MetroBus

---

Lightweight messaging wrapper of MassTransit

NuGet Packages

> dotnet add package MetroBus
> dotnet add package MetroBus.Autofac
> dotnet add package MetroBus.Microsoft.Extensions.DependencyInjection

Supports:

• .NET Standard 2.0

Features:

• Currently only supports RabbitMQ transport
• Provides easy way to create Producer and Consumer for Pub/Sub
• Provides easy way to handle Request/Response conversations
• Provides message scheduling
• Includes optional incremental auto retry policy
• Includes optional circuit breaker
• Includes optional rate limiter
• Autofac support
• Microsoft.Extensions.DependencyInjection support

Usage:

Initializing bus instance for Producer:

// For events
IBusControl bus = MetroBusInitializer.Instance.UseRabbitMq(rabbitMqUri, rabbitMqUserName, rabbitMqPassword)
					.InitializeEventProducer();

// For commands
ISendEndpoint bus = MetroBusInitializer.Instance.UseRabbitMq(rabbitMqUri, rabbitMqUserName, rabbitMqPassword)
                    .InitializeCommandProducer(queueName);

after bus instance initializing then you can use Send or Publish methods.

// For events
await bus.Publish<TEvent>(new
{
    SomeProperty = SomeValue
}));

// For commands
await bus.Send<TCommand>(new
{
    SomeProperty = SomeValue
}));

using Consumer:

static void Main(string[] args)
{
	IBusControl bus = MetroBusInitializer.Instance
                        .UseRabbitMq(string rabbitMqUri, string rabbitMqUserName, string rabbitMqPassword)
                        .RegisterConsumer<TCommandConsumer>(string queueName)
                        .RegisterConsumer<TEventConsumer>(string queueName)
                        .Build();

	bus.Start();

	//if you want to stop
	bus.Stop();

	Console.ReadLine();
}

TCommandConsumer could like below:

public class TCommandConsumer : IConsumer<TCommand>
{
    public async Task Consume(ConsumeContext<TCommand> context)
    {
        var command = context.Message;

		//do something...
        await Console.Out.WriteAsync($"{command.SomeProperty}");
    }
}

Initializing bus instance for Request/Response conversation:

IRequestClient<TRequest, TResponse> client = MetroBusInitializer.Instance.UseRabbitMq(string rabbitMqUri, string rabbitMqUserName, string rabbitMqPassword)
                                                                    .InitializeRequestClient<TRequest, TResponse>(string queueName);

TResponse result = await client.Request(new TRequest
{
    Command = "Say hello!"
});

and consumer for Request/Response conversation could like below:

public class TCommandConsumer : IConsumer<TRequest>
{
    public async Task Consume(ConsumeContext<TRequest> context)
    {
        var command = context.Message;

		//do something...
        await Console.Out.WriteAsync($"{command.SomeProperty}");

		//and
		context.Respond(new TRequest
            {
                Command = "Hello!"
            });
    }
}

using Consumer with Microsoft.Extensions.DependencyInjection:

new HostBuilder ()
    .ConfigureServices ((hostContext, services) =>
    {
        services.AddMetroBus (x =>
        {
            x.AddConsumer<TCommandConsumer>();
            x.AddConsumer<TEventConsumer>();
        });

        services.AddSingleton<IBusControl> (provider => MetroBusInitializer.Instance
                .UseRabbitMq (string rabbitMqUri, string rabbitMqUserName, string rabbitMqPassword)
                .RegisterConsumer<TCommandConsumer>("foo.command.queue", provider)
                .RegisterConsumer<TEventConsumer>("foo.event.queue", provider)
                .Build ())
            .BuildServiceProvider ();

        services.AddHostedService<BusService> ();
    })
    .RunConsoleAsync ().Wait ();


public class BusService : IHostedService
{
    private readonly IBusControl _busControl;

    public BusService(IBusControl busControl)
    {
        _busControl = busControl;
    }

    public Task StartAsync(CancellationToken cancellationToken)
    {
        return _busControl.StartAsync(cancellationToken);
    }

    public Task StopAsync(CancellationToken cancellationToken)
    {
        return _busControl.StopAsync(cancellationToken);
    }
}

PS: Publisher and Consumer services must be used same TCommand or TEvent interfaces. This is important for MassTransit integration. Also one other thing is rabbitMqUri parameter must start with "rabbitmq://" prefix.

There are several options you can set via fluent interface:

• .UseRetryPolicy().UseIncrementalRetryPolicy(int retryLimit, TimeSpan? initialIntervalTime, TimeSpan? intervalIncrementTime, params Exception[] retryOnSpecificExceptionType).Then()
• .UseCircuitBreaker(int tripThreshold, int activeThreshold, TimeSpan? resetInterval)
• .UseRateLimiter(int rateLimit, TimeSpan? interval)
• .UseMessageScheduler()
• .UseDelayedExchangeMessageScheduler()
• .UseConcurrentConsumerLimit(int concurrencyLimit)