[rules-users] Question about drools-spring in a multi-treaded container (like tomcat).

[Gurvinder Narula1]

Hello all,

I've been reading up about drool-spring integration and have put together a simple project that wires together a KnowledgeBase and KnowledgeSession as follows :


<drools:resource id="GroupUnit" type="DRL"

source="file:/Users/drools/drools-spring-test/src/Rules/drls/GroupUnit.drl" />

<drools:resource id="GradeUnit" type="DRL"

source="file:/Users/drools/drools-spring-test/src/Rules/drls/GradeUnit.drl"" />

<drools:resource id="EvaluateUnit" type="DRL"

source="file:/Users/drools/drools-spring-test/src/Rules/drls/EvaluateUnit.drl"" />

<drools:grid-node id="node1" />

<drools:kbase id="kbase1" node="node1">

<drools:resources>

<drools:resource ref="GroupUnit" />

<drools:resource ref="GradeUnit" />

<drools:resource ref="EvaluateUnit" />

</drools:resources>

</drools:kbase>

<drools:ksession id="ksession" type="stateful" kbase="kbase1"

node="node1" />

Then in my Controller call, I 'AutoWire' in the StatefulKnowledgeSession as follows :


@Controller

@RequestMapping( value = "foo" )

final class FooController{



   @Autowired

   StatefulKnowledgeSession ksession;



   @RequestMapping(  method = RequestMethod.GET )

   @ResponseBody

   public String evaluateUnit() {



Unit unit = new Unit("030", "502", "C", "9484", "45", new String[] {},

null);



  if (ksession != null) {

  ksession.fireAllRules();

  ksession.insert(unit);

  ksession.fireAllRules();

  return "<UnitCategory>" + unit.getUnitCategory() + "</UnitCategory>";

  }

  else

  return "<message> stateful session is null</message>";

   }


The main question that I have is that – is this solution thread-safe ? From what I understand of spring is that beans configured without any additional qualifiers are inherently singletons. And when deployed in a multi-theaded container like tomcat, Spring assumes that the beans being severed up a thread-safe. So from I have read is that KnowledeSessions are inherently not thread safe. So putting the 2 together, I leaning towards the assessment that this above solution is NOT thread safe and that if I do want it to be thread safe I should set the StatefulKnowledgeSession to 'prototype' and not leave it as a singleton.

Please let me know if I'm missing anything in my assessment here !

Thanks in advance,
Gurvinder




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