Rebus is a lean service bus implementation, similar in nature to NServiceBus and MassTransit.

In fact, its goal is to copy NServiceBus in almost every aspect, only deviating by having

• a simpler and more intuitive configuration story
• not quite as many options
• no doodleware
• dependencies only on .NET 4 BCL and Log4net
• much better error messages
• a frictionless getting-up-and-running-experience

Oh, and Rebus is free as in beer and speech.

I am a happy NServiceBus user, and I still am. It just puzzles me that

• NServiceBus is 60 KLOC spread across 200+ projects - the code is hard to read
• NServiceBus went from being absolutely free to be licensed

I realize that NServiceBus is pretty cheap when you think of all the good things it can do for you, but to many people I think the license fee is an annoyance that will hinder them in introducing NServiceBus in all of their awesome projects - Which is a shame!

Then why don't I just use MassTransit then? Well, I wanted to do that, but I had so much trouble figuring out the philosophy of the MassTransit project that I gave up learning how to use it. I don't like how it needs a central runtime service to manage subscriptions, and I had a hard time figuring out how to make it work. And then there's the option of using PGM over MSMQ, but it just didn't work how I wanted it to work. Long story short: Too hard to get started!

More info coming soon at http://mookid.dk/oncode/rebus

One day, maybe I'll tweet something as well... @mookid8000

Pretty clunky at the moment, I'm sorry... haven't gotten into the configuration API story yet. Right now, this is how you get going with Rebus:

First, decide how you want to ISendMessages and IReceiveMessages - Rebus has something that can do both: MsmqMessageQueue - therefore:

var msmq = new MsmqMessageQueue(@".\private$\service_input_queue");

Then, decide how subscriptions are to be stored if the service is a publisher - right now, there's InMemorySubscriptionStorage and SqlServerSubscriptionStorage to choose from. Let's be serious about this:

var connectionString = "data source=.;initial catalog=rebus_subscriptions;integrated security=sspi";
var subscriptionStorage = new SqlServerSubscriptionStorage(connectionString);

Now, figure out how to go from TMessage to instances of something that implements IHandleMessages<TMessage>. This is where you'd probably insert your favorite IoC container. Let's pretend that I implemented IActivateHandlers in a CastleWindsorHandlerActivator (it's only two methods) - that would allow me to do this:

var container = GetWindsorContainerFromSomewhere();
var handlerActivator = new CastleWindsorHandlerActivator(container);

Now, figure out how a given message type should be mapped to the name of the endpoint that owns that message type - you do that by implementing IDetermineDestination (it's one single method that maps from Type to string) - let's pretend I implemented that by looking up some endpoint mappings in the app.config of my current process:

var endpointMapper = new AppConfigBasedEndpointMapper();

Lastly, figure out how to ISerializeMessages - at the moment there's only JsonMessageSerializer:

var serializer = new JsonMessageSerializer();

and NOW we're ready to create the bus:

var bus = new RebusBus(handlerActivator, msmq, msmq, subscriptionStorage, endpointMapper, serializer).Start();

If you've used NServiceBus, lots of things will immediately make sense with Rebus - everything about sending, publishing, subscribing, etc is the same.

Well, that was a teaser. More stuff coming up some time in the future.

Rebus is Beer-ware.