[rules-users] Re: rules-users Digest, Vol 28, Issue 19

[Ricardo Gil Alcañiz]

Thanks for the explanation!

I've found the CR1 downloads, I've just tried it, and it works just as I
needed :).

Just one comment. In my first attempts I missed your comment about using a
variable with the specific name "processInstance"... I'm "slower" than I
thought... But, just as a suggestion, it may be better to have a clearer way
to use this special matching. Maybe using a fact property or a keyword... ?
Well, I don't know anything about the ruleflow project and its complexity so
take my suggestion as it is :).

Well, thanks again for the help and congratulations for your impressive
work!

Ricardo.

2009/3/9 Kris Verlaenen <kris.verlaenen at cs.kuleuven.be>

>  Ricardo,
>
> This method has recently been added into WorkflowProcessInstance, it is on
> trunk and will be in CR1.  For M5, you could indeed use
> WorkflowProcessInstanceImpl ...
>
> Kris
>
> ----- Original Message -----
> *From:* Ricardo Gil Alcañiz <rgil at okode.com>
> *To:* Rules Users List <rules-users at lists.jboss.org>
> *Sent:* Monday, March 09, 2009 4:37 PM
> *Subject:* [rules-users] Re: rules-users Digest, Vol 28, Issue 19
>
>  Thanks for your fast response Kris and Michal!
>
> I tried to use your solution Kris, but I've found that 5.0.0 M5
> WorkflowProcessInstance does not seems to provide getVariable method. I've
> found that method into WorkflowProcessInstanceImpl searching in svn trunk. I
> must work with that class or I missed something? Thanks again!
>
> Ricardo.
>
>
>> ---------- Mensaje reenviado ----------
>> From: Kris Verlaenen <Kris.Verlaenen at cs.kuleuven.be>
>> To: Rules Users List <rules-users at lists.jboss.org>
>> Date: Sun, 8 Mar 2009 03:56:29 +0100
>> Subject: Re: [rules-users] Drools Flow, constraint parametrization
>> Ricardo,
>>
>> If you need to access process variables and have only simple constraint
>> expressions, I suggest you use code constraints (Java or MVEL dialect),
>> as they have direct access to variables (and globals).
>>
>> If you want to use rule constraints anyway (because your constraints can
>> become rather complex), there are a few options:
>>
>>  - You cannot use globals to pass information used in your constraints,
>> because globals are considered immutable with respect to rule conditions
>>
>>  - You can put your data you want to access in your working memory.
>> Rule constraints can then access this info just like any normal rule.
>>
>>  - You access the variable value using the special "processInstance"
>> rule constraint (I just added a new section in the documentation to
>> explain):
>>
>> Rule constraints do not have direct access to variables defined inside
>> the process. It is however possible to refer to the current process
>> instance inside a rule constraint, by adding the process instance to the
>> working memory and matching to the process instance inside your rule
>> constraint. We have added special logic to make sure that a variable
>> "processInstance" of type WorkflowProcessInstance will only match to the
>> current process instance and not to other process instances in the
>> working memory. Note that you are however responsible yourself to insert
>> (and possibly update) the process instance into the session (for example
>> using Java code or an (on-entry or on-exit or explicit) action in your
>> process). The following exampleof a rule constraint will search for a
>> person with the same name as the value stored in the variable "name" of
>> the process:
>>
>> processInstance: WorkflowProcessInstance()
>> Person( name == ( processInstance.getVariable("name") ) )
>> # add more constraints here ...
>>
>> Kris
>>
>> Quoting Ricardo Gil Alcañiz <rgil at okode.com>:
>>
>> > Hi,
>> >
>> > I'm not a new drools user but I started to test rule flows (5.0M5)
>> > recently
>> > and I'm stucked, so any clue will be welcomed :). I'm testing how to
>> > share a
>> > StatefulKnowledgeSession between N rule flow instances. I'm trying
>> > to
>> > parametrize each instance with process variables at start time but I
>> > don't
>> > know how to use them from rule constraints (in event waits, splits,
>> > etc.).
>> > I've read the documentation and I've found this text related to
>> > constraints
>> > "Both rule and code constraints have access to globals that are
>> > defined for
>> > the process and can reuse imports at the process level." I tried it
>> > assigning (from an action) a variable value to a global variable but
>> > it's
>> > not working for me. ¿I'm missing something?
>> >
>> > Thanks in advance!
>> >
>> > Ricardo.
>> >
>>
>
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