For building reports you can convert business logic in any programming language. And use database data for generating reports. Against of business logic stored in database I place a high value on the power of expression, and I don’t find the SQL space to be all that expressive. Use the best tools you have on … Read more
It’s important to know that commands can be rejected after they are sent to the handler. At the very least, you could encounter a concurrency violation that cannot be detected until the aggregate root is touched. But also, the validation that can occur outside of the entity is simple validation. Not only string lengths, numeric … Read more
You should check out the Rules Design Pattern http://www.michael-whelan.net/rules-design-pattern/. It looks very similar to the example code you gave and consists of a base interface that defines a method for determining if a rule is satisfied and then various concrete implementations per different rules. As I understand it, your switch statement would turn into some … Read more
Implementing a simple rule-based evaluation system in Java isn’t that hard to achieve. Probably the parser for the expression is the most complicated stuff. The example code below uses a couple of patterns to achieve your desired functionality. A singleton pattern is used to store each available operation in a member map. The operation itself … Read more
What joekutner said + a recent 1hr Fosdem “introduction” video. Despite the comments, it’s actually really good, but what you have to have is the slides, so that you can follow through in a sane fashion. Here is a link to the Youtube-Video. It is fast, you’ll have to pause, but I found that I … Read more
Fist of all: I believe that you are mixing up the MVC pattern and n-tier-based design principles. Using an MVC approach does not mean that you shouldn’t layer your application. It might help if you see MVC more like an extension of the presentation layer. If you put non-presentation code inside the MVC pattern you … Read more