In my project I have some requirements I want to use Drools to fit. There are some rules that do not change often and serve as the foundation. Then there should be a second DSLR which changes more often and in which the already defined rules should be expanded, overriden and/or aggregated.
Is it possible to use drools for such requirements. I red the Drools documentation but I am not sure that this is possible.
I suspect you have made your plans by now, but for reference, here's something of an answer.
What you describe is a typical Drools application, so at a high level, 'yes' Drools can be used that way.
You can set up some initial DRL technical rules, which are very much for developers to maintain. The next step is how to support the business users. Drools provides:
DSL/DSRL - Developers write DSL templates, which map a natural language style of phrase to DRL. Business users write DSRL in that natural language syntax. In reality I tend to find that this is easy to read, but not so easy to write correctly. However, if you have Guvnor, the guided rules make use of the DSL to enable business users to build up rules easily. They can just pick and choose from drop-down lists to build rules using the DSL.
Spreadsheets - Here the developers create a spreadsheet with a number of hidden fields that map the cells to rules. Each row in the table becomes a rule. A business user just needs to fill in fields.
Web decision tables - In Guvnor, these are similar to spreadsheets in look, a developer can easily create a table which maps LHS constraints to actions, which could be modifying existing facts, or creating new ones. Again, business users can maintain these by adding rows to the tables and changing values in the cells. These are probably the least 'technical' from a business user's perspective, so I prefer them where possible.
If you use Guvnor, then the business users have a web site they go to where they can update rules and save them. Depending on how you want to work, the runtime rules engine can automatically pick up those changes, or you can implement a more strict release procedure for rules changes.
