Crate actix_broker

A message broker for the Actix actor framework.

The actix_broker crate contains SystemService and ArbiterService Brokers that keep track of active subscriptions to different Messages. Broker services are automatically started when an actor uses functions from the BrokerSubscribe and BrokerIssue traits to either subscribe to or issue a message.

Examples

use actix::prelude::*;
use actix_broker::{BrokerSubscribe, BrokerIssue, SystemBroker, ArbiterBroker, Broker};

// Note: The message must implement 'Clone'
#[derive(Clone, Message)]
#[rtype(result = "()")]
struct MessageOne;

#[derive(Clone, Message)]
#[rtype(result = "()")]
struct MessageTwo;

#[derive(Clone, Message)]
#[rtype(result = "()")]
struct MessageThree;

struct ActorOne;

impl Actor for ActorOne {
    // Note: The actor context must be Asynchronous,
    // i.e. it cannot be 'SyncContext'
    type Context = Context<Self>;

    fn started(&mut self,ctx: &mut Self::Context) {
        // Asynchronously subscribe to a message on the system (global) broker
        self.subscribe_system_async::<MessageOne>(ctx);
        // Asynchronously issue a message to any subscribers on the system (global) broker
        self.issue_system_async(MessageOne);
        // Synchronously subscribe to a message on the arbiter (local) broker
        self.subscribe_arbiter_sync::<MessageTwo>(ctx);
        // Synchronously issue a message to any subscribers on the arbiter (local) broker
        self.issue_arbiter_sync(MessageTwo, ctx);
    }
}
     
    // To subscribe to a messsage, the actor must handle it
impl Handler<MessageOne> for ActorOne {
    type Result = ();

    fn handle(&mut self, msg: MessageOne, ctx: &mut Self::Context) {
        // An actor does not have to handle a message to just issue it
        self.issue_async::<SystemBroker, _>(MessageThree);
    }
}

// Messages can also be sent from outside actors
fn my_function() {
    Broker::<SystemBroker>::issue_async(MessageOne);
}

Structs

ArbiterBroker

Broker

SystemBroker

Traits

BrokerIssue

The BrokerIssue provides functions to issue messages to subscribers.

BrokerMsg

BrokerSubscribe

The BrokerSubscribe trait has functions to register an actor’s interest in different messages.