[rules-dev] Knowledge Composition and Parts

[Mark Proctor]

I'm in the process of doing the final changes to drools-api. Having done 
the spring work, not yet committed, I liked their resource framework, so 
decided to copy this for Drools. So we now have:
KnowledgeBuilder.add( Resource, KnowledgeType, ResourceConfiguration );

Where we support the following Resource sources:
FileSystemResource, ClassPathResource, UrlResource ByteArrayResource, 
ReaderResource, EncodedResource and InputStreamResource

In use it'll look like:
kbuilder.add( ResourceFactory.newClassPathResource( "somefile.drl", 
classLoader ), KnowledgeType.DRL )

I do not yet do knowledge type inference from the .ext - I think I'll 
leave that till after 5.0, if I do it at all.

So kbuilder.addResource( URL, ...) and kbuilder.addResource( Reader, ... 
) from M3 no longer exist and are as above.

What I'm adding now is the ability to provide an xml file that is a 
configuration of resources to load. The term Configuration is 
overloaded, and we use this more to provide the directives for 
knowledgebuilder and knowledgebase. So I was thinking Composition and 
Part - for Knowledge Composition and Knowledge Part, from dictionary.com 
on "composition":
"the act of combining parts or elements to form a whole."
"the composition of “aircraft” from “air” and “craft.”

My reasoning for this is a composition will contain rules, processes, 
decision tables, dsls etc. "The KnowlegeBase is a composition of 
Knowlege Parts".

The XML would look like:
<composition>
<part resource="classpath://........" type="DRL">

<part resource="file://........">
<decisiontable-configuration type="XLS" worksheet-name="blah" />
</part>
</composition>

I have not added a resource type attribute, as we will assume it must 
start with protocol. classpath will use ClassPathResource, file will use 
FileSystemResource and anything will be a UrlResource. This would be a 
special KnowlegeType. I may later make the type optional, once we can 
infer the type from the .ext.
kbuilder.addResource( ResourceFactory.newFileResource( 
"/data/my-knowledge.xml" ), KnowledgeType.COMPOSITION );

What do people think?

Mark