A few weeks ago, I decided I needed to play with the Unity Dependency Injection container. I wanted to see how Chris and the rest of the team had designed it and see how usable the container was. I had seen requests on the Web Client Software Factory project’s CodePlex site asking for a Unity version of WCSF. Put the two together, and I have a side project, a proof of concept I can legitimately do at work. My eventual end goal is to have the Order Management RI working with a new, Unity-based version of CWAB.
So, I sat down a few Saturdays ago, with CWAB, an early drop of Unity, and started working. After about eight hours I had the basics of CWAB working: there was a container, and a module loader, global services, and module level services. About 3 hours was used figuring out Unity, the differences between it and the container we created for CWAB (CompositionContainer) , and how to get around them. The rest was work, finding bugs in Unity (I filed a few the next day), and quite a lot of fun.
Since then, I have added a few more features, made some forwards progress, and lost ground after being overly optimistic about the impact of a few changes.
Now that I have learned a bit, I wanted to share the information with folks who might be interested in doing this themselves. Rather than trying to remember what I did the first time around, I am going to start over, take a different approach, document what I do as I go, and make a few posts out of this.
Please keep in mind, none of this is tested. Use at your own risk. No Support Available. Danger, Will Robinson! Danger!
This is a proof of concept that I am fairly certain will work, but I am not 100% certain. We will find out as we go. Oh, and I guarantee that there will be breaking changes.
My strategy will be to take the existing CWAB DLL and its unit tests, refactor the container behind an interface, modify the interface to nearly match Unity, and then drop Unity in replacing one implementation of the interface with another. After I get CWAB building and the unit tests passing with Unity, I will open up the code for the RI, replace references, and get it to work.
I will do all of this in an example-driven
test driven manner. I am sure I will cheat on occasion, but I will try to be honest and point it out when I do, as well as a reason why.
EDIT: Based upon feedback, I am making the source code available at CWAB and Unity.