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Message Protocol

In Riker a single actor system has a defined message type, the protocol. The protocol can be a simple type such as String. A simple String protocol isn't useful in most real world applications where there might be several actors, each with its own specialized message type requirements.

Any Rust type can be used as the message protocol as long as it is Clone and Send. In addition, the Into trait must be implemented, specifically Into<ActorMsg>.


enum Protocol {
    CreateUser(String, String), // username, password
    UpdateUser(String), // password
    DeleteUser(String), // username

impl Into<ActorMsg<Protocol>> for Protocol {
    fn into(self) -> ActorMsg<Protocol> {

Here Into converts the protocol to the required ActorMsg::User variant.

To configure a Riker application to use your message type just set it in the model. If you're using the default Riker model from the riker-default crate you can use the following:

let model: DefaultModel<Protocol> = DefaultModel::new();

This provides a default model instance configured to use our Protocol enum.

If instead you are using a custom model you can see how to set your message protocol in Model & Customization.

Next you'll see how actors form a hierarchy.

Actor Hierarchy