Protocol

Overview

The Protocol module in this library is responsible for defining the communication protocol used to send messages between the client and server.

Key Concepts

It must be shared between client and server (usually a single ProtocolPlugin added to both apps), so that messages can be serialized and deserialized correctly. And it must be added after the ClientPlugins or ServerPlugins.

A protocol is composed of:

• Inputs: the client’s input type, i.e. the different actions a user can perform (move, jump, shoot, etc). Input handling is added with one of the input plugins, for example app.add_plugins(input::native::InputPlugin::<Inputs>::default()); (there are equivalents for leafwing inputs and bevy-enhanced-inputs).

• Messages: the messages exchanged between client and server. Any Send + Sync + 'static type works. You register one with:

  app.register_message::<Message1>()
      .add_direction(NetworkDirection::ServerToClient);

  The direction is only used to automatically add MessageReceiver<M>/MessageSender<M> on your Client/Sender entities, but you can also add these components manually.

• Components: the components that can be replicated from one World to the other. You register a component with:

  app.component::<PlayerId>()
      .replicate()
      .predict()
      .add_linear_interpolation();

  (You specify additional behaviour per component: prediction, interpolation, correction…)

• Channels: the delivery guarantees used to send messages. You register one with:

  app.add_channel::<Channel1>(ChannelSettings {
      mode: ChannelMode::OrderedReliable(ReliableSettings::default()),
      ..default()
  })
  .add_direction(NetworkDirection::ServerToClient);