[rules-users] can't put formula on Guvnor screen

[Michael Anstis]

In an ideal world you should not normally need to think about sequencing
the order of rule execution. I suspect you are thinking "procedurally".

The "WHEN" part of a rule is evaluated as Facts are inserted into Working
Memory. This causes Activations for the "THEN" part to appear on an Agenda
(schedule).

When you call "fireAllRules" the Activations on the Agenda are executed. If
an Activation causes a change to the Facts is Working Memory rules' "WHEN"
parts are re-evaluated and either new Activations added to the Agenda (e.g.
if you modify an existing Fact, insert a new one etc), or possibly other
existing Activations removed (e.g. if you retract a Fact or a change causes
a previous match to no-longer be valid). There is a nice flow-chart in the
Drools Expert documentation explaining this and Truth Maintenance.

Production Rule Systems are meant to be used such that you place all your
Knowledge (Facts) into its Working Memory and after a bit of churning your
results appear :)

If however you really need to order the execution of the Activations you
can use Salience, Agenda Groups or a Process Flow (and possibly others, I
forget).

jBPM is now the de-facto Process Engine integrating with Drools. Rule Flow
was jBPM's predecessor and AFAIK should be considered deprecated.

There are others much more qualified on this forum to suggest best practice
and the comment on the pit-falls of trying to sequence rules' execution.

Hopefully they can also give you some advice.

With kind regards,

Mike

On 16 May 2012 10:27, San <sangram.jy at gmail.com> wrote:

> Hi Mike
>
> I am working along with Zeeshan and Aswin. I hav started exploring drools a
> month back n finished 3 products  one using the .drl rule and two using
> decision table. They have joined while exploring guvner just 2 days back n
> we have raised that bug.
>
> But nw we have a new requirement , for which i posted under *"How to
> control
> the order of rule execution"*.
>
> I am also started explorin jBPM since the rule flow file which I uploaded
> is
> nt able to open in guvnor.
>
> Pz suggest us a way hw to proceed for the same in drools.
>
>
> Sangram
> Java Developer, India
>
>
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