[rules-users] IllegalAccessError in shadow classes

[Godmar Back]

A general solution with arbitrary, user-defined fact types such as the
one you propose would indeed be nice, but as you say requires
significant implementation effort.

Simply supporting maps in addition to beans should be simple (in a
sound and properly encapsulated design) and may give a significant
portion of the benefits, considering that a) many Java libraries
already use standard collection classes centered around maps and b)
even if they don't, they can be easily converted into Maps without
requiring tedious code generation in the way your current bean-only
approach does.

My 2c.

 - Godmar

On Wed, Feb 20, 2008 at 5:39 PM, Edson Tirelli <tirelli at post.com> wrote:
>
>    Godmar,
>
>    Ok, now I understood what you mean. This ability to use Maps as a
> "special" type of facts requires the implementation of what we call
> "pluggable fact types". It is something we wanted to have for ages, but it
> is not implemented yet. Unfortunately it is not as "easy" as it may appear,
> but definitively it is a must have for the future, specially as we move to
> the ontology space.
>     You are right to think that this will give us another level of
> expressive power. Among several other advantages, it would allow the the
> user instead of writing patterns like:
>
>    Map( this.factType == "SomeFactType", ... )
>
>    Where "factType" is a key in the Map, to simply write rules:
>
>    SomeFactType( ... )
>
>    More than that, once we have such feature, we can directly use any
> structure mappable into a Java class as a fact, like Grrovy/Jython/Whatever
> beans, CSV files, XML documents, etc.
>     So, it is REALLY powerful and really cool!
>
>    Our only limitation is indeed "(wo)man power"... :)
>    Seriously speaking, we already have pluggable dialects, pluggable
> evaluators and an "almost pluggable" extractor framework. All of them are
> pre-reqs for the pluggable fact types, but we did not reached that point
> yet.
>
>    Talking about the project, the team is now committed to deliver support
> to CEP applications (including temporal reasoning and stream management),
> support to higher levels of ruleflow and process modeling, improving the
> whole BRMS and repository tools, plus we have Master Degree and PhD students
> working on Machine Learning, Decision Trees, Uncertainty Reasoning, Temporal
> Reasoning and Rulebase Static Analysis.
>     As you can see there is a LOT on our plate, so if anyone wants to step
> up and help us accelerate the development of pluggable fact types, it is
> more than welcome.
>
>    ANYONE up to the task? :)
>
>    Regarding your question about the removal of shadow fact, yes, it is
> scheduled for the next major release in a few months time. Although, it is
> import to remember that you can already disable shadow facts, just by
> following some requirements. I will write another e-mail about that.
>
>    []s
>    Edson
>
>
>
> 2008/2/20, Godmar Back <godmar at gmail.com>:
> >
> >
> >
> > I think that you *should* treat facts that implement java.util.Map
> > differently from other facts.
> > Ignore their concrete class and don't worry about applying your
> > shadowing algorithm.
> > Then, treat them as if they were beans with getXYZ() methods for each
> > key "XYZ" they contain.
> >
> > Your reply indicates that you haven't even considered this design. I
> > wonder why not?  (It seemed so natural to me that I assumed it's what
> > Drools *must* do. Especially considering the fact that Drools's chosen
> > scripting language, MVEL, supports accesses to maps using a special,
> > javascript-like syntax that allows you to verify that accesses are
> > side-effect free.)
> >
> >
> > On Wed, Feb 20, 2008 at 4:11 PM, Edson Tirelli <tirelli at post.com> wrote:
> > >
> > >     A blog I wrote a long time ago about dynamically generated beans:
> > >
> > > http://blog.athico.com/2006/12/dynamically-generated-class-beans-as.html
> > >
> >
> >
> > I'm aware that I can generate beans - dynamically or statically, but
> > that is exactly the hassle I had hoped to avoid. (And, quite frankly,
> > it's not something I should have to go through when using a framework
> > such as Drools.)
> >
> > Will the issue disappear in a future, shadowless version of your
> > engine? To what degree will this version depend on facts being
> > conforming Java beans?
> >
> >
> >   - Godmar
> >
> > _______________________________________________
> > rules-users mailing list
> > rules-users at lists.jboss.org
> > https://lists.jboss.org/mailman/listinfo/rules-users
> >
>
>
>
>
> --
>   Edson Tirelli
>   JBoss Drools Core Development
>   Office: +55 11 3529-6000
>   Mobile: +55 11 9287-5646
>   JBoss, a division of Red Hat @ www.jboss.com
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