Question

In drools, we often have common logic that needs to be invoked. There are two options to achieve this.

1. Use function in drools.
2. Move the common logic to some Util class in java and invoke it from drools.

Which of the above is recommended?

Thanks.

Answer 1

I always recommend using imported static methods unless it is a very simple piece of logic that is local to a subset of your rules and needs to be dynamically defined. The reasons are:

• keep DRL code clean of procedural logic, making maintenance cheaper and easier.
• it is easier to write an xUnit test to test your function logic in a static method than it is to test a DRL function.
• it makes the function available to all DRL files, without conflicts and without IDE error codes.

The DRL function construct is a facility to solve simple local problems, but java classes are where you want to keep and maintain your procedural code.