If you insert POJOs as facts in Jess, you'll have to write a
   (deftemplace X (declare (from-class X)))
and the fields available for pattern matching in rules rely on the JavaBeans convention.

I have (quite successfully) used POJOs resulting from unmarshalling an XML document (via JAXB) as facts, both in Drools and in Jess; most certainly without writing any "copycat" fact classes and tedious transformations.

As for globals: They play the same role in Drools as in Jess; in neither system are they part of the working memory.

I don't know what you could mean by a "standard fact class".

As for iterating over all fact objects in Drools' WM, Drools provides getObjects() in WorkingMemory; or you could set up a query and run this.

-W


On 10 September 2010 14:54, Donald Winston <satchwinston@yahoo.com> wrote:
I'm reviewing JBoss Rules (Drools) for an application I'm starting to build. It appears that the only way to assert facts is to use the insert(Object) method where the object is a bean using the proper naming conventions for it's properties. There also appears to be a way to use arbitrary objects using globals but do these end up in the fact base? It's disturbing to me that I have to create a bunch of classes whose sole purpose in life is to support the rule base. This is similar to using java server pages and having to create a bunch of classes just to support each page. That's why I don't use java server pages and use xsl transformations instead. I want to use my xml jdom document to represent my data and not have to create a bunch of beans. I can't seem to find anything in the api where I can assert facts without creating my own custom classes. There's no standard Fact class?

I've been also experimenting with Jess and it provides an easy way for me to do this. I just iterate through my jdom document and create Fact objects and assert them. I can then execute the rules and then iterate through the updated fact base using engine.listFacts() and update my jdom document. It couldn't be easier or more natural. Is there an analogous way to do this in Drools?


Thank you very much.
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