I'm new to ODM 8.12, would like to know how I can do the rule logging in ODM 8.12. For using EngineObserver, do I need to create engine? Can I not access the existing one and get the rule instances to do some logging for rule execution start , end etc.Thanks!

Hi,

You do not need to create the engine you can use a reference in a b2x code:

if (com.ibm.rules.engine.runtime.RunningEngineWithWorkingMemory.this instanceof com.ibm.rules.engine.ruleflow.runtime.RunningRuleflowEngine) {
    com.ibm.rules.engine.ruleflow.runtime.RunningRuleflowEngine engine = (com.ibm.rules.engine.ruleflow.runtime.RunningRuleflowEngine)com.ibm.rules.engine.runtime.RunningEngineWithWorkingMemory.this;
    engine.addObserver(myobserver);

You will find a full sample of integration  in the Decisions Developer repository on github: https://github.com/DecisionsDev/decision-engine-observer-sample