[rules-users] Strange exit in RuleFlow

[Kris Verlaenen]

Femke,

The reason is that the Drools engine by default is a passive component,
meaning that it will only execute if you tell it to explicitly (e.g.
using fireAllRules()).  In this case, if you use a small timer the
engine is still executing startProcess() and hence the timer will be
executed.  When using a larger timer delay, the timer will trigger but
will only put an action on the action queue.  If you would call
fireAllRules after one minute, all queued actions (in this case the
execution of the timer) will be executed.  You can however also
configure the Drools engine to fire continuously using fireUntilHalt().
 I just added this new section in the documentation to explain it:

By default, the Drools engine is a passive component, meaning that it
will only start processing if you tell it to (for example, you first
insert the necessary data and then tell the engine to start processing).
In passive mode, a timer that has been triggered will be put on the
action queue. This means that it will be executed the next time the
engine is told to start executing by the user (using fireAllRules() or
if the engine is already / still running), in which case the timer will
be executed automatically.

When using timers, it does usually make sense to make the Drools engine
an active component, meaning that it will execute actions whenever they
become available (and not wait until the user tells it to start
executing again). This would mean a timer would be executed once it is
triggered. To make the engine fire all actions continuously, you must
call the fireUntilHalt() method. That means the engine will continue
firing until the engine is halted. The following fragment shows how to
do this (note that you should call fireUntilHalt() in a separate thread
as it will only return if the engine has been halted (by either the user
or some logic calling halt() on the session):

new Thread(new Runnable() {
  public void run() {
    ksession.fireUntilHalt();
  }
}).start();

// starting a new process instance
ksession.startProcess("...");
// any timer that will trigger will now be executed automatically

Kris

Quoting Femke De Backere <femmyke at gmail.com>:

> Hi!
> 
> I have a really strange problem with my ruleflow. I have a ruleflow 
> 
> process with some workhandlers. The flow seems to work perfectly,  
> until I arrive at the timer. The timer itself executes well, if it  
> delays for a period of only 4 milliseconds. The flow stops running on
>  
> the join component (because I don't reach the workhandler CheckRass, 
> 
> in the debugging).
> 
>   If I give the timer a delay period of 1 minute (60 000  
> milliseconds), the flow stops running at the timer component. The  
> action nodes before and after the timer contain print statements and 
> 
> in this case I never reach the printstatement after the timer.
> 
> I really don't understand why my flow stops running at these points, 
> 
> as I never reach an end node. Does anyone see the problem? (I added a
>  
> printscreen of my ruleflow)
> 
> Thx!
> 
> Femke
> 
> If I