I was curious to see if I could generate a diagram that showed how all the services inside Tapestry 5 are interconnected. In the diagram, solid lines are dependencies, dashed lines are contributions, and dotted lines represent a services that listens to events from another service.
The final diagram is a bit complex. Ok, that's a tremendous understatement. Yellow nodes are public services, grey nodes are internal services, and orange nodes are simple beans (contributed into services) ... those beans, though, may still have their own dependencies. I think OmniGraffle choked on the complexity (why do some of the lines zip around so aimlessly?) and kind of "phoned it in" in terms of layout. I had hoped for something that could go on a T-shirt.
Worse yet, this is only a partial diagram; I didn't cover many of the dependencies that arrive as contributions to services (there's just a few of those in there). Those contributions would show up as even more orange nodes; these additional nodes would provide connections to many of the outliers that appear to be unreferenced.
Is this good or bad? Is it too complex? Can it be simplified? Does all that really need to be in there?
I think it is good: When I'm coding, I find it easy enough to work from a service interface, to the implementation of the interface, to the dependencies of the implementation. This works for me when developing Tapestry itself, or writing apps in Tapestry. Since there are so many small objects, no single object is large, or complex, or hard to understand or debug. It's a bit daunting to know where to start, I'm sure. However, only a few of these services are all that relevant for day-to-day development of Tapestry.
The moral of the story is that simplicity is hard! In Tapestry, pages and templates are as simple and straight forward as I think is possible. There's no excess, no distractions, no clutter, no boilerplate. Much of the logic represented in the diagram is to "fill around the edges" of this simplicity, to bridge the gap from the simple Tapestry component model to the much more complex world of stateless HTTP and multi-threaded request handling.
