I have a project whose core domain is dramatically changing. It's possible to use 50% of the core functionality from this site and just add the 50% new functionality, but I am starting to consider that maybe it might be faster to simply redo the product in Rails. Development speed is very important.
There are some things I really like about java - the performance and scalability are very good. I am not a crappy Java developer, so my apps tend to run very well - better than the Rails sites I've seen. I've always accepted the idea that people probably just throw a little more money at the problem when it comes to using Rails, which probably works itself out in the end because of the insane productivity benefits.
I am actually quite agile with Java. I know it will still take me longer to add a basic entity to the system, but I am quick at it and I don't mind it that much. At least it's easy and straight-forward to do.
What I do mind is:
- having to start/stop the server just to fix a route, lazy load exception, controller is going to wrong view, etc.
- putting up with the fact that unit/integration tests sometimes have different results than the production environment (because annotations on controllers can't be tested, or lazy-loading exceptions occur during asynchronous service calls, or things like that). Knowing if your Jackson is marshaling your data properly is another Tomcat-only thing because it's handled by Spring. There are lots of things that go wrong after you have tested all that you can, and this frankly annoys the crap out of me.
- putting up with the occasional maven/classloader problem that doesn't rear its ugly head until you deploy into tomcat. It gives the false impression that everything is "a-okay" when you are in your IDE.
- having to put more effort to do database migrations than the ruby people ever have to.
- putting up with framework bugs in Spring that block (it's happened ab