene/main/node.h
index a1fc672a15..0ac10f4381 100644
--- a/scene/main/node.h
+++ b/scene/main/node.h
@@ -212,7 +212,6 @@ protected:
 	static String _get_name_num_separator();
 
 	friend class SceneState;
-	friend class MultiplayerReplicator;
 
 	void _add_child_nocheck(Node *p_child, const StringName &p_name);
 	void _set_owner_nocheck(Node *p_owner);
@@ -467,7 +466,7 @@ public:
 	bool is_displayed_folded() const;
 	/* NETWORK */
 
-	void set_multiplayer_authority(int p_peer_id, bool p_recursive = true);
+	virtual void set_multiplayer_authority(int p_peer_id, bool p_recursive = true);
 	int get_multiplayer_authority() const;
 	bool is_multiplayer_authority() const;
 
diff --git a/scene/main/scene_tree.cpp b/scene/main/scene_tree.cpp
index 45f04b28b9..0e4a6a4b5c 100644
--- a/scene/main/scene_tree.cpp
+++ b/scene/main/scene_tree.cpp
@@ -36,6 +36,7 @@
 #include "core/io/dir_access.h"
 #include "core/io/marshalls.h"
 #include "core/io/resource_loader.h"
+#include "core/multiplayer/multiplayer_api.h"
 #include "core/object/message_queue.h"
 #include "core/os/keyboard.h"
 #include "core/os/os.h"
diff --git a/scene/main/scene_tree.h b/scene/main/scene_tree.h
index 1dff1dab4f..a5cd52b4ca 100644
--- a/scene/main/scene_tree.h
+++ b/scene/main/scene_tree.h
@@ -31,7 +31,6 @@
 #ifndef SCENE_TREE_H
 #define SCENE_TREE_H
 
-#include "core/multiplayer/multiplayer_api.h"
 #include "core/os/main_loop.h"
 #include "core/os/thread_safe.h"
 #include "core/templates/self_list.h"
@@ -46,6 +45,7 @@ class Node;
 class Window;
 class Material;
 class Mesh;
+class MultiplayerAPI;
 class SceneDebugger;
 class Tween;
 
diff --git a/scene/multiplayer/SCsub b/scene/multiplayer/SCsub
new file mode 100644
index 0000000000..fc61250247
--- /dev/null
+++ b/scene/multiplayer/SCsub
@@ -0,0 +1,5 @@
+#!/usr/bin/env python
+
+Import("env")
+
+env.add_source_files(env.scene_sources, "*.cpp")
diff --git a/scene/multiplayer/multiplayer_spawner.cpp b/scene/multiplayer/multiplayer_spawner.cpp
new file mode 100644
index 0000000000..4f2a9d9e83
--- /dev/null
+++ b/scene/multiplayer/multiplayer_spawner.cpp
@@ -0,0 +1,227 @@
+/*************************************************************************/
+/*  multiplayer_spawner.cpp                                              */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#include "multiplayer_spawner.h"
+
+#include "core/io/marshalls.h"
+#include "core/multiplayer/multiplayer_api.h"
+#include "scene/main/window.h"
+#include "scene/scene_string_names.h"
+
+void MultiplayerSpawner::_bind_methods() {
+	ClassDB::bind_method(D_METHOD("spawn", "data"), &MultiplayerSpawner::spawn, DEFVAL(Variant()));
+
+	ClassDB::bind_method(D_METHOD("get_spawnable_scenes"), &MultiplayerSpawner::get_spawnable_scenes);
+	ClassDB::bind_method(D_METHOD("set_spawnable_scenes", "scenes"), &MultiplayerSpawner::set_spawnable_scenes);
+	ADD_PROPERTY(PropertyInfo(Variant::ARRAY, "replication", PROPERTY_HINT_ARRAY_TYPE, vformat("%s/%s:%s", Variant::OBJECT, PROPERTY_HINT_RESOURCE_TYPE, "PackedScene"), (PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_SCRIPT_VARIABLE)), "set_spawnable_scenes", "get_spawnable_scenes");
+
+	ClassDB::bind_method(D_METHOD("get_spawn_path"), &MultiplayerSpawner::get_spawn_path);
+	ClassDB::bind_method(D_METHOD("set_spawn_path", "path"), &MultiplayerSpawner::set_spawn_path);
+	ADD_PROPERTY(PropertyInfo(Variant::NODE_PATH, "spawn_path", PROPERTY_HINT_NONE, ""), "set_spawn_path", "get_spawn_path");
+
+	ClassDB::bind_method(D_METHOD("get_spawn_limit"), &MultiplayerSpawner::get_spawn_limit);
+	ClassDB::bind_method(D_METHOD("set_spawn_limit", "limit"), &MultiplayerSpawner::set_spawn_limit);
+	ADD_PROPERTY(PropertyInfo(Variant::INT, "spawn_limit", PROPERTY_HINT_RANGE, "0,1024,1,or_greater"), "set_spawn_limit", "get_spawn_limit");
+
+	ClassDB::bind_method(D_METHOD("set_auto_spawning", "enabled"), &MultiplayerSpawner::set_auto_spawning);
+	ClassDB::bind_method(D_METHOD("is_auto_spawning"), &MultiplayerSpawner::is_auto_spawning);
+	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "auto_spawn"), "set_auto_spawning", "is_auto_spawning");
+
+	GDVIRTUAL_BIND(_spawn_custom, "data");
+
+	ADD_SIGNAL(MethodInfo("despawned", PropertyInfo(Variant::INT, "scene_id"), PropertyInfo(Variant::OBJECT, "node", PROPERTY_HINT_RESOURCE_TYPE, "Node")));
+	ADD_SIGNAL(MethodInfo("spawned", PropertyInfo(Variant::INT, "scene_id"), PropertyInfo(Variant::OBJECT, "node", PROPERTY_HINT_RESOURCE_TYPE, "Node")));
+}
+
+void MultiplayerSpawner::_update_spawn_node() {
+#ifdef TOOLS_ENABLED
+	if (Engine::get_singleton()->is_editor_hint()) {
+		return;
+	}
+#endif
+	if (spawn_node.is_valid()) {
+		Node *node = Object::cast_to<Node>(ObjectDB::get_instance(spawn_node));
+		if (node && node->is_connected("child_entered_tree", callable_mp(this, &MultiplayerSpawner::_node_added))) {
+			node->disconnect("child_entered_tree", callable_mp(this, &MultiplayerSpawner::_node_added));
+		}
+	}
+	Node *node = spawn_path.is_empty() && is_inside_tree() ? nullptr : get_node_or_null(spawn_path);
+	if (node) {
+		spawn_node = node->get_instance_id();
+		if (auto_spawn) {
+			node->connect("child_entered_tree", callable_mp(this, &MultiplayerSpawner::_node_added));
+		}
+	} else {
+		spawn_node = ObjectID();
+	}
+}
+
+void MultiplayerSpawner::_notification(int p_what) {
+	if (p_what == NOTIFICATION_POST_ENTER_TREE) {
+		_update_spawn_node();
+	} else if (p_what == NOTIFICATION_EXIT_TREE) {
+		_update_spawn_node();
+		const ObjectID *oid = nullptr;
+		while ((oid = tracked_nodes.next(oid))) {
+			Node *node = Object::cast_to<Node>(ObjectDB::get_instance(*oid));
+			ERR_CONTINUE(!node);
+			node->disconnect(SceneStringNames::get_singleton()->tree_exiting, callable_mp(this, &MultiplayerSpawner::_node_exit));
+			// This is unlikely, but might still crash the engine.
+			if (node->is_connected(SceneStringNames::get_singleton()->ready, callable_mp(this, &MultiplayerSpawner::_node_ready))) {
+				node->disconnect(SceneStringNames::get_singleton()->ready, callable_mp(this, &MultiplayerSpawner::_node_ready));
+			}
+			get_multiplayer()->despawn(node, this);
+		}
+		tracked_nodes.clear();
+	}
+}
+
+void MultiplayerSpawner::_node_added(Node *p_node) {
+	if (!get_multiplayer()->has_multiplayer_peer() || !is_multiplayer_authority()) {
+		return;
+	}
+	if (tracked_nodes.has(p_node->get_instance_id())) {
+		return;
+	}
+	const Node *parent = get_spawn_node();
+	if (!parent || p_node->get_parent() != parent) {
+		return;
+	}
+	int id = get_scene_id(p_node->get_scene_file_path());
+	if (id == INVALID_ID) {
+		return;
+	}
+	const String name = p_node->get_name();
+	ERR_FAIL_COND_MSG(name.validate_node_name() != name, vformat("Unable to auto-spawn node with reserved name: %s. Make sure to add your replicated scenes via 'add_child(node, true)' to produce valid names.", name));
+	_track(p_node, Variant(), id);
+}
+
+void MultiplayerSpawner::set_auto_spawning(bool p_enabled) {
+	auto_spawn = p_enabled;
+	_update_spawn_node();
+}
+
+bool MultiplayerSpawner::is_auto_spawning() const {
+	return auto_spawn;
+}
+
+TypedArray<PackedScene> MultiplayerSpawner::get_spawnable_scenes() {
+	return spawnable_scenes;
+}
+
+void MultiplayerSpawner::set_spawnable_scenes(TypedArray<PackedScene> p_scenes) {
+	spawnable_scenes = p_scenes;
+}
+
+NodePath MultiplayerSpawner::get_spawn_path() const {
+	return spawn_path;
+}
+
+void MultiplayerSpawner::set_spawn_path(const NodePath &p_path) {
+	spawn_path = p_path;
+	_update_spawn_node();
+}
+
+void MultiplayerSpawner::_track(Node *p_node, const Variant &p_argument, int p_scene_id) {
+	ObjectID oid = p_node->get_instance_id();
+	if (!tracked_nodes.has(oid)) {
+		tracked_nodes[oid] = SpawnInfo(p_argument.duplicate(true), p_scene_id);
+		p_node->connect(SceneStringNames::get_singleton()->tree_exiting, callable_mp(this, &MultiplayerSpawner::_node_exit), varray(p_node->get_instance_id()), CONNECT_ONESHOT);
+		p_node->connect(SceneStringNames::get_singleton()->ready, callable_mp(this, &MultiplayerSpawner::_node_ready), varray(p_node->get_instance_id()), CONNECT_ONESHOT);
+	}
+}
+
+void MultiplayerSpawner::_node_ready(ObjectID p_id) {
+	get_multiplayer()->spawn(ObjectDB::get_instance(p_id), this);
+}
+
+void MultiplayerSpawner::_node_exit(ObjectID p_id) {
+	Node *node = Object::cast_to<Node>(ObjectDB::get_instance(p_id));
+	ERR_FAIL_COND(!node);
+	if (tracked_nodes.has(p_id)) {
+		tracked_nodes.erase(p_id);
+		get_multiplayer()->despawn(node, this);
+	}
+}
+
+int MultiplayerSpawner::get_scene_id(const String &p_scene) const {
+	for (int i = 0; i < spawnable_scenes.size(); i++) {
+		Ref<PackedScene> ps = spawnable_scenes[i];
+		ERR_CONTINUE(ps.is_null());
+		if (ps->get_path() == p_scene) {
+			return i;
+		}
+	}
+	return INVALID_ID;
+}
+
+int MultiplayerSpawner::get_spawn_id(const ObjectID &p_id) const {
+	const SpawnInfo *info = tracked_nodes.getptr(p_id);
+	return info ? info->id : INVALID_ID;
+}
+
+const Variant MultiplayerSpawner::get_spawn_argument(const ObjectID &p_id) const {
+	const SpawnInfo *info = tracked_nodes.getptr(p_id);
+	return info ? info->args : Variant();
+}
+
+Node *MultiplayerSpawner::instantiate_scene(int p_id) {
+	ERR_FAIL_COND_V_MSG(spawn_limit && spawn_limit <= tracked_nodes.size(), nullptr, "Spawn limit reached!");
+	ERR_FAIL_INDEX_V(p_id, spawnable_scenes.size(), nullptr);
+	Ref<PackedScene> scene = spawnable_scenes[p_id];
+	ERR_FAIL_COND_V(scene.is_null(), nullptr);
+	return scene->instantiate();
+}
+
+Node *MultiplayerSpawner::instantiate_custom(const Variant &p_data) {
+	ERR_FAIL_COND_V_MSG(spawn_limit && spawn_limit <= tracked_nodes.size(), nullptr, "Spawn limit reached!");
+	Object *obj = nullptr;
+	Node *node = nullptr;
+	if (GDVIRTUAL_CALL(_spawn_custom, p_data, obj)) {
+		node = Object::cast_to<Node>(obj);
+	}
+	return node;
+}
+
+Node *MultiplayerSpawner::spawn(const Variant &p_data) {
+	ERR_FAIL_COND_V(!is_inside_tree() || !get_multiplayer()->has_multiplayer_peer() || !is_multiplayer_authority(), nullptr);
+	ERR_FAIL_COND_V_MSG(spawn_limit && spawn_limit <= tracked_nodes.size(), nullptr, "Spawn limit reached!");
+	ERR_FAIL_COND_V_MSG(!GDVIRTUAL_IS_OVERRIDDEN(_spawn_custom), nullptr, "Custom spawn requires the '_spawn_custom' virtual method to be implemented via script.");
+
+	Node *parent = get_spawn_node();
+	ERR_FAIL_COND_V_MSG(!parent, nullptr, "Cannot find spawn node.");
+
+	Node *node = instantiate_custom(p_data);
+	ERR_FAIL_COND_V_MSG(!node, nullptr, "The '_spawn_custom' implementation must return a valid Node.");
+
+	_track(node, p_data);
+	parent->add_child(node, true);
+	return node;
+}
diff --git a/scene/multiplayer/multiplayer_spawner.h b/scene/multiplayer/multiplayer_spawner.h
new file mode 100644
index 0000000000..63948e39a5
--- /dev/null
+++ b/scene/multiplayer/multiplayer_spawner.h
@@ -0,0 +1,101 @@
+/*************************************************************************/
+/*  multiplayer_spawner.h                                                */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#ifndef MULTIPLAYER_SPAWNER_H
+#define MULTIPLAYER_SPAWNER_H
+
+#include "scene/main/node.h"
+
+#include "core/variant/typed_array.h"
+#include "scene/resources/packed_scene.h"
+#include "scene/resources/scene_replication_config.h"
+
+class MultiplayerSpawner : public Node {
+	GDCLASS(MultiplayerSpawner, Node);
+
+public:
+	enum {
+		INVALID_ID = 0xFF,
+	};
+
+private:
+	TypedArray<PackedScene> spawnable_scenes;
+	Set<ResourceUID::ID> spawnable_ids;
+	NodePath spawn_path;
+
+	struct SpawnInfo {
+		Variant args;
+		int id = INVALID_ID;
+		SpawnInfo(Variant p_args, int p_id) {
+			id = p_id;
+			args = p_args;
+		}
+		SpawnInfo() {}
+	};
+
+	ObjectID spawn_node;
+	HashMap<ObjectID, SpawnInfo> tracked_nodes;
+	bool auto_spawn = false;
+	uint32_t spawn_limit = 0;
+
+	void _update_spawn_node();
+	void _track(Node *p_node, const Variant &p_argument, int p_scene_id = INVALID_ID);
+	void _node_added(Node *p_node);
+	void _node_exit(ObjectID p_id);
+	void _node_ready(ObjectID p_id);
+
+protected:
+	static void _bind_methods();
+	void _notification(int p_what);
+
+public:
+	Node *get_spawn_node() const { return spawn_node.is_valid() ? Object::cast_to<Node>(ObjectDB::get_instance(spawn_node)) : nullptr; }
+	TypedArray<PackedScene> get_spawnable_scenes();
+	void set_spawnable_scenes(TypedArray<PackedScene> p_scenes);
+	NodePath get_spawn_path() const;
+	void set_spawn_path(const NodePath &p_path);
+	uint32_t get_spawn_limit() const { return spawn_limit; }
+	void set_spawn_limit(uint32_t p_limit) { spawn_limit = p_limit; }
+	bool is_auto_spawning() const;
+	void set_auto_spawning(bool p_enabled);
+
+	const Variant get_spawn_argument(const ObjectID &p_id) const;
+	int get_spawn_id(const ObjectID &p_id) const;
+	int get_scene_id(const String &p_path) const;
+	Node *spawn(const Variant &p_data = Variant());
+	Node *instantiate_custom(const Variant &p_data);
+	Node *instantiate_scene(int p_idx);
+
+	GDVIRTUAL1R(Object *, _spawn_custom, const Variant &);
+
+	MultiplayerSpawner() {}
+};
+
+#endif // MULTIPLAYER_SPAWNER_H
diff --git a/scene/multiplayer/multiplayer_synchronizer.cpp b/scene/multiplayer/multiplayer_synchronizer.cpp
new file mode 100644
index 0000000000..fbe1b99cc9
--- /dev/null
+++ b/scene/multiplayer/multiplayer_synchronizer.cpp
@@ -0,0 +1,158 @@
+/*************************************************************************/
+/*  multiplayer_synchronizer.cpp                                         */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#include "multiplayer_synchronizer.h"
+
+#include "core/config/engine.h"
+#include "core/multiplayer/multiplayer_api.h"
+
+Object *MultiplayerSynchronizer::_get_prop_target(Object *p_obj, const NodePath &p_path) {
+	if (p_path.get_name_count() == 0) {
+		return p_obj;
+	}
+	Node *node = Object::cast_to<Node>(p_obj);
+	ERR_FAIL_COND_V_MSG(!node || !node->has_node(p_path), nullptr, vformat("Node '%s' not found.", p_path));
+	return node->get_node(p_path);
+}
+
+void MultiplayerSynchronizer::_stop() {
+	Node *node = is_inside_tree() ? get_node_or_null(root_path) : nullptr;
+	if (node) {
+		get_multiplayer()->replication_stop(node, this);
+	}
+}
+
+void MultiplayerSynchronizer::_start() {
+	Node *node = is_inside_tree() ? get_node_or_null(root_path) : nullptr;
+	if (node) {
+		get_multiplayer()->replication_start(node, this);
+	}
+}
+
+Error MultiplayerSynchronizer::get_state(const List<NodePath> &p_properties, Object *p_obj, Vector<Variant> &r_variant, Vector<const Variant *> &r_variant_ptrs) {
+	ERR_FAIL_COND_V(!p_obj, ERR_INVALID_PARAMETER);
+	r_variant.resize(p_properties.size());
+	r_variant_ptrs.resize(r_variant.size());
+	int i = 0;
+	for (const NodePath &prop : p_properties) {
+		bool valid = false;
+		const Object *obj = _get_prop_target(p_obj, prop);
+		ERR_FAIL_COND_V(!obj, FAILED);
+		r_variant.write[i] = obj->get(prop.get_concatenated_subnames(), &valid);
+		r_variant_ptrs.write[i] = &r_variant[i];
+		ERR_FAIL_COND_V_MSG(!valid, ERR_INVALID_DATA, vformat("Property '%s' not found.", prop));
+		i++;
+	}
+	return OK;
+}
+
+Error MultiplayerSynchronizer::set_state(const List<NodePath> &p_properties, Object *p_obj, const Vector<Variant> &p_state) {
+	ERR_FAIL_COND_V(!p_obj, ERR_INVALID_PARAMETER);
+	int i = 0;
+	for (const NodePath &prop : p_properties) {
+		Object *obj = _get_prop_target(p_obj, prop);
+		ERR_FAIL_COND_V(!obj, FAILED);
+		obj->set(prop.get_concatenated_subnames(), p_state[i]);
+		i += 1;
+	}
+	return OK;
+}
+
+void MultiplayerSynchronizer::_bind_methods() {
+	ClassDB::bind_method(D_METHOD("set_root_path", "path"), &MultiplayerSynchronizer::set_root_path);
+	ClassDB::bind_method(D_METHOD("get_root_path"), &MultiplayerSynchronizer::get_root_path);
+	ADD_PROPERTY(PropertyInfo(Variant::NODE_PATH, "root_path"), "set_root_path", "get_root_path");
+
+	ClassDB::bind_method(D_METHOD("set_replication_interval", "milliseconds"), &MultiplayerSynchronizer::set_replication_interval);
+	ClassDB::bind_method(D_METHOD("get_replication_interval"), &MultiplayerSynchronizer::get_replication_interval);
+	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "replication_interval", PROPERTY_HINT_RANGE, "0,5,0.001"), "set_replication_interval", "get_replication_interval");
+
+	ClassDB::bind_method(D_METHOD("set_replication_config", "config"), &MultiplayerSynchronizer::set_replication_config);
+	ClassDB::bind_method(D_METHOD("get_replication_config"), &MultiplayerSynchronizer::get_replication_config);
+	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "resource", PROPERTY_HINT_RESOURCE_TYPE, "SceneReplicationConfig"), "set_replication_config", "get_replication_config");
+}
+
+void MultiplayerSynchronizer::_notification(int p_what) {
+#ifdef TOOLS_ENABLED
+	if (Engine::get_singleton()->is_editor_hint()) {
+		return;
+	}
+#endif
+	if (root_path.is_empty()) {
+		return;
+	}
+	if (p_what == NOTIFICATION_ENTER_TREE) {
+		_start();
+	} else if (p_what == NOTIFICATION_EXIT_TREE) {
+		_stop();
+	}
+}
+
+void MultiplayerSynchronizer::set_replication_interval(double p_interval) {
+	ERR_FAIL_COND_MSG(p_interval < 0, "Interval must be greater or equal to 0 (where 0 means default)");
+	interval_msec = uint64_t(p_interval * 1000);
+}
+
+double MultiplayerSynchronizer::get_replication_interval() const {
+	return double(interval_msec) / 1000.0;
+}
+
+uint64_t MultiplayerSynchronizer::get_replication_interval_msec() const {
+	return interval_msec;
+}
+
+void MultiplayerSynchronizer::set_replication_config(Ref<SceneReplicationConfig> p_config) {
+	replication_config = p_config;
+}
+
+Ref<SceneReplicationConfig> MultiplayerSynchronizer::get_replication_config() {
+	return replication_config;
+}
+
+void MultiplayerSynchronizer::set_root_path(const NodePath &p_path) {
+	_stop();
+	root_path = p_path;
+	_start();
+}
+
+NodePath MultiplayerSynchronizer::get_root_path() const {
+	return root_path;
+}
+
+void MultiplayerSynchronizer::set_multiplayer_authority(int p_peer_id, bool p_recursive) {
+	Node *node = is_inside_tree() ? get_node_or_null(root_path) : nullptr;
+	if (!node) {
+		Node::set_multiplayer_authority(p_peer_id, p_recursive);
+		return;
+	}
+	get_multiplayer()->replication_stop(node, this);
+	Node::set_multiplayer_authority(p_peer_id, p_recursive);
+	get_multiplayer()->replication_start(node, this);
+}
diff --git a/scene/multiplayer/multiplayer_synchronizer.h b/scene/multiplayer/multiplayer_synchronizer.h
new file mode 100644
index 0000000000..e856745379
--- /dev/null
+++ b/scene/multiplayer/multiplayer_synchronizer.h
@@ -0,0 +1,72 @@
+/*************************************************************************/
+/*  multiplayer_synchronizer.h                                           */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#ifndef MULTIPLAYER_SYNCHRONIZER_H
+#define MULTIPLAYER_SYNCHRONIZER_H
+
+#include "scene/main/node.h"
+
+#include "scene/resources/scene_replication_config.h"
+
+class MultiplayerSynchronizer : public Node {
+	GDCLASS(MultiplayerSynchronizer, Node);
+
+private:
+	Ref<SceneReplicationConfig> replication_config;
+	NodePath root_path;
+	uint64_t interval_msec = 0;
+
+	static Object *_get_prop_target(Object *p_obj, const NodePath &p_prop);
+	void _start();
+	void _stop();
+
+protected:
+	static void _bind_methods();
+	void _notification(int p_what);
+
+public:
+	static Error get_state(const List<NodePath> &p_properties, Object *p_obj, Vector<Variant> &r_variant, Vector<const Variant *> &r_variant_ptrs);
+	static Error set_state(const List<NodePath> &p_properties, Object *p_obj, const Vector<Variant> &p_state);
+
+	void set_replication_interval(double p_interval);
+	double get_replication_interval() const;
+	uint64_t get_replication_interval_msec() const;
+
+	void set_replication_config(Ref<SceneReplicationConfig> p_config);
+	Ref<SceneReplicationConfig> get_replication_config();
+
+	void set_root_path(const NodePath &p_path);
+	NodePath get_root_path() const;
+	virtual void set_multiplayer_authority(int p_peer_id, bool p_recursive = true) override;
+
+	MultiplayerSynchronizer() {}
+};
+
+#endif // MULTIPLAYER_SYNCHRONIZER_H
diff --git a/scene/multiplayer/scene_replication_interface.cpp b/scene/multiplayer/scene_replication_interface.cpp
new file mode 100644
index 0000000000..7155935084
--- /dev/null
+++ b/scene/multiplayer/scene_replication_interface.cpp
@@ -0,0 +1,415 @@
+/*************************************************************************/
+/*  scene_replication_interface.cpp                                      */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#include "scene_replication_interface.h"
+
+#include "core/io/marshalls.h"
+#include "scene/main/node.h"
+#include "scene/multiplayer/multiplayer_spawner.h"
+#include "scene/multiplayer/multiplayer_synchronizer.h"
+
+#define MAKE_ROOM(m_amount)             \
+	if (packet_cache.size() < m_amount) \
+		packet_cache.resize(m_amount);
+
+MultiplayerReplicationInterface *SceneReplicationInterface::_create(MultiplayerAPI *p_multiplayer) {
+	return memnew(SceneReplicationInterface(p_multiplayer));
+}
+
+void SceneReplicationInterface::make_default() {
+	MultiplayerAPI::create_default_replication_interface = _create;
+}
+
+void SceneReplicationInterface::_free_remotes(int p_id) {
+	const HashMap<uint32_t, ObjectID> remotes = rep_state->peer_get_remotes(p_id);
+	const uint32_t *k = nullptr;
+	while ((k = remotes.next(k))) {
+		Node *node = rep_state->get_node(remotes.get(*k));
+		ERR_CONTINUE(!node);
+		node->queue_delete();
+	}
+}
+
+void SceneReplicationInterface::on_peer_change(int p_id, bool p_connected) {
+	if (p_connected) {
+		rep_state->on_peer_change(p_id, p_connected);
+		for (const ObjectID &oid : rep_state->get_spawned_nodes()) {
+			_send_spawn(rep_state->get_node(oid), rep_state->get_spawner(oid), p_id);
+		}
+		for (const ObjectID &oid : rep_state->get_path_only_nodes()) {
+			Node *node = rep_state->get_node(oid);
+			MultiplayerSynchronizer *sync = rep_state->get_synchronizer(oid);
+			ERR_CONTINUE(!node || !sync);
+			if (sync->is_multiplayer_authority()) {
+				rep_state->peer_add_node(p_id, oid);
+			}
+		}
+	} else {
+		_free_remotes(p_id);
+		rep_state->on_peer_change(p_id, p_connected);
+	}
+}
+
+void SceneReplicationInterface::on_reset() {
+	for (int pid : rep_state->get_peers()) {
+		_free_remotes(pid);
+	}
+	rep_state->reset();
+}
+
+void SceneReplicationInterface::on_network_process() {
+	uint64_t msec = OS::get_singleton()->get_ticks_msec();
+	for (int peer : rep_state->get_peers()) {
+		_send_sync(peer, msec);
+	}
+}
+
+Error SceneReplicationInterface::on_spawn(Object *p_obj, Variant p_config) {
+	Node *node = Object::cast_to<Node>(p_obj);
+	ERR_FAIL_COND_V(!node || p_config.get_type() != Variant::OBJECT, ERR_INVALID_PARAMETER);
+	MultiplayerSpawner *spawner = Object::cast_to<MultiplayerSpawner>(p_config.get_validated_object());
+	ERR_FAIL_COND_V(!spawner, ERR_INVALID_PARAMETER);
+	Error err = rep_state->config_add_spawn(node, spawner);
+	ERR_FAIL_COND_V(err != OK, err);
+	return _send_spawn(node, spawner, 0);
+}
+
+Error SceneReplicationInterface::on_despawn(Object *p_obj, Variant p_config) {
+	Node *node = Object::cast_to<Node>(p_obj);
+	ERR_FAIL_COND_V(!node || p_config.get_type() != Variant::OBJECT, ERR_INVALID_PARAMETER);
+	MultiplayerSpawner *spawner = Object::cast_to<MultiplayerSpawner>(p_config.get_validated_object());
+	ERR_FAIL_COND_V(!p_obj || !spawner, ERR_INVALID_PARAMETER);
+	Error err = rep_state->config_del_spawn(node, spawner);
+	ERR_FAIL_COND_V(err != OK, err);
+	return _send_despawn(node, 0);
+}
+
+Error SceneReplicationInterface::on_replication_start(Object *p_obj, Variant p_config) {
+	Node *node = Object::cast_to<Node>(p_obj);
+	ERR_FAIL_COND_V(!node || p_config.get_type() != Variant::OBJECT, ERR_INVALID_PARAMETER);
+	MultiplayerSynchronizer *sync = Object::cast_to<MultiplayerSynchronizer>(p_config.get_validated_object());
+	ERR_FAIL_COND_V(!sync, ERR_INVALID_PARAMETER);
+	rep_state->config_add_sync(node, sync);
+	// Try to apply initial state if spawning (hack to apply if before ready).
+	if (pending_spawn == p_obj->get_instance_id()) {
+		pending_spawn = ObjectID(); // Make sure this only happens once.
+		const List<NodePath> props = sync->get_replication_config()->get_spawn_properties();
+		Vector<Variant> vars;
+		vars.resize(props.size());
+		int consumed;
+		Error err = MultiplayerAPI::decode_and_decompress_variants(vars, pending_buffer, pending_buffer_size, consumed);
+		ERR_FAIL_COND_V(err, err);
+		err = MultiplayerSynchronizer::set_state(props, node, vars);
+		ERR_FAIL_COND_V(err, err);
+	} else if (multiplayer->has_multiplayer_peer() && sync->is_multiplayer_authority()) {
+		// Either it's a spawn or a static sync, in any case add it to the list of known nodes.
+		rep_state->peer_add_node(0, p_obj->get_instance_id());
+	}
+	return OK;
+}
+
+Error SceneReplicationInterface::on_replication_stop(Object *p_obj, Variant p_config) {
+	Node *node = Object::cast_to<Node>(p_obj);
+	ERR_FAIL_COND_V(!node || p_config.get_type() != Variant::OBJECT, ERR_INVALID_PARAMETER);
+	MultiplayerSynchronizer *sync = Object::cast_to<MultiplayerSynchronizer>(p_config.get_validated_object());
+	ERR_FAIL_COND_V(!p_obj || !sync, ERR_INVALID_PARAMETER);
+	return rep_state->config_del_sync(node, sync);
+}
+
+Error SceneReplicationInterface::_send_raw(const uint8_t *p_buffer, int p_size, int p_peer, bool p_reliable) {
+	ERR_FAIL_COND_V(!p_buffer || p_size < 1, ERR_INVALID_PARAMETER);
+	ERR_FAIL_COND_V(!multiplayer, ERR_UNCONFIGURED);
+	ERR_FAIL_COND_V(!multiplayer->has_multiplayer_peer(), ERR_UNCONFIGURED);
+	Ref<MultiplayerPeer> peer = multiplayer->get_multiplayer_peer();
+	peer->set_target_peer(p_peer);
+	peer->set_transfer_channel(0);
+	peer->set_transfer_mode(p_reliable ? Multiplayer::TRANSFER_MODE_RELIABLE : Multiplayer::TRANSFER_MODE_UNRELIABLE);
+	return peer->put_packet(p_buffer, p_size);
+}
+
+Error SceneReplicationInterface::_send_spawn(Node *p_node, MultiplayerSpawner *p_spawner, int p_peer) {
+	ERR_FAIL_COND_V(p_peer < 0, ERR_BUG);
+	ERR_FAIL_COND_V(!multiplayer, ERR_BUG);
+	ERR_FAIL_COND_V(!p_spawner || !p_node, ERR_BUG);
+
+	const ObjectID oid = p_node->get_instance_id();
+	uint32_t nid = rep_state->ensure_net_id(oid);
+
+	// Prepare custom arg and scene_id
+	uint8_t scene_id = p_spawner->get_spawn_id(oid);
+	bool is_custom = scene_id == MultiplayerSpawner::INVALID_ID;
+	Variant spawn_arg = p_spawner->get_spawn_argument(oid);
+	int spawn_arg_size = 0;
+	if (is_custom) {
+		Error err = MultiplayerAPI::encode_and_compress_variant(spawn_arg, nullptr, spawn_arg_size, false);
+		ERR_FAIL_COND_V(err, err);
+	}
+
+	// Prepare spawn state.
+	int state_size = 0;
+	Vector<Variant> state_vars;
+	Vector<const Variant *> state_varp;
+	MultiplayerSynchronizer *synchronizer = rep_state->get_synchronizer(oid);
+	if (synchronizer && synchronizer->get_replication_config().is_valid()) {
+		const List<NodePath> props = synchronizer->get_replication_config()->get_spawn_properties();
+		Error err = MultiplayerSynchronizer::get_state(props, p_node, state_vars, state_varp);
+		ERR_FAIL_COND_V_MSG(err != OK, err, "Unable to retrieve spawn state.");
+		err = MultiplayerAPI::encode_and_compress_variants(state_varp.ptrw(), state_varp.size(), nullptr, state_size);
+		ERR_FAIL_COND_V_MSG(err != OK, err, "Unable to encode spawn state.");
+	}
+
+	// Prepare simplified path.
+	const Node *root_node = multiplayer->get_root_node();
+	ERR_FAIL_COND_V(!root_node, ERR_UNCONFIGURED);
+	NodePath rel_path = (root_node->get_path()).rel_path_to(p_spawner->get_path());
+
+	int path_id = 0;
+	multiplayer->send_confirm_path(p_spawner, rel_path, p_peer, path_id);
+
+	// Encode name and parent ID.
+	CharString cname = p_node->get_name().operator String().utf8();
+	int nlen = encode_cstring(cname.get_data(), nullptr);
+	MAKE_ROOM(1 + 1 + 4 + 4 + 4 + nlen + (is_custom ? 4 + spawn_arg_size : 0) + state_size);
+	uint8_t *ptr = packet_cache.ptrw();
+	ptr[0] = (uint8_t)MultiplayerAPI::NETWORK_COMMAND_SPAWN;
+	ptr[1] = scene_id;
+	int ofs = 2;
+	ofs += encode_uint32(path_id, &ptr[ofs]);
+	ofs += encode_uint32(nid, &ptr[ofs]);
+	ofs += encode_uint32(nlen, &ptr[ofs]);
+	ofs += encode_cstring(cname.get_data(), &ptr[ofs]);
+	// Write args
+	if (is_custom) {
+		ofs += encode_uint32(spawn_arg_size, &ptr[ofs]);
+		Error err = MultiplayerAPI::encode_and_compress_variant(spawn_arg, &ptr[ofs], spawn_arg_size, false);
+		ERR_FAIL_COND_V(err, err);
+		ofs += spawn_arg_size;
+	}
+	// Write state.
+	if (state_size) {
+		Error err = MultiplayerAPI::encode_and_compress_variants(state_varp.ptrw(), state_varp.size(), &ptr[ofs], state_size);
+		ERR_FAIL_COND_V(err, err);
+		ofs += state_size;
+	}
+	Error err = _send_raw(ptr, ofs, p_peer, true);
+	ERR_FAIL_COND_V(err, err);
+	return rep_state->peer_add_node(p_peer, oid);
+}
+
+Error SceneReplicationInterface::_send_despawn(Node *p_node, int p_peer) {
+	const ObjectID oid = p_node->get_instance_id();
+	MAKE_ROOM(5);
+	uint8_t *ptr = packet_cache.ptrw();
+	ptr[0] = (uint8_t)MultiplayerAPI::NETWORK_COMMAND_DESPAWN;
+	int ofs = 1;
+	uint32_t nid = rep_state->get_net_id(oid);
+	ofs += encode_uint32(nid, &ptr[ofs]);
+	Error err = _send_raw(ptr, ofs, p_peer, true);
+	ERR_FAIL_COND_V(err, err);
+	return rep_state->peer_del_node(p_peer, oid);
+}
+
+Error SceneReplicationInterface::on_spawn_receive(int p_from, const uint8_t *p_buffer, int p_buffer_len) {
+	ERR_FAIL_COND_V_MSG(p_buffer_len < 14, ERR_INVALID_DATA, "Invalid spawn packet received");
+	int ofs = 1; // The spawn/despawn command.
+	uint8_t scene_id = p_buffer[ofs];
+	ofs += 1;
+	uint32_t node_target = decode_uint32(&p_buffer[ofs]);
+	ofs += 4;
+	MultiplayerSpawner *spawner = Object::cast_to<MultiplayerSpawner>(multiplayer->get_cached_node(p_from, node_target));
+	ERR_FAIL_COND_V(!spawner, ERR_DOES_NOT_EXIST);
+	ERR_FAIL_COND_V(p_from != spawner->get_multiplayer_authority(), ERR_UNAUTHORIZED);
+
+	uint32_t net_id = decode_uint32(&p_buffer[ofs]);
+	ofs += 4;
+	uint32_t name_len = decode_uint32(&p_buffer[ofs]);
+	ofs += 4;
+	ERR_FAIL_COND_V_MSG(name_len > uint32_t(p_buffer_len - ofs), ERR_INVALID_DATA, vformat("Invalid spawn packet size: %d, wants: %d", p_buffer_len, ofs + name_len));
+	ERR_FAIL_COND_V_MSG(name_len < 1, ERR_INVALID_DATA, "Zero spawn name size.");
+
+	// We need to make sure no trickery happens here, but we want to allow autogenerated ("@") node names.
+	const String name = String::utf8((const char *)&p_buffer[ofs], name_len);
+	ERR_FAIL_COND_V_MSG(name.validate_node_name() != name, ERR_INVALID_DATA, vformat("Invalid node name received: '%s'. Make sure to add nodes via 'add_child(node, true)' remotely.", name));
+	ofs += name_len;
+
+	// Check that we can spawn.
+	Node *parent = spawner->get_node_or_null(spawner->get_spawn_path());
+	ERR_FAIL_COND_V(!parent, ERR_UNCONFIGURED);
+	ERR_FAIL_COND_V(parent->has_node(name), ERR_INVALID_DATA);
+
+	Node *node = nullptr;
+	if (scene_id == MultiplayerSpawner::INVALID_ID) {
+		// Custom spawn.
+		ERR_FAIL_COND_V(p_buffer_len - ofs < 4, ERR_INVALID_DATA);
+		uint32_t arg_size = decode_uint32(&p_buffer[ofs]);
+		ofs += 4;
+		ERR_FAIL_COND_V(arg_size > uint32_t(p_buffer_len - ofs), ERR_INVALID_DATA);
+		Variant v;
+		Error err = MultiplayerAPI::decode_and_decompress_variant(v, &p_buffer[ofs], arg_size, nullptr, false);
+		ERR_FAIL_COND_V(err != OK, err);
+		ofs += arg_size;
+		node = spawner->instantiate_custom(v);
+	} else {
+		// Scene based spawn.
+		node = spawner->instantiate_scene(scene_id);
+	}
+	ERR_FAIL_COND_V(!node, ERR_UNAUTHORIZED);
+	node->set_name(name);
+	rep_state->peer_add_remote(p_from, net_id, node, spawner);
+	// The initial state will be applied during the sync config (i.e. before _ready).
+	int state_len = p_buffer_len - ofs;
+	if (state_len) {
+		pending_spawn = node->get_instance_id();
+		pending_buffer = &p_buffer[ofs];
+		pending_buffer_size = state_len;
+	}
+	parent->add_child(node);
+	pending_spawn = ObjectID();
+	pending_buffer = nullptr;
+	pending_buffer_size = 0;
+	return OK;
+}
+
+Error SceneReplicationInterface::on_despawn_receive(int p_from, const uint8_t *p_buffer, int p_buffer_len) {
+	ERR_FAIL_COND_V_MSG(p_buffer_len < 5, ERR_INVALID_DATA, "Invalid spawn packet received");
+	int ofs = 1; // The spawn/despawn command.
+	uint32_t net_id = decode_uint32(&p_buffer[ofs]);
+	ofs += 4;
+	Node *node = nullptr;
+	Error err = rep_state->peer_del_remote(p_from, net_id, &node);
+	ERR_FAIL_COND_V(err != OK, err);
+	ERR_FAIL_COND_V(!node, ERR_BUG);
+	node->queue_delete();
+	return OK;
+}
+
+void SceneReplicationInterface::_send_sync(int p_peer, uint64_t p_msec) {
+	const Set<ObjectID> &known = rep_state->get_known_nodes(p_peer);
+	if (known.is_empty()) {
+		return;
+	}
+	MAKE_ROOM(sync_mtu);
+	uint8_t *ptr = packet_cache.ptrw();
+	ptr[0] = MultiplayerAPI::NETWORK_COMMAND_SYNC;
+	int ofs = 1;
+	ofs += encode_uint16(rep_state->peer_sync_next(p_peer), &ptr[1]);
+	// Can only send updates for already notified nodes.
+	// This is a lazy implementation, we could optimize much more here with by grouping by replication config.
+	for (const ObjectID &oid : known) {
+		if (!rep_state->update_sync_time(oid, p_msec)) {
+			continue; // nothing to sync.
+		}
+		MultiplayerSynchronizer *sync = rep_state->get_synchronizer(oid);
+		ERR_CONTINUE(!sync);
+		Node *node = rep_state->get_node(oid);
+		ERR_CONTINUE(!node);
+		int size;
+		Vector<Variant> vars;
+		Vector<const Variant *> varp;
+		const List<NodePath> props = sync->get_replication_config()->get_sync_properties();
+		Error err = MultiplayerSynchronizer::get_state(props, node, vars, varp);
+		ERR_CONTINUE_MSG(err != OK, "Unable to retrieve sync state.");
+		err = MultiplayerAPI::encode_and_compress_variants(varp.ptrw(), varp.size(), nullptr, size);
+		ERR_CONTINUE_MSG(err != OK, "Unable to encode sync state.");
+		// TODO Handle single state above MTU.
+		ERR_CONTINUE_MSG(size > 3 + 4 + 4 + sync_mtu, vformat("Node states bigger then MTU will not be sent (%d > %d): %s", size, sync_mtu, node->get_path()));
+		if (ofs + 4 + 4 + size > sync_mtu) {
+			// Send what we got, and reset write.
+			_send_raw(packet_cache.ptr(), ofs, p_peer, false);
+			ofs = 3;
+		}
+		if (size) {
+			uint32_t net_id = rep_state->get_net_id(oid);
+			if (net_id == 0) {
+				// First time path based ID.
+				const Node *root_node = multiplayer->get_root_node();
+				ERR_FAIL_COND(!root_node);
+				NodePath rel_path = (root_node->get_path()).rel_path_to(sync->get_path());
+				int path_id = 0;
+				multiplayer->send_confirm_path(sync, rel_path, p_peer, path_id);
+				net_id = path_id;
+				rep_state->set_net_id(oid, net_id | 0x80000000);
+			}
+			ofs += encode_uint32(rep_state->get_net_id(oid), &ptr[ofs]);
+			ofs += encode_uint32(size, &ptr[ofs]);
+			MultiplayerAPI::encode_and_compress_variants(varp.ptrw(), varp.size(), &ptr[ofs], size);
+			ofs += size;
+		}
+	}
+	if (ofs > 3) {
+		// Got some left over to send.
+		_send_raw(packet_cache.ptr(), ofs, p_peer, false);
+	}
+}
+
+Error SceneReplicationInterface::on_sync_receive(int p_from, const uint8_t *p_buffer, int p_buffer_len) {
+	ERR_FAIL_COND_V_MSG(p_buffer_len < 11, ERR_INVALID_DATA, "Invalid sync packet received");
+	uint16_t time = decode_uint16(&p_buffer[1]);
+	int ofs = 3;
+	rep_state->peer_sync_recv(p_from, time);
+	while (ofs + 8 < p_buffer_len) {
+		uint32_t net_id = decode_uint32(&p_buffer[ofs]);
+		ofs += 4;
+		uint32_t size = decode_uint32(&p_buffer[ofs]);
+		ofs += 4;
+		Node *node = nullptr;
+		if (net_id & 0x80000000) {
+			MultiplayerSynchronizer *sync = Object::cast_to<MultiplayerSynchronizer>(multiplayer->get_cached_node(p_from, net_id & 0x7FFFFFFF));
+			ERR_FAIL_COND_V(!sync || sync->get_multiplayer_authority() != p_from, ERR_UNAUTHORIZED);
+			node = sync->get_node(sync->get_root_path());
+		} else {
+			node = rep_state->peer_get_remote(p_from, net_id);
+		}
+		if (!node) {
+			// Not received yet.
+			ofs += size;
+			continue;
+		}
+		const ObjectID oid = node->get_instance_id();
+		if (!rep_state->update_last_node_sync(oid, time)) {
+			// State is too old.
+			ofs += size;
+			continue;
+		}
+		MultiplayerSynchronizer *sync = rep_state->get_synchronizer(oid);
+		ERR_FAIL_COND_V(!sync, ERR_BUG);
+		ERR_FAIL_COND_V(size > uint32_t(p_buffer_len - ofs), ERR_BUG);
+		const List<NodePath> props = sync->get_replication_config()->get_sync_properties();
+		Vector<Variant> vars;
+		vars.resize(props.size());
+		int consumed;
+		Error err = MultiplayerAPI::decode_and_decompress_variants(vars, &p_buffer[ofs], size, consumed);
+		ERR_FAIL_COND_V(err, err);
+		err = MultiplayerSynchronizer::set_state(props, node, vars);
+		ERR_FAIL_COND_V(err, err);
+		ofs += size;
+	}
+	return OK;
+}
diff --git a/scene/multiplayer/scene_replication_interface.h b/scene/multiplayer/scene_replication_interface.h
new file mode 100644
index 0000000000..855878d029
--- /dev/null
+++ b/scene/multiplayer/scene_replication_interface.h
@@ -0,0 +1,84 @@
+/*************************************************************************/
+/*  scene_replication_interface.h                                        */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#ifndef SCENE_TREE_REPLICATOR_INTERFACE_H
+#define SCENE_TREE_REPLICATOR_INTERFACE_H
+
+#include "core/multiplayer/multiplayer_api.h"
+
+#include "scene/multiplayer/scene_replication_state.h"
+
+class SceneReplicationInterface : public MultiplayerReplicationInterface {
+	GDCLASS(SceneReplicationInterface, MultiplayerReplicationInterface);
+
+private:
+	void _send_sync(int p_peer, uint64_t p_msec);
+	Error _send_spawn(Node *p_node, MultiplayerSpawner *p_spawner, int p_peer);
+	Error _send_despawn(Node *p_node, int p_peer);
+	Error _send_raw(const uint8_t *p_buffer, int p_size, int p_peer, bool p_reliable);
+
+	void _free_remotes(int p_peer);
+
+	Ref<SceneReplicationState> rep_state;
+	MultiplayerAPI *multiplayer;
+	PackedByteArray packet_cache;
+	int sync_mtu = 1350; // Highly dependent on underlying protocol.
+
+	// An hack to apply the initial state before ready.
+	ObjectID pending_spawn;
+	const uint8_t *pending_buffer = nullptr;
+	int pending_buffer_size = 0;
+
+protected:
+	static MultiplayerReplicationInterface *_create(MultiplayerAPI *p_multiplayer);
+
+public:
+	static void make_default();
+
+	virtual void on_reset() override;
+	virtual void on_peer_change(int p_id, bool p_connected) override;
+
+	virtual Error on_spawn(Object *p_obj, Variant p_config) override;
+	virtual Error on_despawn(Object *p_obj, Variant p_config) override;
+	virtual Error on_replication_start(Object *p_obj, Variant p_config) override;
+	virtual Error on_replication_stop(Object *p_obj, Variant p_config) override;
+	virtual void on_network_process() override;
+
+	virtual Error on_spawn_receive(int p_from, const uint8_t *p_buffer, int p_buffer_len) override;
+	virtual Error on_despawn_receive(int p_from, const uint8_t *p_buffer, int p_buffer_len) override;
+	virtual Error on_sync_receive(int p_from, const uint8_t *p_buffer, int p_buffer_len) override;
+
+	SceneReplicationInterface(MultiplayerAPI *p_multiplayer) {
+		rep_state.instantiate();
+		multiplayer = p_multiplayer;
+	}
+};
+
+#endif // SCENE_TREE_REPLICATOR_INTERFACE_H
diff --git a/scene/multiplayer/scene_replication_state.cpp b/scene/multiplayer/scene_replication_state.cpp
new file mode 100644
index 0000000000..b8dadeff24
--- /dev/null
+++ b/scene/multiplayer/scene_replication_state.cpp
@@ -0,0 +1,258 @@
+/*************************************************************************/
+/*  scene_replication_state.cpp                                          */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#include "scene/multiplayer/scene_replication_state.h"
+
+#include "core/multiplayer/multiplayer_api.h"
+#include "scene/multiplayer/multiplayer_spawner.h"
+#include "scene/multiplayer/multiplayer_synchronizer.h"
+#include "scene/scene_string_names.h"
+
+SceneReplicationState::TrackedNode &SceneReplicationState::_track(const ObjectID &p_id) {
+	if (!tracked_nodes.has(p_id)) {
+		tracked_nodes[p_id] = TrackedNode(p_id);
+		Node *node = Object::cast_to<Node>(ObjectDB::get_instance(p_id));
+		node->connect(SceneStringNames::get_singleton()->tree_exited, callable_mp(this, &SceneReplicationState::_untrack), varray(p_id), Node::CONNECT_ONESHOT);
+	}
+	return tracked_nodes[p_id];
+}
+
+void SceneReplicationState::_untrack(const ObjectID &p_id) {
+	if (tracked_nodes.has(p_id)) {
+		uint32_t net_id = tracked_nodes[p_id].net_id;
+		uint32_t peer = tracked_nodes[p_id].remote_peer;
+		tracked_nodes.erase(p_id);
+		// If it was spawned by a remote, remove it from the received nodes.
+		if (peer && peers_info.has(peer)) {
+			peers_info[peer].recv_nodes.erase(net_id);
+		}
+		// If we spawned or synced it, we need to remove it from any peer it was sent to.
+		if (net_id || peer == 0) {
+			const int *k = nullptr;
+			while ((k = peers_info.next(k))) {
+				peers_info.get(*k).known_nodes.erase(p_id);
+			}
+		}
+	}
+}
+
+const HashMap<uint32_t, ObjectID> SceneReplicationState::peer_get_remotes(int p_peer) const {
+	return peers_info.has(p_peer) ? peers_info[p_peer].recv_nodes : HashMap<uint32_t, ObjectID>();
+}
+
+bool SceneReplicationState::update_last_node_sync(const ObjectID &p_id, uint16_t p_time) {
+	TrackedNode *tnode = tracked_nodes.getptr(p_id);
+	ERR_FAIL_COND_V(!tnode, false);
+	if (p_time <= tnode->last_sync && tnode->last_sync - p_time < 32767) {
+		return false;
+	}
+	tnode->last_sync = p_time;
+	return true;
+}
+
+bool SceneReplicationState::update_sync_time(const ObjectID &p_id, uint64_t p_msec) {
+	TrackedNode *tnode = tracked_nodes.getptr(p_id);
+	ERR_FAIL_COND_V(!tnode, false);
+	MultiplayerSynchronizer *sync = get_synchronizer(p_id);
+	if (!sync) {
+		return false;
+	}
+	if (tnode->last_sync_msec == p_msec) {
+		return true;
+	}
+	if (p_msec >= tnode->last_sync_msec + sync->get_replication_interval_msec()) {
+		tnode->last_sync_msec = p_msec;
+		return true;
+	}
+	return false;
+}
+
+const Set<ObjectID> SceneReplicationState::get_known_nodes(int p_peer) {
+	ERR_FAIL_COND_V(!peers_info.has(p_peer), Set<ObjectID>());
+	return peers_info[p_peer].known_nodes;
+}
+
+uint32_t SceneReplicationState::get_net_id(const ObjectID &p_id) const {
+	const TrackedNode *tnode = tracked_nodes.getptr(p_id);
+	ERR_FAIL_COND_V(!tnode, 0);
+	return tnode->net_id;
+}
+
+void SceneReplicationState::set_net_id(const ObjectID &p_id, uint32_t p_net_id) {
+	TrackedNode *tnode = tracked_nodes.getptr(p_id);
+	ERR_FAIL_COND(!tnode);
+	tnode->net_id = p_net_id;
+}
+
+uint32_t SceneReplicationState::ensure_net_id(const ObjectID &p_id) {
+	TrackedNode *tnode = tracked_nodes.getptr(p_id);
+	ERR_FAIL_COND_V(!tnode, 0);
+	if (tnode->net_id == 0) {
+		tnode->net_id = ++last_net_id;
+	}
+	return tnode->net_id;
+}
+
+void SceneReplicationState::on_peer_change(int p_peer, bool p_connected) {
+	if (p_connected) {
+		peers_info[p_peer] = PeerInfo();
+		known_peers.insert(p_peer);
+	} else {
+		peers_info.erase(p_peer);
+		known_peers.erase(p_peer);
+	}
+}
+
+void SceneReplicationState::reset() {
+	peers_info.clear();
+	known_peers.clear();
+	// Tracked nodes are cleared on deletion, here we only reset the ids so they can be later re-assigned.
+	const ObjectID *oid = nullptr;
+	while ((oid = tracked_nodes.next(oid))) {
+		TrackedNode &tobj = tracked_nodes[*oid];
+		tobj.net_id = 0;
+		tobj.remote_peer = 0;
+		tobj.last_sync = 0;
+	}
+}
+
+Error SceneReplicationState::config_add_spawn(Node *p_node, MultiplayerSpawner *p_spawner) {
+	const ObjectID oid = p_node->get_instance_id();
+	TrackedNode &tobj = _track(oid);
+	ERR_FAIL_COND_V(tobj.spawner != ObjectID(), ERR_ALREADY_IN_USE);
+	tobj.spawner = p_spawner->get_instance_id();
+	spawned_nodes.insert(oid);
+	// The spawner may be notified after the synchronizer.
+	path_only_nodes.erase(oid);
+	return OK;
+}
+
+Error SceneReplicationState::config_del_spawn(Node *p_node, MultiplayerSpawner *p_spawner) {
+	const ObjectID oid = p_node->get_instance_id();
+	ERR_FAIL_COND_V(!is_tracked(oid), ERR_INVALID_PARAMETER);
+	TrackedNode &tobj = _track(oid);
+	ERR_FAIL_COND_V(tobj.spawner != p_spawner->get_instance_id(), ERR_INVALID_PARAMETER);
+	tobj.spawner = ObjectID();
+	spawned_nodes.erase(oid);
+	return OK;
+}
+
+Error SceneReplicationState::config_add_sync(Node *p_node, MultiplayerSynchronizer *p_sync) {
+	const ObjectID oid = p_node->get_instance_id();
+	TrackedNode &tobj = _track(oid);
+	ERR_FAIL_COND_V(tobj.synchronizer != ObjectID(), ERR_ALREADY_IN_USE);
+	tobj.synchronizer = p_sync->get_instance_id();
+	// If it doesn't have a spawner, we might need to assign ID for this node using it's path.
+	if (tobj.spawner.is_null()) {
+		path_only_nodes.insert(oid);
+	}
+	return OK;
+}
+
+Error SceneReplicationState::config_del_sync(Node *p_node, MultiplayerSynchronizer *p_sync) {
+	const ObjectID oid = p_node->get_instance_id();
+	ERR_FAIL_COND_V(!is_tracked(oid), ERR_INVALID_PARAMETER);
+	TrackedNode &tobj = _track(oid);
+	ERR_FAIL_COND_V(tobj.synchronizer != p_sync->get_instance_id(), ERR_INVALID_PARAMETER);
+	tobj.synchronizer = ObjectID();
+	if (path_only_nodes.has(oid)) {
+		p_node->disconnect(SceneStringNames::get_singleton()->tree_exited, callable_mp(this, &SceneReplicationState::_untrack));
+		_untrack(oid);
+		path_only_nodes.erase(oid);
+	}
+	return OK;
+}
+
+Error SceneReplicationState::peer_add_node(int p_peer, const ObjectID &p_id) {
+	if (p_peer) {
+		ERR_FAIL_COND_V(!peers_info.has(p_peer), ERR_INVALID_PARAMETER);
+		peers_info[p_peer].known_nodes.insert(p_id);
+	} else {
+		const int *pid = nullptr;
+		while ((pid = peers_info.next(pid))) {
+			peers_info.get(*pid).known_nodes.insert(p_id);
+		}
+	}
+	return OK;
+}
+
+Error SceneReplicationState::peer_del_node(int p_peer, const ObjectID &p_id) {
+	if (p_peer) {
+		ERR_FAIL_COND_V(!peers_info.has(p_peer), ERR_INVALID_PARAMETER);
+		peers_info[p_peer].known_nodes.erase(p_id);
+	} else {
+		const int *pid = nullptr;
+		while ((pid = peers_info.next(pid))) {
+			peers_info.get(*pid).known_nodes.erase(p_id);
+		}
+	}
+	return OK;
+}
+
+Node *SceneReplicationState::peer_get_remote(int p_peer, uint32_t p_net_id) {
+	PeerInfo *info = peers_info.getptr(p_peer);
+	return info && info->recv_nodes.has(p_net_id) ? Object::cast_to<Node>(ObjectDB::get_instance(info->recv_nodes[p_net_id])) : nullptr;
+}
+
+Error SceneReplicationState::peer_add_remote(int p_peer, uint32_t p_net_id, Node *p_node, MultiplayerSpawner *p_spawner) {
+	ERR_FAIL_COND_V(!p_node || !p_spawner, ERR_INVALID_PARAMETER);
+	ERR_FAIL_COND_V(!peers_info.has(p_peer), ERR_UNAVAILABLE);
+	PeerInfo &pinfo = peers_info[p_peer];
+	ObjectID oid = p_node->get_instance_id();
+	TrackedNode &tobj = _track(oid);
+	tobj.spawner = p_spawner->get_instance_id();
+	tobj.net_id = p_net_id;
+	tobj.remote_peer = p_peer;
+	tobj.last_sync = pinfo.last_recv_sync;
+	// Also track as a remote.
+	ERR_FAIL_COND_V(pinfo.recv_nodes.has(p_net_id), ERR_ALREADY_IN_USE);
+	pinfo.recv_nodes[p_net_id] = oid;
+	return OK;
+}
+
+Error SceneReplicationState::peer_del_remote(int p_peer, uint32_t p_net_id, Node **r_node) {
+	ERR_FAIL_COND_V(!peers_info.has(p_peer), ERR_UNAUTHORIZED);
+	PeerInfo &info = peers_info[p_peer];
+	ERR_FAIL_COND_V(!info.recv_nodes.has(p_net_id), ERR_UNAUTHORIZED);
+	*r_node = Object::cast_to<Node>(ObjectDB::get_instance(info.recv_nodes[p_net_id]));
+	info.recv_nodes.erase(p_net_id);
+	return OK;
+}
+
+uint16_t SceneReplicationState::peer_sync_next(int p_peer) {
+	ERR_FAIL_COND_V(!peers_info.has(p_peer), 0);
+	PeerInfo &info = peers_info[p_peer];
+	return ++info.last_sent_sync;
+}
+
+void SceneReplicationState::peer_sync_recv(int p_peer, uint16_t p_time) {
+	ERR_FAIL_COND(!peers_info.has(p_peer));
+	peers_info[p_peer].last_recv_sync = p_time;
+}
diff --git a/scene/multiplayer/scene_replication_state.h b/scene/multiplayer/scene_replication_state.h
new file mode 100644
index 0000000000..18e4d9fa39
--- /dev/null
+++ b/scene/multiplayer/scene_replication_state.h
@@ -0,0 +1,121 @@
+/*************************************************************************/
+/*  scene_replication_state.h                                            */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#ifndef SCENE_REPLICATON_STATE_H
+#define SCENE_REPLICATON_STATE_H
+
+#include "core/object/ref_counted.h"
+
+class MultiplayerSpawner;
+class MultiplayerSynchronizer;
+class Node;
+
+class SceneReplicationState : public RefCounted {
+private:
+	struct TrackedNode {
+		ObjectID id;
+		uint32_t net_id = 0;
+		uint32_t remote_peer = 0;
+		ObjectID spawner;
+		ObjectID synchronizer;
+		uint16_t last_sync = 0;
+		uint64_t last_sync_msec = 0;
+
+		bool operator==(const ObjectID &p_other) { return id == p_other; }
+
+		Node *get_node() const { return id.is_valid() ? Object::cast_to<Node>(ObjectDB::get_instance(id)) : nullptr; }
+		MultiplayerSpawner *get_spawner() const { return spawner.is_valid() ? Object::cast_to<MultiplayerSpawner>(ObjectDB::get_instance(spawner)) : nullptr; }
+		MultiplayerSynchronizer *get_synchronizer() const { return synchronizer.is_valid() ? Object::cast_to<MultiplayerSynchronizer>(ObjectDB::get_instance(synchronizer)) : nullptr; }
+		TrackedNode() {}
+		TrackedNode(const ObjectID &p_id) { id = p_id; }
+		TrackedNode(const ObjectID &p_id, uint32_t p_net_id) {
+			id = p_id;
+			net_id = p_net_id;
+		}
+	};
+
+	struct PeerInfo {
+		Set<ObjectID> known_nodes;
+		HashMap<uint32_t, ObjectID> recv_nodes;
+		uint16_t last_sent_sync = 0;
+		uint16_t last_recv_sync = 0;
+	};
+
+	Set<int> known_peers;
+	uint32_t last_net_id = 0;
+	HashMap<ObjectID, TrackedNode> tracked_nodes;
+	HashMap<int, PeerInfo> peers_info;
+	Set<ObjectID> spawned_nodes;
+	Set<ObjectID> path_only_nodes;
+
+	TrackedNode &_track(const ObjectID &p_id);
+	void _untrack(const ObjectID &p_id);
+	bool is_tracked(const ObjectID &p_id) const { return tracked_nodes.has(p_id); }
+
+public:
+	const Set<int> get_peers() const { return known_peers; }
+	const Set<ObjectID> get_spawned_nodes() const { return spawned_nodes; }
+	const Set<ObjectID> get_path_only_nodes() const { return path_only_nodes; }
+
+	MultiplayerSynchronizer *get_synchronizer(const ObjectID &p_id) { return tracked_nodes.has(p_id) ? tracked_nodes[p_id].get_synchronizer() : nullptr; }
+	MultiplayerSpawner *get_spawner(const ObjectID &p_id) { return tracked_nodes.has(p_id) ? tracked_nodes[p_id].get_spawner() : nullptr; }
+	Node *get_node(const ObjectID &p_id) { return tracked_nodes.has(p_id) ? tracked_nodes[p_id].get_node() : nullptr; }
+	bool update_last_node_sync(const ObjectID &p_id, uint16_t p_time);
+	bool update_sync_time(const ObjectID &p_id, uint64_t p_msec);
+
+	const Set<ObjectID> get_known_nodes(int p_peer);
+	uint32_t get_net_id(const ObjectID &p_id) const;
+	void set_net_id(const ObjectID &p_id, uint32_t p_net_id);
+	uint32_t ensure_net_id(const ObjectID &p_id);
+
+	void reset();
+	void on_peer_change(int p_peer, bool p_connected);
+
+	Error config_add_spawn(Node *p_node, MultiplayerSpawner *p_spawner);
+	Error config_del_spawn(Node *p_node, MultiplayerSpawner *p_spawner);
+
+	Error config_add_sync(Node *p_node, MultiplayerSynchronizer *p_sync);
+	Error config_del_sync(Node *p_node, MultiplayerSynchronizer *p_sync);
+
+	Error peer_add_node(int p_peer, const ObjectID &p_id);
+	Error peer_del_node(int p_peer, const ObjectID &p_id);
+
+	const HashMap<uint32_t, ObjectID> peer_get_remotes(int p_peer) const;
+	Node *peer_get_remote(int p_peer, uint32_t p_net_id);
+	Error peer_add_remote(int p_peer, uint32_t p_net_id, Node *p_node, MultiplayerSpawner *p_spawner);
+	Error peer_del_remote(int p_peer, uint32_t p_net_id, Node **r_node);
+
+	uint16_t peer_sync_next(int p_peer);
+	void peer_sync_recv(int p_peer, uint16_t p_time);
+
+	SceneReplicationState() {}
+};
+
+#endif // SCENE_REPLICATON_STATE_H
diff --git a/scene/register_scene_types.cpp b/scene/register_scene_types.cpp
index 838cef824b..f19b018982 100644
--- a/scene/register_scene_types.cpp
+++ b/scene/register_scene_types.cpp
@@ -134,6 +134,9 @@
 #include "scene/main/timer.h"
 #include "scene/main/viewport.h"
 #include "scene/main/window.h"
+#include "scene/multiplayer/multiplayer_spawner.h"
+#include "scene/multiplayer/multiplayer_synchronizer.h"
+#include "scene/multiplayer/scene_replication_interface.h"
 #include "scene/resources/audio_stream_sample.h"
 #include "scene/resources/bit_map.h"
 #include "scene/resources/box_shape_3d.h"
@@ -301,6 +304,8 @@ void register_scene_types() {
 	GDREGISTER_CLASS(SubViewport);
 	GDREGISTER_CLASS(ViewportTexture);
 	GDREGISTER_CLASS(HTTPRequest);
+	GDREGISTER_CLASS(MultiplayerSpawner);
+	GDREGISTER_CLASS(MultiplayerSynchronizer);
 	GDREGISTER_CLASS(Timer);
 	GDREGISTER_CLASS(CanvasLayer);
 	GDREGISTER_CLASS(CanvasModulate);
@@ -822,6 +827,8 @@ void register_scene_types() {
 	GDREGISTER_CLASS(Font);
 	GDREGISTER_CLASS(Curve);
 
+	GDREGISTER_CLASS(SceneReplicationConfig);
+
 	GDREGISTER_CLASS(TextLine);
 	GDREGISTER_CLASS(TextParagraph);
 
@@ -1050,6 +1057,7 @@ void register_scene_types() {
 	}
 
 	SceneDebugger::initialize();
+	SceneReplicationInterface::make_default();
 
 	NativeExtensionManager::get_singleton()->initialize_extensions(NativeExtension::INITIALIZATION_LEVEL_SCENE);
 }
diff --git a/scene/resources/scene_replication_config.cpp b/scene/resources/scene_replication_config.cpp
new file mode 100644
index 0000000000..2acc0f1922
--- /dev/null
+++ b/scene/resources/scene_replication_config.cpp
@@ -0,0 +1,187 @@
+/*************************************************************************/
+/*  scene_replication_config.cpp                                         */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#include "scene_replication_config.h"
+
+#include "core/multiplayer/multiplayer_api.h"
+#include "scene/main/node.h"
+
+bool SceneReplicationConfig::_set(const StringName &p_name, const Variant &p_value) {
+	String name = p_name;
+
+	if (name.begins_with("properties/")) {
+		int idx = name.get_slicec('/', 1).to_int();
+		String what = name.get_slicec('/', 2);
+
+		if (properties.size() == idx && what == "path") {
+			ERR_FAIL_COND_V(p_value.get_type() != Variant::NODE_PATH, false);
+			NodePath path = p_value;
+			ERR_FAIL_COND_V(path.is_empty() || path.get_subname_count() == 0, false);
+			add_property(path);
+			return true;
+		}
+		ERR_FAIL_COND_V(p_value.get_type() != Variant::BOOL, false);
+		ERR_FAIL_INDEX_V(idx, properties.size(), false);
+		ReplicationProperty &prop = properties[idx];
+		if (what == "sync") {
+			prop.sync = p_value;
+			sync_props.push_back(prop.name);
+			return true;
+		} else if (what == "spawn") {
+			prop.spawn = p_value;
+			spawn_props.push_back(prop.name);
+			return true;
+		}
+	}
+	return false;
+}
+
+bool SceneReplicationConfig::_get(const StringName &p_name, Variant &r_ret) const {
+	String name = p_name;
+
+	if (name.begins_with("properties/")) {
+		int idx = name.get_slicec('/', 1).to_int();
+		String what = name.get_slicec('/', 2);
+		ERR_FAIL_INDEX_V(idx, properties.size(), false);
+		const ReplicationProperty &prop = properties[idx];
+		if (what == "path") {
+			r_ret = prop.name;
+			return true;
+		} else if (what == "sync") {
+			r_ret = prop.sync;
+			return true;
+		} else if (what == "spawn") {
+			r_ret = prop.spawn;
+			return true;
+		}
+	}
+	return false;
+}
+
+void SceneReplicationConfig::_get_property_list(List<PropertyInfo> *p_list) const {
+	for (int i = 0; i < properties.size(); i++) {
+		p_list->push_back(PropertyInfo(Variant::STRING, "properties/" + itos(i) + "/path", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_NO_EDITOR | PROPERTY_USAGE_INTERNAL));
+		p_list->push_back(PropertyInfo(Variant::STRING, "properties/" + itos(i) + "/spawn", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_NO_EDITOR | PROPERTY_USAGE_INTERNAL));
+		p_list->push_back(PropertyInfo(Variant::STRING, "properties/" + itos(i) + "/sync", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_NO_EDITOR | PROPERTY_USAGE_INTERNAL));
+	}
+}
+
+TypedArray<NodePath> SceneReplicationConfig::get_properties() const {
+	TypedArray<NodePath> paths;
+	for (const ReplicationProperty &prop : properties) {
+		paths.push_back(prop.name);
+	}
+	return paths;
+}
+
+void SceneReplicationConfig::add_property(const NodePath &p_path, int p_index) {
+	ERR_FAIL_COND(properties.find(p_path));
+
+	if (p_index < 0 || p_index == properties.size()) {
+		properties.push_back(ReplicationProperty(p_path));
+		return;
+	}
+
+	ERR_FAIL_INDEX(p_index, properties.size());
+
+	List<ReplicationProperty>::Element *I = properties.front();
+	int c = 0;
+	while (c < p_index) {
+		I = I->next();
+		c++;
+	}
+	properties.insert_before(I, ReplicationProperty(p_path));
+}
+
+void SceneReplicationConfig::remove_property(const NodePath &p_path) {
+	properties.erase(p_path);
+}
+
+int SceneReplicationConfig::property_get_index(const NodePath &p_path) const {
+	for (int i = 0; i < properties.size(); i++) {
+		if (properties[i].name == p_path) {
+			return i;
+		}
+	}
+	ERR_FAIL_V(-1);
+}
+
+bool SceneReplicationConfig::property_get_spawn(const NodePath &p_path) {
+	List<ReplicationProperty>::Element *E = properties.find(p_path);
+	ERR_FAIL_COND_V(!E, false);
+	return E->get().spawn;
+}
+
+void SceneReplicationConfig::property_set_spawn(const NodePath &p_path, bool p_enabled) {
+	List<ReplicationProperty>::Element *E = properties.find(p_path);
+	ERR_FAIL_COND(!E);
+	if (E->get().spawn == p_enabled) {
+		return;
+	}
+	E->get().spawn = p_enabled;
+	spawn_props.clear();
+	for (const ReplicationProperty &prop : properties) {
+		if (prop.spawn) {
+			spawn_props.push_back(p_path);
+		}
+	}
+}
+
+bool SceneReplicationConfig::property_get_sync(const NodePath &p_path) {
+	List<ReplicationProperty>::Element *E = properties.find(p_path);
+	ERR_FAIL_COND_V(!E, false);
+	return E->get().sync;
+}
+
+void SceneReplicationConfig::property_set_sync(const NodePath &p_path, bool p_enabled) {
+	List<ReplicationProperty>::Element *E = properties.find(p_path);
+	ERR_FAIL_COND(!E);
+	if (E->get().sync == p_enabled) {
+		return;
+	}
+	E->get().sync = p_enabled;
+	sync_props.clear();
+	for (const ReplicationProperty &prop : properties) {
+		if (prop.sync) {
+			sync_props.push_back(p_path);
+		}
+	}
+}
+
+void SceneReplicationConfig::_bind_methods() {
+	ClassDB::bind_method(D_METHOD("get_properties"), &SceneReplicationConfig::get_properties);
+	ClassDB::bind_method(D_METHOD("add_property", "path", "index"), &SceneReplicationConfig::add_property, DEFVAL(-1));
+	ClassDB::bind_method(D_METHOD("remove_property", "path"), &SceneReplicationConfig::remove_property);
+	ClassDB::bind_method(D_METHOD("property_get_index", "path"), &SceneReplicationConfig::property_get_index);
+	ClassDB::bind_method(D_METHOD("property_get_spawn", "path"), &SceneReplicationConfig::property_get_spawn);
+	ClassDB::bind_method(D_METHOD("property_set_spawn", "path", "enabled"), &SceneReplicationConfig::property_set_spawn);
+	ClassDB::bind_method(D_METHOD("property_get_sync", "path"), &SceneReplicationConfig::property_get_sync);
+	ClassDB::bind_method(D_METHOD("property_set_sync", "path", "enabled"), &SceneReplicationConfig::property_set_sync);
+}
diff --git a/scene/resources/scene_replication_config.h b/scene/resources/scene_replication_config.h
new file mode 100644
index 0000000000..b791be9414
--- /dev/null
+++ b/scene/resources/scene_replication_config.h
@@ -0,0 +1,90 @@
+/*************************************************************************/
+/*  scene_replication_config.h                                           */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#ifndef SCENE_REPLICATION_CONFIG_H
+#define SCENE_REPLICATION_CONFIG_H
+
+#include "core/io/resource.h"
+
+#include "core/variant/typed_array.h"
+
+class SceneReplicationConfig : public Resource {
+	GDCLASS(SceneReplicationConfig, Resource);
+	OBJ_SAVE_TYPE(SceneReplicationConfig);
+	RES_BASE_EXTENSION("repl");
+
+private:
+	struct ReplicationProperty {
+		NodePath name;
+		bool spawn = true;
+		bool sync = true;
+
+		bool operator==(const ReplicationProperty &p_to) {
+			return name == p_to.name;
+		}
+
+		ReplicationProperty() {}
+
+		ReplicationProperty(const NodePath &p_name) {
+			name = p_name;
+		}
+	};
+
+	List<ReplicationProperty> properties;
+	List<NodePath> spawn_props;
+	List<NodePath> sync_props;
+
+protected:
+	static void _bind_methods();
+
+	bool _set(const StringName &p_name, const Variant &p_value);
+	bool _get(const StringName &p_name, Variant &r_ret) const;
+	void _get_property_list(List<PropertyInfo> *p_list) const;
+
+public:
+	TypedArray<NodePath> get_properties() const;
+
+	void add_property(const NodePath &p_path, int p_index = -1);
+	void remove_property(const NodePath &p_path);
+
+	int property_get_index(const NodePath &p_path) const;
+	bool property_get_spawn(const NodePath &p_path);
+	void property_set_spawn(const NodePath &p_path, bool p_enabled);
+
+	bool property_get_sync(const NodePath &p_path);
+	void property_set_sync(const NodePath &p_path, bool p_enabled);
+
+	const List<NodePath> &get_spawn_properties() { return spawn_props; }
+	const List<NodePath> &get_sync_properties() { return sync_props; }
+
+	SceneReplicationConfig() {}
+};
+
+#endif // SCENE_REPLICATION_CONFIG_H