[rules-users] Re: Re: Defining facts declaratively with TypeDeclaration and assert facts from java

[Ronald Brindl]

Thanks for your reply!
Compile time is not an option, since the metamodel might change during
runtime.
One non functional requirement is also to keep the metamodel/model free from
technology dependent stuff, because the same metamodel/model is used in
different parts of the system, among them might be other rule engines
(partially plugged in by client, partially old legacy code).

Thanks, 
ron.


Greg Barton wrote:

> Have you considered using hibernate?  You could generate the pojos at
> compile time, so they can be jarred up and sent to guvnor.  You can
> specify the interfaces the pojos must implement in the hibernate mapping
> file, if you want to go that route.  And of course all of the db access
> interception via proxy is handled by hibernate as well.
> 
> --- On Mon, 2/9/09, Ronald Brindl <rbrindl at thegoldensource.com> wrote:
> 
>> From: Ronald Brindl <rbrindl at thegoldensource.com>
>> Subject: [rules-users] Re: Defining facts declaratively with
>> TypeDeclaration and assert facts from java To:
>> rules-users at lists.jboss.org Date: Monday, February 9, 2009, 9:17 AM
>> Thank you!
>> 
>> I already saw that piece of documentation (i am looking at
>> trunk), and that
>> was what lead me into that direction.
>> However, is there some possibility to get access to the
>> generated classes? I
>> mean, our application (and the domain model classes) is
>> potentially
>> distributed among several JVM's. So what i am looking
>> for is that the DRL
>> declarations are generated in our application during
>> startup, then they are
>> deployed to guvnor to allow business user use the facts,
>> and then have the
>> generated classes at the application side again, to feed
>> the facts. Is this
>> possible somehow, or am i going in the wrong direction?
>> 
>> I also still have the problem, that there SHOULD be the
>> possibility to
>> intercept attribute access to the facts, to make lazy
>> loading of attributes
>> from the database possible.
>> So maybe the better solution is to generate interfaces,
>> give them to guvnor
>> and implement the access logic to incoming messages and
>> existing messages
>> in the db with a proxy.
>> I dont want to go via XML in any way if i can avoid it...
>> 
>> However, i will have a look at the spots you pointed out
>> and see, what i
>> find there...
>> 
>> Thank you,
>> ron.
>> 
>> Edson Tirelli wrote:
>> 
>> >    Ronald,
>> > 
>> >    Last week I wrote the docs for TypeDeclaration. So,
>> you may try the
>> >    docs
>> > first hand and provide me feedback! ;)
>> > 
>> >
>>
https://hudson.jboss.org/hudson/job/drools/lastSuccessfulBuild/artifact/trunk/target/docs/drools-expert/html/ch06.html#d0e3047
>> > 
>> >    The API was promoted from drools-core to drools-api
>> after M5 was
>> > released, so you need trunk to use it.
>> > 
>> >
>>
https://hudson.jboss.org/hudson/job/drools/lastSuccessfulBuild/artifact/trunk/target/
>> > 
>> >    Regarding your questions, I believe this is
>> probably the easiest way of
>> > doing it, but not the only one. Just to mention
>> another way would be to
>> > generate a JAXB domain model from your database and
>> upload it as a jar to
>> > Guvnor.
>> > 
>> >    If you want to dive into Drools internals and see
>> how the classes are
>> > generated, take a look at
>> org.drools.factmodel.ClassDefinition in
>> > drools-core as your starting point. From there you can
>> navigate through
>> > the code searching for the references. IMO though, you
>> don't need to go
>> > down this route.
>> > 
>> >    Regarding the pipeline, if you want to customize it
>> for your needs, you
>> > just need to create an intermediate step or use smooks
>> to map from one
>> > model into the other. I think mark did not added a
>> step to map from an
>> > external model into a type declared model yet.
>> Contributions welcome.
>> > 
>> >    Hope this helps,
>> >         Edson
>> > 
>> > 
>> > 
>> > 2009/2/6 Ronald Brindl
>> <rbrindl at thegoldensource.com>
>> > 
>> >> Referring to threads
>> >>
>> http://thread.gmane.org/gmane.comp.java.drools.devel/2860
>> >>        Dynamic Facts: how to get jar wih Facts
>> declared in drl
>> >>
>> http://thread.gmane.org/gmane.comp.java.drools.devel/2595
>> >>        TypeDeclaration plugin heirarchy
>> >>
>> >> I am just in the process of evaluating the
>> possibilities of using Drools.
>> >>
>> >> Our use case is the following:
>> >> We have a dynamic metamodel, which gets generated
>> from database during
>> >> application initialisation phase.  Then a runtime
>> model gets
>> >> instantiated, which is fed from incoming messages
>> (files, jms, etc.)
>> >> Both models are highly generic, basically maps of
>> maps (lists of lists,
>> >> for model instances)
>> >>
>> >> Now, i would like to publish the metamodel to
>> Guvnor as fact model, so
>> >> that business rules users can use it there and
>> define
>> >>
>> >> In the last 2 days i dived into the sources, read
>> the mailing list
>> >> entries above, documentation and so on, but i
>> still don't have a clear
>> >> vision on how to accomplish that.
>> >>
>> >> Our first approach was to use TypeDeclaration,
>> i.e. to dynamically create
>> >> DRL that defines the fact types as defined in our
>> metamodel, but i don't
>> >> have a clue on how to assert data for those types,
>> since i don't have the
>> >> resulting java classes available in Java.
>> >> (There was also some confusion: in the
>> documentation (M5) it says,
>> >> bytecode is generated for declaratively defined
>> Facts, but i could not
>> >> find anything in the code, where this byte code is
>> generated)
>> >>
>> >> Our next approach was to generate interfaces as
>> Fact types and create
>> >> proxies to access the data. This would also allow
>> us to implement another
>> >> use case, that demands access to messages already
>> stored in the database
>> >> with the same id as the incoming messages, and
>> compare what fields are
>> >> new and to provide merging of new and old data.
>> >>
>> >> I also had a quick look at the new Pipeline
>> concept, but as far as i
>> >> understand that, it builds on a statically defined
>> FactModel.
>> >>
>> >> Then i dived a little bit more into the code and
>> saw code generation for
>> >> accessing Java class facts, which also might be a
>> reasonable solution for
>> >> us.
>> >>
>> >> However, what i was asking myself was, if there is
>> some entry point for
>> >> functionality like that, some existing API.
>> >>
>> >> Thank you,
>> >> ron.
>> >>
>> >>
>> >> --
>> >> Ronald Brindl
>> >> Sr. Software Developer
>> >> Member of Architecture Team
>> >> The Goldensource Corporation
>> >>
>> >> _______________________________________________
>> >> rules-users mailing list
>> >> rules-users at lists.jboss.org
>> >>
>> https://lists.jboss.org/mailman/listinfo/rules-users
>> >>
>> > 
>> > 
>> > 
>> 
>> --
>> Ronald Brindl
>> Sr. Software Developer
>> Member of Architecture Team
>> The Goldensource Corporation
>> 
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-- 
Ronald Brindl
Sr. Software Developer
Member of Architecture Team
The Goldensource Corporation