Starting up with NServiceBus

After many years with a inhouse made API on top of MSMQ, its time to evaluate other frameworks that gives us more out of the box.

NServiceBus looks like a great candidate.

• Easy install


• Extensible


• Strongly typed messages using generics


• Support for unit testing

The first problem was to use the StructureMap container in a strong name solution. The NServiceBus.ObjectBuilder.StructureMap262.dll extension have no stong name so I had to decompile and assemble it again with a keypair.

This is done using ildasm/ilasm.

sn -k test.snk

ildasm NServiceBus.ObjectBuilder.StructureMap262.dll /out=NServiceBus.ObjectBuilder.StructureMap262.il

ilasm NServiceBus.ObjectBuilder.StructureMap262.il /dll /key=test.snk /output=NServiceBus.ObjectBuilder.StructureMap262-sn.dll

Then its over to programming.

Message
We define a message with some properties that are sent from the client to the handler/server/service

    public class PingMessage : NServiceBus.IMessage
    {
        public string Text;
    }

Handler
Then a handler to consume these messages:

    public class PingMessageHandler : NServiceBus.IHandleMessages<PingMessage>
    {
        public ILog Logger = LogManager.GetLogger(typeof(PingMessageHandler));

        public void Handle(PingMessage message)
        {
            Logger.Debug(message.Text);
        }
    }

Unit testing
Normally I would have made Logger static readonly but we want to access this in our unit test

    [TestFixture]
    public class PingMessageHandlerFixture
    {
        [Test]
        public void SendMessage()
        {
            Test.Initialize(typeof(PingMessage).Assembly);
            var logger = A.Fake<log4net.ILog>();

            Test.Handler<PingMessageHandler>()
                .WithExternalDependencies(x => x.Logger = logger)
                .OnMessage<PingMessage>(x => x.Text = "hello world");

            A.CallTo(() => logger.Debug("hello world")).MustHaveHappened();
        }
    }

And the test goes green!

Great start :)

References:
www.nservicebus.com
fakeiteasy