Tuesday, December 27, 2011

NServiceBus Modeling Tools Review

After downloading and installing the package, the first thing that we have to do is create a new NSB application. So where is it? I expected it to be in a custom NServiceBus folder under Visual C#, but it wasn't. Then I tried Windows thinking that since we deploy as a Windows Service, it would be there. Nope. Modeling Projects? Nope. So then I did a search and found it at the Visual C# root. I eventually found it, but I'm hoping this moves somewhere more obvious. I'm also curious about the term "application". In the Advanced Distributed System Design course we talked at length on how an application is something that does not require network access, something like Microsoft Word. I'm thinking this should be changed to "System" instead.
It takes you right into the designer canvas which is nice. In the toolbox we have a pretty small set of items, a couple of message types, matching connectors, and two endpoints. I'm going to try to set up a simple send-only client that in turn publishes to a couple of subscribers.
Somehow my references are busted, so I opened the project to see the path and it's referencing some MSBuild variable, so I just updated all the refs. I'm not sure what the bug is here, but I'll blow right by it.
Now that we've generated the system, let's go and see what it did. So far the Client looks just fine:
All the message classes look fine and I'm glad to see that the commands are separated from the events into different assemblies. I'm also glad to see that the Publisher is defined correctly:
I didn't think it would do that based on the canvas. I would like to see a larger group of endpoints that are defined based on there role. This would include Publisher, Subscriber, Distributor, Worker, and Server. This would make it very obvious to the beginner what they are building. The Subscribers are also defined correctly:
It would also be nice if the endpoint configuration matched what was on the canvas, in this case that would be "AsA_Subscriber". Most people that I've helped to learn NSB get a little caught up on what the endpoints can do. If we added "AsA_Subscriber" we could also do some validation on the subscription itself(depending on the profile). All in all, this is a huge step forward. Congratulations to the team for significantly lowering the barrier to entry to getting started. I'd like to see some of the refinements I mentioned above and also would like some Distributor support(I'm sure that is on the list).

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