Sending & Receiving

With a payload defined, use dev.architectury.networking.NetworkManager to register a receiver and send it. Packets travel in one of two directions, given by NetworkManager.Side:

• C2S - client to server.
• S2C - server to client.

Client → Server (C2S)

Register the receiver on the server, then send from the client.

// Server-side registration (your common initializer is fine):
NetworkManager.registerReceiver(NetworkManager.Side.C2S,
    OpenGuiPayload.TYPE, OpenGuiPayload.CODEC,
    (payload, context) -> {
        ServerPlayer player = (ServerPlayer) context.getPlayer();
        context.queue(() -> {
            // safe to touch game state here - see the threading note below
        });
    });

// Client-side: send it
NetworkManager.sendToServer(new OpenGuiPayload(pos));

Server → Client (S2C)

Declare the payload type on the server, register the receiver on the client, then send from the server.

// Server-side: declare the type
NetworkManager.registerS2CPayloadType(SyncStatsPayload.TYPE, SyncStatsPayload.CODEC);

// Client-side: register the receiver
NetworkManager.registerReceiver(NetworkManager.Side.S2C,
    SyncStatsPayload.TYPE, SyncStatsPayload.CODEC,
    (payload, context) -> context.queue(() -> {
        // update client-side state
    }));

// Server-side: send to one or many players
NetworkManager.sendToPlayer(serverPlayer, new SyncStatsPayload(10, 4.5f));
NetworkManager.sendToPlayers(serverLevel.players(), new SyncStatsPayload(10, 4.5f));

The receiver and its context

A receiver is a NetworkManager.NetworkReceiver<T> - (payload, context). The PacketContext gives you:

Member	Description
getPlayer()	The player on this side (the sender on the server; the local player on the client).
queue(Runnable)	Run something on the main game thread.
getEnvironment()	Env.CLIENT or Env.SERVER.
registryAccess()	The RegistryAccess for this side.

Run game logic on the main thread

Receivers are invoked on the network thread. Reading the payload is fine there, but anything that touches world or game state must be wrapped in context.queue(() -> ...) so it runs on the main thread.

Checking whether the other side can receive

Before sending, you can check that the recipient has your packet registered (for example, a vanilla client connecting to your server):

if (NetworkManager.canPlayerReceive(player, SyncStatsPayload.TYPE)) {
    NetworkManager.sendToPlayer(player, new SyncStatsPayload(10, 4.5f));
}

// And from the client, before a C2S send:
if (NetworkManager.canServerReceive(OpenGuiPayload.TYPE)) {
    NetworkManager.sendToServer(new OpenGuiPayload(pos));
}

Converting to a vanilla packet

NetworkManager.toPacket(side, payload, registryAccess) builds a vanilla Packet from your payload (and toPackets(...) returns a list when transformers split it). This is useful when an API expects a raw Packet - for instance, custom entity spawning, covered in Entity Spawn Packets.