[rules-users] Drools - is dynamic change possible ?

[pns77]

Any suggestions / guidance for the below question ?


pns77 wrote:
> 
> Hi,
> 
> The following is the block of code that i tried
> 
>             RuleBase ruleBase = readRule();
>             WorkingMemory workingMemory =
> ruleBase.newStatefulSession(false); // to keep reference
>             // Create a message object
>             workingMemory.insert( message );
>             workingMemory.fireAllRules();
> 
> When i try chaning the "drl" file at run time the change doesnt get
> reflected. Is there anything else i need to be doing here?  Any additional
> jar files ?
> 
> To have this change take effect at runtime - do i need to create a new
> session for each run or do i need to retain the session - i tried both
> "newStatefulSession(false)" and "newStatefulSession()" - get the same
> result with both.
> 
> Just to add on...for two successive runs, the times taken to create
> RuleBase object were
> 
> <<<<<<<< START >>>>>>>>>>1187339950422
> <<<<<<<<<< FINISH >>>>>>>>>>>>>>>>.1187339956100 => ~ 6 seconds
> 
> <<<<<<<< START >>>>>>>>>>1187340049090
> <<<<<<<<<< FINISH >>>>>>>>>>>>>>>>.1187340049721 => ~ .6 seconds
> 
> Doesnt this mean that there is a cache that prevents the modified drl file
> from being parsed ?
> 
> 
> Mark Proctor wrote:
>> 
>> Yes this can be done at runtime. The RuleBase has a reference to each of 
>> the created StatefulSessions that has not called dispose() yet and will 
>> push those rule changes out to each running session.
>> 
>> 
>> Mark
>> pns77 wrote:
>>> Thanks for the response.
>>>
>>> Just to confirm when you say "...but you can remove a rule and add
>>> another
>>> in its place..." - can this be done at runtime - i.e server is running,
>>> i go
>>> add a new rule/change the output of an existing rule. If so, can  i have
>>> the
>>> new rule take effect ?
>>>
>>> Also, do i need to include any specific jar file for this dynamic
>>> feature ?
>>>
>>> Am not looking at performance here - more from a
>>> maintenance/changeability
>>> point of view.
>>>
>>>
>>> Mark Proctor wrote:
>>>   
>>>> you cannot change an individual rule, but you can remove a rule and add 
>>>> another in its place.
>>>>
>>>> Mark
>>>> pns77 wrote:
>>>>     
>>>>> Have been able to execute/run a sample Drools file
>>>>>
>>>>> import com.sample.Message;
>>>>>  
>>>>> rule "Hello World"
>>>>>     when
>>>>>         m : Message( status == Message.HELLO, message : message,
>>>>> testStringExternal : testStringExternal )
>>>>>     then
>>>>>         System.out.println( message );
>>>>>         m.setMessage( "Goodbye cruel world" );
>>>>>         System.out.println( testStringExternal + "Message.HELLO" );
>>>>>         m.setStatus( Message.GOODBYE );
>>>>>         update( m );
>>>>> end
>>>>>
>>>>> Now, is it possible to change the logic dynamically at runtime ? Or is
>>>>> the
>>>>> drl file used only to externalize the business logic? I tried changing
>>>>> the
>>>>> message in drl file and it didnt get reflected
>>>>>
>>>>> Environment - RAD 6.0/jdk 1.4
>>>>>
>>>>> Used the following set of jar files
>>>>> C:\Drools\libraries\drools-core.jar;
>>>>> C:\Drools\libraries\drools-compiler.jar;
>>>>> C:\Drools\libraries\mvel14.jar;
>>>>> C:\Drools\libraries\antlr-runtime.jar;
>>>>> C:\Drools\libraries\xstream.jar;
>>>>> C:\Drools\lib\core-3.2.3.v_686_R32x.jar; 
>>>>>   
>>>>>       
>>>> _______________________________________________
>>>> rules-users mailing list
>>>> rules-users at lists.jboss.org
>>>> https://lists.jboss.org/mailman/listinfo/rules-users
>>>>
>>>>
>>>>     
>>>
>>>   
>> 
>> 
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>> 
>> 
> 
> 

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