Correction... I inadvertantly stated Drools/JRules in my previous e-mail when I meant to say Drools/JBRules...
________________________________ From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Shahad Ahmed Sent: Friday, May 11, 2007 9:58 AM To: Rules Users List Subject: Re: [rules-users] Sequential rules algorithm Dave, Thanks for the suggestions. I think giving each rule in the sequence the same activation-group (I may have incorrectly said agenda-group in my original email) would be a bit like the semaphore you described. When one rule in an activation-group fires then all the other rules in the group are disabled. I'll give this a try and see what the performance is like. I'm actively looking into what would be involved in adding a sequential mode to Drools. I've been using commercial rules engines like Ilog JRules in various projects for a couple of years, but the latest addition to Drools such as a BRMS and Ruleflow (with GUI) has definitely made me take Drools much more seriously as a "contender" in the business rules space. Regards, Shahad On 5/11/07, Hamu, Dave <[EMAIL PROTECTED]> wrote: Shahad, In addition to using salience, you would also need to use a semaphore. I am not sure JBoss (Mark P., et. al.) have implemented a "sequential mode" which is a feature that is provided by both JRules and Blaze Advisor (among others); however, that would be a nice feature to add to the rules engine. It seems that without massive changes to the product, they could allow a rule-base to be loaded with a "sequential-mode" property in which case, the RETE engine would be disabled. I'm not really up to speed on the LEAPS feature and whether it is being obsoleted... However, I just read Mark's response and I respectfully disagree... I believe that you can simulate sequential processing with salience and a semaphore. Basically, if the rules in question have a salience order and the working memory is changed using a semaphore construct, then any subsequent rules beyond the first rule that fires would not execute. So, if I understand the issue that you have, say that there are many thousands of rules, but you want them evaluated in a specific order. Once the first rule fires, you can mark the data as processed and preclude the execution of any additional rules. There may be other issues from a performance perspective, but ultimately, I think that this workaround is very doable. On the other hand, I applaud Mark's suggestion to have a member of the JRules community take the lead on a sequential-mode algorithm for JRules 4.0... I have been a fan of the Drools/JRules project since the 1.x days and I have witness this project evolve from an intriguing tool-kit to a impressive product and I think that your suggestion is fantastic. Providing this additional feature will further position JRules as a leading contender in the Business Rules space. Regards, Dave ________________________________ From: [EMAIL PROTECTED] [mailto: [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> ] On Behalf Of Shahad Ahmed Sent: Friday, May 11, 2007 8:34 AM To: [email protected] Subject: [rules-users] Sequential rules algorithm Does anyone know if there's an efficient way of replicating the Ilog JRules sequential algorithm in Drools? From a (over simplified) users perspective, the JRules sequential algorithm takes an ordered list of rules and fires the first rule in the sequence with a valid IF condition. You can also specify a maximum number of rules in a sequence that may fire. If you have a large number of simple rules to be fired in sequence (often precondition validating rules in a complex ruleflow), then the sequential algorithm gives a significant performance gain over the RETE algorithm in JRules. I can see how you might order a set of rules by salience and give then the same agenda group. Then I assume you will get the equivalent "behaviour" to the Ilog sequential algorithm described above. However, before I try this out, I thought I'd ask if anyone has a view on the performance of this approach; and whether there would be anything to be gained by adding a similar sequential algorithm to Drools. I've seen a few Blog posts in the past that suggest that the Ilog sequential algorithm is similar to LEAPS, but I don't know if that's accurate - also LEAPS will no longer be supported on Drools 4.0 development path. Thanks Shahad _______________________________________________ rules-users mailing list [email protected] https://lists.jboss.org/mailman/listinfo/rules-users
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