CODEWITHSUNDEEP
servicestack
Crixo
Crixo

Reputation: 3070

Pub/Sub using RabbitMQ

I'm trying to figure out how to implement pub/sub using ServiceStack MQ abstraction

Let's say I have a publisher app publishing a Hello request that will have n subscribers (different apps)

// Publisher
namespace Publisher
{
    public class RabbitPublisherAppHost : AppHostHttpListenerBase
    {
        public RabbitPublisherAppHost() : base("Rabbit Publisher Server", typeof(MainClass).Assembly) { }

        public override void Configure(Container container)
        {
            Routes
                 .Add<Publish>("/publish/{Text}");

            container.Register<IMessageService>(c => new RabbitMqServer());

            var mqServer = container.Resolve<IMessageService>();

            mqServer.Start();
        }
    }
}

namespace Publisher
{
    public class PublishService : Service
    {
        public IMessageService MessageService { get; set; }
        public void Any(Publish request)
        {
            PublishMessage(new Hello{Id=request.Text});
        }
    }
}

than I create the first subscriber

// Sub1
public class RabbitSubscriberAppHost : AppHostHttpListenerBase
{
    public RabbitSubscriberAppHost() : base("Rabbit Subscriber 1", typeof(MainClass).Assembly) { }

    public override void Configure(Container container)
    {
        container.Register<RabbitMqServer>(c => new RabbitMqServer());

        var mqServer = container.Resolve<RabbitMqServer>();

        mqServer.RegisterHandler<Hello>(ServiceController.ExecuteMessage, noOfThreads: 3);
        mqServer.Start();
    }
}

namespace Subscriber1
{
    public class HelloService : Service
    {
        public object Any(Hello req)
        {
            //..
        }
    }
}

Now If I create a similar app acting as the second subscriber, the 2 subscribers are sharing the same queue, so instead of the pub/sub a race condition is happening. In other word, what has to be done to implement a registration for each subscribers? I'd like all subscribers recevive the Hello request published, not just one of them according to a race condition.

Upvotes: 0

Views: 1041

Answers (1)

mythz
mythz

Reputation: 143339

ServiceStack's Messaging API follows the Services Request / Reply pattern (i.e. essentially using MQ instead of HTTP transport) and doesn't support Pub/Sub itself.

For RabbitMQ Pub/Sub you would have to implement it outside of the IMessaging API abstraction, e.g. publishing it to a Rabbit MQ topic from within your Service implementation.

Related ServiceStack does include a Pub/Sub library using Redis. Also depending on your use-case you may be able to make use of notifying multiple subscribers with Server Events .

Upvotes: 2

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