MassTransit and Ninject

Distributed Systems, MassTransit

My DI container of choice is Ninject. The reasons aren’t overly important, other than I hate, hate, hate XML. If I wanted to program in XML, I’d use Java. Fortunately, there are DI containers in the .Net space that don’t require all that XML, and Ninject is one of them. The Ninja connections kinda bug me, but I actually had it in my head as NINject first, so Trent trumps stupid martial arts posing.

The first thing I came across while trying to get into MassTransit, though, is that Ninject support, while advertised as existing, is a little lacking. It could just be me, but I found a problem with using any of the non-default constructors in MassTransitModuleBase, which is derived from NinjectModule. NinjectModule is the base class from which you derive to set up your bindings, and then your derived class is passed into a Ninject Kernel, which does the binding resolution. Ninject isn’t really ready to set up bindings until the Load() override in your derived class is called, but MassTransitModuleBase tries to set up bindings in the non-default constructors using the values that are passed in.

This makes sense, because the other significant non-XML based DI container, StructureMap, appears to allow this, and clearly the MassTransit guys have used that container and used it as the model for the Ninject support. Dru Sellers, one of the original authors, told me in a tweet that they weren’t all that familiar with Ninject. Its understandable – how many DI containers do you really need to know how to use?

So, I had managed to make it work by not using any of the non-default constructors at this point, because I assumed that the MassTransit implementation was correct. The result looked something like this (note that I used Mike Hadlow’s first look article as the basis for my code):

[Gist MassTransit and Ninject Example 1.cs]

   public class PlayMassTransitModule : MassTransitModuleBase

   {

       public override void Load()

       {

           base.Load();

 

           RegisterEndpointFactory(x =>

           {

               x.RegisterTransport<LoopbackEndpoint>();

               x.RegisterTransport<MulticastUdpEndpoint>();

               x.RegisterTransport<MsmqEndpoint>();

           });

 

           RegisterServiceBus(@"msmq://localhost/mt_mike_publisher", x =>

           {

               x.SetConcurrentConsumerLimit(1);

 

               ConfigureSubscriptionClient(@"msmq://localhost/mt_subscriptions", x);

           });

       }

   }

Notice that I had to set everything up in the Load() override. This is the way it has to be right now. I’m working on a patch so that you can use the Ninject container integration exactly like you do with StructureMap. Hopefully I’ll have it done and accepted by the time this post is published. In the meantime, if you want to see the full solution, check out this branch in my github DemoCode space: https://github.com/ekepes/DemoCode/tree/NinjectDemo

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Getting on the Bus

Distributed Systems, MassTransit

The kinda, sorta message broker we’ve built at work over the last few years works just fine for what we are doing today. I’m actually rather proud of some of the things we’ve done with it. But the primitive pub/sub implementation I bolted on it isn’t going to do the trick going forward, as we want to have distinct services for different functional concerns. We also want to be able to use CQRS where is makes sense, but at the very least operate in an event driven manner. The current code base won’t allow that to work without a lot of change.

The world has changed since we started on the project. There are at least two solid ESB projects out there for .Net (a third depending upon what you think of the state of Ayende’s Rhino Service Bus, but I don’t think it would be responsible to depend upon a single maintainer project for something so business critical). NServiceBus is the gold standard, and rightly so – Udi Dahan is the go-to guy for all things distributed in the .Net space (and beyond). MassTransit is also a very viable project.

The problem with NServiceBus for me, at this time, is that I can’t risk having the load on the system exceed the free community version. We have entirely too many customers, and our products are sold as an on-premise solutions. We could build in the cost, no doubt, but at the moment that’s not attractive. Especially since MassTransit is proving to be just what we need. So, I’m going forward with heavily evaluating MassTransit and figuring out how to make it work for us.

One of the biggest problems with MassTransit is an absolute dearth of documentation. Some of the samples are even out of date. This seems like a good place for someone to help out, and I’ve wanted to help out on an OSS project for a long time, but couldn’t find my niche. It seems like trying to help with the documentation problem is a good use of my time, and hopefully will help me better understand how MassTransit works. So, we interrupt our previously scheduled exploration of Ruby and Rails to bring you this series on MassTransit.