Adhir, Im facing the same challenge using rules in a ETL process where performance is a main concern (some millisecs do the different when you have millions of executions), so I'm using Globals to keep data in the session. You can add a global object as a global variable in the session scope and all
the rules will have access to it in conditions and actions.
MyHelperClass helper = new MyHelperClass(); StatelessKnowledgeSession statelessSession = kb.newStatelessKnowledgeSession();
if (statelessSession == null){ log.error("Session was not created."); return; } statelessSession.setGlobal("myHelper", helper);
In the DRL you import the class and define the global. You can also define some static (or not) methods in the helper class to assit you and use them as functions in your rules (if used as functions, methods needs to be static, if no static, then they can be used as methods of the global instance in
the consequence block)
import com.mycompany.rules.helpers.MyHelperClass; import function com.mycompany.helpers.MyHelperClass.SOME_FUNCTION;
global com.emycompany.helpers.MyHelperClass helper;
This solution is not ideal, because you relay on java classes (code outside of the rules and RETE) to perform evaluations (functions with evals in conditions) and the consequence hide some code in java classes, which is not so good because one of the main features of a rule engine is the separation of the logic from the
static code... but it works and it helps sometimes.
I think I was not up to the point. Modifying facts re-executes the rules to maintain the truth. In my case, I want to pass the data between the rules and also do not want rules to execute again. I know if no-loop option is specified, it will not be re-executed however I do not want rule engine to even go & check for no-loop option (which is additional work).
I have written the rule DRL file having around 30 rules in
it. Some of the rules do intermediate calculation and those
calculation result is expected in the other rules in same DRL
file. I can do this by modifying the facts objects in one rule
and get the value in other rule. However, modifying the facts
object rebuild the RETE tree and affects the performance. Is
there any way by which I can pass the data across the rules in
same DRL file without rebuilding the RETE tree. (I am more
concerned about the performance)