I've tried to think up a few annotations as an alternative to the Bean
introspection for deriving Jess templates from Java classes.
Given that you can use BeanInfo and/or write your own extension of
ReflectionClassResearcher I'd say that the extra effort isn't really
worth it - unless you could add some additional features. These,
however, would require supporting extensions to classes in jess (and,
therefore, could not be implemented by a mere userfunction).
Here is what I've come up with. Perhaps interesting, but no "killer
application" as far as I can see. (I guess that the JessProperty is just
syntactic sugar,
because you could call such methods with a test CE.)
JessTemplate( name=<template-name>,
module=<module-name>,
isSlotSpecific=<boolean>,
isBackchainReactive=<boolean>,
factoryClass=<class>,
factoryMethod=<method-name> )
factoryClass and factoryMethod can be used to create the Java object behind
the shadow fact from Jess' assert.
JessSlot( name=<slot-name>,
defaultMethod=<method-name>,
defaultClass=<class> )
May be on a field or a method. defaultClass/defaultMethod may be used to
produce the default value.
JessPreModify()
Method in the template class, to be called before an update from Jess.
JessPostModify()
Method in the template class, called after an update from Jess.
It is possible for this method to send a PropertyChangeEvent,
so this may be omitted from the set methods for individual slots.
JessProperty()
A boolean method with this annotation acts as a property
that can be used in a conditional element as a "fact-level
predicate constraint" (Jess extension).
Example: Define a fact predicate constraint.
//Example: Code fragment
@JessTemplate
public class Car {
@JessSlot
protected int seat;
@JessSlot
protected int price;
//...
@JessProperty
public boolean eligible(){
return seat >= 5 && price <= 10000;
}
}
A rule about a Car could now contain
(defrule buyCar
?car <- (Car :eligible)
=>
(printout t "buy: " ?car.id crlf)
)
Cheers
Wolfgang
Skeptic 2000 wrote:
Yeah, I knew about BeanInfo classes, but after using them for a while,
I'm not too satisfied (usability).
Of course I could write some code that produce a Deftemplate, but what
I'm interested in is a solution that include JessDE working accordingly.
That's why I was thinking about replacing the default Bean
introspection mechanism, but I'm not even sure it would work for JessDE.
Thanks again.
------------------------------------------------------------------------
> From: [EMAIL PROTECTED]
> To: [email protected]
> Subject: Re: JESS: using annotations
> Date: Wed, 16 Jul 2008 10:04:27 -0400
>
> Jess 7.1 still supports JDK 1.4, so annotations aren't available.
> Future Jess versions will support Java 5+ .
>
> I like the fact that Jess supports the JavaBeans spec; it's nice to be
> able to refer people to that for details. It's one less "invention"
> that needs to be maintained by us.
>
> It's not true, of course, that you're restricted to following naming
> conventions, as JavaBeans includes the BeanInfo concept for describing
> variances from the conventions.
>
> In any case, the jess.Deftemplate class has a complete public API;
> you should be able write a Userfunction in Java which turned classes
> into Deftemplates following annotations using whatever scheme you
> like. If you do this, and describe it in our Wiki, then other people
> could use it too!
>
>
> On Jul 15, 2008, at 11:54 PM, Skeptic 2000 wrote:
>
> >
> > Hi,
> >
> > Have you considered using annotations instead of naming scheme to
> > create deftemplates associated to shadow facts ?
> >
> > Do you think it would be difficult thing to "hack" ?
> >
> > Thanks.
> >
> >
>
> ---------------------------------------------------------
> Ernest Friedman-Hill
> Informatics & Decision Sciences, Sandia National Laboratories
> PO Box 969, MS 9012, Livermore, CA 94550
> http://www.jessrules.com
>
>
>
>
>
>
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