Registration System

@Network Annotation

Placed on a package (in package-info.java), declares the protocol phase for network packets within that package.

@Network(protocol = PacketProtocol.PLAY)
package com.example.mod.network;

import dev.anvilcraft.lib.v2.network.register.Network;

Attribute	Type	Default	Description
protocol	PacketProtocol	PLAY	Protocol phase for the packets

PacketProtocol

public enum PacketProtocol {
    CONFIGURATION,  // Configuration phase (during login)
    PLAY,           // Game phase (default)
    COMMON          // Common phase
}

NetworkRegistrar

Provides the static method register(PayloadRegistrar, String modId), called inside RegisterPayloadHandlersEvent.

@SubscribeEvent
public static void register(final RegisterPayloadHandlersEvent event) {
    NetworkRegistrar.register(event.registrar("1"), "modid");
}

Registration Flow

1. Scans the mod files for @Network annotations to obtain target package names
2. Within each package, finds classes implementing IPacket (via interface information in ASM scan data)
3. Uses reflection to retrieve the static final Type<T> and static final StreamCodec<B, T> fields from each class
4. Automatically determines the direction based on implemented interfaces and calls the corresponding registration method

PacketData.find

Internal record class that extracts packet metadata via reflection:

record PacketData<B extends ByteBuf, T extends IPacket>(
    CustomPacketPayload.Type<T> type,
    StreamCodec<B, T> streamCodec,
    PacketDirection direction,
    IPayloadHandler<T> handler
)

Direction Detection Logic:

Implemented Interface	PacketDirection	Handler
IInsensitiveBiPacket	BIDIRECTIONAL	bidirectionalHandler
ISensitiveBiPacket	BIDIRECTIONAL	bidirectionalHandler
IClientboundPacket	CLIENTBOUND	clientHandler
IServerboundPacket	SERVERBOUND	serverHandler

Registration Method Mapping

protocol + direction -> registrar method

CONFIGURATION + CLIENTBOUND   -> configurationToClient()
CONFIGURATION + SERVERBOUND   -> configurationToServer()
CONFIGURATION + BIDIRECTIONAL -> configurationBidirectional()

PLAY + CLIENTBOUND   -> playToClient()
PLAY + SERVERBOUND   -> playToServer()
PLAY + BIDIRECTIONAL -> playBidirectional()

COMMON + CLIENTBOUND   -> commonToClient()
COMMON + SERVERBOUND   -> commonToServer()
COMMON + BIDIRECTIONAL -> commonBidirectional()

Troubleshooting

If registration throws an exception, check:

• Whether the packet class is missing a public static final Type<T> field
• Whether the packet class is missing a public static final StreamCodec<B, T> field
• Whether the packet implements the expected interface (IClientboundPacket / IServerboundPacket / bidirectional)
• Whether the @Network annotation is correctly placed on package-info.java