fishbus

Tiny tiny library for receiving azure service bus messages

Install

dotnet add package fishbus

Note!

release v0.2.8 has a breaking change. Interface IHandleMessage was changed again. Handle should return HandlerResult to mark success, fail or abort If abort is returned from a handler the message will immediately be moved to Dead letter queue, and not retried.

release v0.2.7 has a breaking change. Interface IHandleMessage was changed. Handle no longer takes a delegate argument and it should return true/false to mark success or not

Declare a message type (an Event or a Command)

public class SomethingExcitingJustHappened
{
    public string Somedata { get; set; }
}

Write a handler for the message

public class DeleteUserHandler : IHandleMessage<SomethingExcitingJustHappened>
{
    public async Task<HandlerResult> Handle(SomethingExcitingJustHappened message)
    {
        Log.Information("Received SomethingExcitingJustHappened");
        return HandlerResult.Success();
    }
}

Configure the host for your handlers

Here we just have a console app, with a Program.cs, but this could just as well be a web app. We just need a host that can host a Microsoft.Extensions.Hosting.IHostedService implementation.

public static async Task<int> Main(string[] args)
{
    try
    {
        await new HostBuilder()
            .ConfigureHostConfiguration(configHost =>
            {
                configHost.SetBasePath(Directory.GetCurrentDirectory());
                configHost.AddEnvironmentVariables(prefix: "ASPNETCORE_");
            })
            .ConfigureServices((hostContext, services) =>
            {
                services
                    .ConfigureMessaging() //will register messagehandlers from current assembly
                    .Configure<MessageSources>(configuration.GetSection("MessageSources")); //register the MessageSources
            })
            .RunConsoleAsync();

        return 0;
    }
    catch (Exception ex)
    {
        Log.Fatal(ex, "Host terminated unexpectedly");
        return 1;
    }    
}

Configuration - appsettings.json

The following appsettings.json file could be used to configure the messagsources that the application will listen to

{
  "MessageSources": {
    "Subscriptions": [{
        "ConnectionString": "",
        "Name": "<name of topic>"
      }
    ],
    "Queues": [{
        "ConnectionString": ""
      }
    ]
  }  
}

Sending Messages

[MessageLabel("My.Message.Label")]
public class MyMessage
{
    public string A { get; set; }
    public string B { get; set; }
}

...

var publisher = new MessagePublisher(connectionString);

var myMessage = new MyMessage 
{
    A = "a",
    B = "b"
};

await publisher.SendAsync(myMessage);

Sending Message with custom Message Id

To leverage Azure Service Bus duplicate detection the MessageId should be set to an identifier based on your internal business logic. With Fishbus, Azure Service Bus MessageId logic can be overriden by adding the [MessageId] attribute to your custom message id property.

[MessageLabel("My.Message.With.Custom.MessageId")]
public class MyMessage
{
    [MessageId]
    public string MyId { get; set; }
    public string A { get; set; }
    public string B { get; set; }
}

...

var publisher = new MessagePublisher(connectionString);

var myMessage = new MyMessage 
{
    MyId = "id",
    A = "a",
    B = "b"
};

var duplicateMessage = new MyMessage
{
    MyId = "id",	
    A = "a",
    B = "b"
};

await publisher.SendAsync(myMessage);
await publisher.SendAsync(duplicateMessage); // Will be discarded by Azure Service Bus if duplicate detection activated and message sent within the duplicate detection history window.