Protocol

Overview

The Protocol module in this library is responsible for defining the communication protocol used to send messages between the client and server. The Protocol must be shared between client and server, so that the messages can be serialized and deserialized correctly.

Key Concepts

Protocol Trait

A Protocol contains multiple sub-parts:

• Input: Defines the user inputs, which is an enum of all the inputs that the client can send to the server. Input handling can be added by adding the InputPlugin plugin: app.add_plugins(InputPlugin::<I>::default());

• LeafwingInput: (only if the feature leafwing is enabled) Defines the leafwing ActionState that the client can send to the server. Input handling can be added by adding the LeafwingInputPlugin plugin: app.add_plugins(LeafwingInputPlugin::<I>::default());

• MessageRegistry: Will hold metadata about the all the messages that can be sent over the network. Each message must be Serializable + Deserializeable + Clone. You can register a message with the command app.add_message::<Message1>(ChannelDirection::Bidirectional);

• Components: Defines the component protocol, which is an enum of all the components that can be replicated between the client and server. Each component must be Serializable + Clone + Component. You can register a component with:

  app.register_component::<PlayerId>(ChannelDirection::ServerToClient)
    .add_prediction::<PlayerId>(ComponentSyncMode::Once)
    .add_interpolation::<PlayerId>(ComponentSyncMode::Once);

  (You can specify additional behaviour for the component, such as prediction or interpolation.)

• Channels: the protocol should also contain a list of channels to be used to send messages. A Channel defines guarantees about how the packets will be sent over the network: reliably? in-order? etc. You can register a channel with:

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