[rules-users] Hold the Beans!

[Wolfgang Laun]

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 at 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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