Crochet

Crochet is a simple Fabric library mod which provides Networking & Entity Data tools for other mods to use. By itself, it includes no ingame content.

Crochet Packets

Creating an sending packets with Crochet is easy! Simply implement IPacket on your packet class, and create a Handler class which extends MessageHandler<YourPacketClass. A simple packet which sends an integer could look like this.

public class DemoPacket implements IPacket
{
    public static final Identifier ID = new Identifier("example_mod", "demo");
    private int number;
    
    private DemoPacket() { }
    
    public DemoPacket(int number)
    {
        this.number = number;
    }
    
    @Override
    public void read(PacketByteBuf buf)
    {
        number = buf.readInt();
    }
    
    @Override
    public void write(PacketByteBuf buf)
    {
        buf.writeInt(number);
    }
    
    @Override
    public Identifier getID()
    {
        return ID;
    }
    
    public static class Handler extends MessageHandler<DemoPacket>
    {
        @Override
        protected DemoPacket create()
        {
            return new DemoPacket();
        }
    
        @Override
        public void handle(PacketContext ctx, DemoPacket message)
        {
            System.out.println("The number is " + message.number);
        }
    }
}

You need to register the packet on the side which will be receiving it. Client-bound packets should be registered in ClientModInitializer#onInitializeClient while server-bound packets can be registered in ModInitializer#onInitialize. See the example below for an example of packet registration.

// For Client-Bound Packets
ClientSidePacketRegistry.INSTANCE.register(DemoPacket.ID, new DemoPacket.Handler());

// For Server-Bound Packets
ServerSidePacketRegistry.INSTANCE.register(DemoPacket.ID, new DemoPacket.Handler());

Crochet Entity-Data

Crochet also provides tools that allow mod developers to store persistent data on players. Data is stored in CompoundTag and sent to the client whenever it is marked as dirty. Therefore, data should be added on the server-side, although adding it on both sides will also work. Below is a simple example of the Crochet PlayerData system being used to store a boolean. Not that "example_mod" should be replaced by your mod ID in order to prevent data conflicts between mods.

public boolean onActivated(PlayerEntity player)
{
    PlayerData.get(player, "example_mod").putBoolean("UsingItem", true);
    PlayerData.markDirty(player);
}