Ø  Why not a single Pattern?

Ø      fact:InsertedFactPOJO(countdownLatch == 0) If (and only if) there is not more than a single InsertedFactPOJO in WM it doesn't matter (except confuse readers) but otherwise it produces more or less disturbing effects.

 

Interesting.  For my case (luckily?)  I have a flow of control that definitely only includes a single InsertedFactPOJO in WM.

 

Where can I best isolate my Drools readings, sample exercises et. al. Drools discovery efforts so that I can (some day) competently answer your question “Why not a single pattern?”  …. Is there a place in the Drools literature that explicitly addresses these “disturbing effects”?

 

THANKS WOLFGANG!

 

-----Original Message-----
From: rules-users-bounces@lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Wolfgang Laun
Sent: Friday, November 30, 2012 2:22 AM
To: Rules Users List
Subject: Re: [rules-users] DROOLs 'Guarded entry/block' tactics for Rules synchronization and ordinality?

 

On 30/11/2012, Greg Barton <greg_barton@yahoo.com> wrote:

> Not a problem.  Actually I prefer to perform flow control using

> working memory objects like that instead of using the keywords, but I'm old school.

> :)

> 

> GreG

 

Agenda groups provide a mechanism that's difficult to emulate using "guard objects", i.e., the stack-ish behaviour, with automatic return to the previously active group once all activations of the current group are exhausted.

 

>> From: "Cotton, Ben" <Ben.Cotton@morganstanley.com>

>> 

>> I now want to (competently!) use DROOLs language tactics that give me

>> ever finer grained control over managing rule set firing behavior on

>> Fact mutation events.  Specifically, I want to be able to implement

>> some form of ‘Guarded entry/block’ controls.

 

There may be some good reason for "fine grained control" every now and then, but basically this contravenes the fundamental idea of rules being perfectly capable of determining the right order - if written correctly, that is, by judiciously selecting fact properties by constraints.

 

>> rule "RULE_ALL_RULES_HAVE_FIRED_ONCE_ORDINALLY"

>> when

>>     fact:InsertedFactPOJO()

>>     InsertedFactPOJO(countdownLatch == 0) then

 

Why not a single Pattern?

    fact:InsertedFactPOJO(countdownLatch == 0) If (and only if) there is not more than a single InsertedFactPOJO in WM it doesn't matter (except confuse readers) but otherwise it produces more or less disturbing effects.

 

-W

 

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