2010/8/24 Edson Tirelli <tirelli@post.com>

    Wolfgang, 

    The requirement for serializable classes even when not using persistence was a "mistake" made several versions ago and I believed it was fixed. What version of Drools are you using? If that is trunk, we need to fix it.

The latest official release 5.1.

 
    Anyway, workaround: for count(), you can simply write "count(1)" instead of using the actual variable,

Good to know. OTOH, is there any good reason for count() having an argument at all? Just because all others have an argument? Nowadays, the uniform signature could be (Object... objs) which would, e.g., permit you to write count() without the dummy argument. Others, such as sum, average and especially min and max could easily handle more than one argument. Not a bonanza, but being general is not a bad thing...

-W

 

    Edson

2010/8/23 Wolfgang Laun <wolfgang.laun@gmail.com>

No, not knowingly :-) I'm using the simplest possible setup for KnowledgeBase, KnowledgeBuilder, StatefulKnowledgeSession.

Why should accumulate/count effect persistence?

-W


2010/8/23 Swindells, Thomas <TSwindells@nds.com>

You’ve probably configured your system to be using persistence?

In which case what you are persisting needs to be serializable so that it can be persisted

 

Thomas

 

From: rules-users-bounces@lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Wolfgang Laun
Sent: 23 August 2010 12:17
To: Rules Users List
Subject: [rules-users] counting facts of a kind

 

As simple as it gets:

rule countHigh
when
    $n : Number() from accumulate ( $sgc : StartGoalConn() count( $sgc ) )
then
    System.out.println( "plain routes: " + $n );
end

And yet, it fails:

Exception in thread "main" org.drools.RuntimeDroolsException: java.lang.ClassCastException: rss.ixl.route.TrainStartGoalConn cannot be cast to java.io.Serializable

Sure, adding "implements Serializable" to StartGoalConn fixes this. But why is this necessary?

FYI, StartGoalConn is abstract superclass of TrainStartGoalConn - just in case this has some bearing on this issue.

Best
-W




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--
  Edson Tirelli
  JBoss Drools Core Development
  JBoss by Red Hat @ www.jboss.com

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