ProSol.Messaging 4.0.0-rc.1

ProSol.Messaging

Implements a message broker with ability to build a pipeline of listeners.

API

The project contains an API for the Observer pattern: IPublisher, ISubscriber, and PipelinePublisher.

• The IPublisher interface is aimed to provide a layer of absctraction to the client.
• The ISubscriber interface decalres a subscription contract with chained calls support via NextDelegate.
  • NextDelegate: is a mandatory delegate to trigger if current subscriber wants to bypass a message to next subscriber.
• PipelinePublisher: a ready-to-use implementation for chained subscriptions.

Demo

Let's see how works in a console app, by making a publisher for strings, which addresses the message to the StringListener, but there is a StringLimitListener between them.

So, the StringLimitListener will drop the message longer than "Please" string:

using ProSol.Messaging;

var maxLength = "Please".Length + 1;

var broker = new MessageBroker<string>();
// Set up a chain.
broker.Subscribe(new StringLimitListener(maxLength));
broker.Subscribe(new StringListener());

// Push some messages.
broker.Publish("Please");
broker.Publish("STOP");
broker.Publish("The planet");
// OUTPUT:
// Please
// STOP

// Clean up.
broker.Complete();

public class StringListener : ISubscriber<string>
{
    public void OnCompleted() { }

    public void OnNext(string message, NextDelegate next)
    {
        Console.WriteLine(message);

        if (message != "STOP")
        {
            next();
        }
    }
}

public class StringLimitListener(int limit) : ISubscriber<string>
{
    private readonly int limit = limit;

    public void OnCompleted() { }

    public void OnNext(string message, NextDelegate next)
    {
        if (message.Length < limit)
        {
            next();
        }
    }
}