Comments on Drools & jBPM: Writing better rules (Edson Tirelli)

Is all your tips valid for drools 5 too?please upd...

2009-11-03T15:52:02.144Z

Is all your tips valid for drools 5 too?please update this valuable post.

thanks,
David Bakkar

thank you

2009-08-18T19:01:47.927+01:00

thank you

Hi, I did the following and it seemed useful at th...

2009-01-13T10:40:00.000Z

Hi, I did the following and it seemed useful at the time -

(a) Disregarded concepts like Inputs and Outputs to the Rule Engine - instead propagate the concept of a KnowledgeBase that undergoes some changes (becomes richer) as the rules fire. Spent almost as much time on thinking about the KB as about the rules.

(b) Visualized the KnowledgeBase as a set of distinct XMLs, with tags and values in plain English, not more than two nestings per XML, maybe more than one XML.

(c) Considered whether the KB to rules interaction would work even if the rules fired in a non-sequential unordered manner.

(d) Wrote the rules first in plain English. As atomic as possible.

(e) Asserted individual classes (once I JAXBed all those XMLs into classes) separately into Working Memory, but not the collections, which remained (hopefully as flat objects) inside each definite class.

(f) Working with strings and other immutable classes always means "retract and re-insert" rather than update.

(g) Minimized use of salience, but used activation-groups and no-actives whenever logic looked bunched or layered.

I hope this may be of use to someone at the point of designing the rules set-up.

There are many outsource writing services provider...

2008-04-08T12:22:00.000+01:00

There are many outsource writing services providers are there online.. But when you select a provider for your custom business writing you must be very careful. A good business writing can improve and grow your business.. Gramatical or punctuation errors in your custom business writing causes bad impression on you//

I would consider #2 lack of nested property access...

2007-03-22T00:01:00.000Z

I would consider #2 lack of nested property access a rule Anti-pattern. In practice, you can't always change the object model, so some times it is nice to be able to access a nested attribute like customer.address.zipCode. The problem is that it creates more problems than it solves. Normally, when an object is asserted, engines like clips, jess and many others will cache the value of the attribute. If the rule language allowed users to access a nested field, should it make a deep copy of the object when it caches the values? Doing that is costly, so most engines do a shallow copy.

From a rule patterns and practice perspective, it's generally better to explicitly assert the fact and match on the object.attribute. when that isn't practical, it may be better to create a Busines object model like JRules BOM that flattens the model and makes it easier for reasoning.

Yes, these are some of the "expressiveness limitat...

2007-03-15T16:44:00.000Z

Yes, these are some of the "expressiveness limitations in the language" I was talking about in version 3.0.x. We are working on removing these limitations (and many of them were already removed) in 3.1 and beyond, so please keep tuned and providing us with feedback. It is very important for us to know real use cases and user needs.

While I accept the thrust of your article, the thr...

2007-03-15T15:04:00.000Z

While I accept the thrust of your article, the three biggest obstacles that I see currently to widespread adoption of the JBoss rules syntax in business are: 1) lack of basic boolean operations in conditions and 2) the lack of nested property access and 3) the lack of proper null handling. These make it very difficult to write realistic business rules on anything close to a plain Java object model.

I an glad to see that Michael and Mark are working on these issues (#1 and #2 have been partially addressed) and I think we should all encourage this line of refinement, even if it does not live up to the purist usage of the engine ;)

thanks,
Pat Niemeyer