[rules-users] Efficiency of using inline evals in Drools 5

[Edson Tirelli]

   Nancy,

   An inline eval will create a constraint in the corresponding node in the
network. I.e., if it is an alpha constraint, the eval() will be added to an
alpha node, or if it is a beta constraint, it will be added to the beta
node.

   If it is an alpha constraint, it will be reevaluated every time the fact
type changes (in your example, every time the engine is notified of a change
in a User fact). If it is a beta constraint, it will be reevaluated every
time the fact changes or a fact matching a previous pattern in the same rule
changes.

   Evals are not indexed, so the reevaluation is a bit more costly. It is
better to avoid them when possible, but sometimes it is not.

   []s
   Edson

2009/7/28 Nancy Dougherty <nancyhd at stanford.edu>

> Hello!
>
> I have a question about how an inline eval function is or isn’t
> efficient in the algorithm-  I have many User objects that I am
> inserting into Working Memory (in a stateful session), and each User
> object has as ArrayList of Messages
>
> The message class has 2 String fields: text and logid
>
> I have custom boolean function user.containsText(String keyword)
> function that takes in a string, and searches to see if that keyword
> contained in the text field of one of the message entries in the User
> message arraylist.  If I use an inline eval statement to implement
> this:
>
> $user: User( eval (containsText ( “sample text”) ) )
>
> Will it re-evaluate each time?  Or will Drools cache the result and
> remember it/ create a node based on it so the node will have every
> user this is true for, and it doesn’t re-evaluate when the users or
> rules are modified?  Will it create a "node" in the algorithm for all
> the users that this function is true for?
>
> On a similar note, if I use the “matches” comparator in a rule
> creation, does it create a node and cache the result? Will it
> automatically re-evaluate each time the field its matched against is
> modified?
>
> Thanks so much!
>
> Nancy
>
> _______________________________________________
> rules-users mailing list
> rules-users at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>



-- 
 Edson Tirelli
 JBoss Drools Core Development
 JBoss by Red Hat @ www.jboss.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.jboss.org/pipermail/rules-users/attachments/20090728/1870e3f6/attachment.html