[rules-users] Declarative fact model or Java?

Fri Jan 20 13:26:10 EST 2012

With Guvnor, you can also use "working set" (see here ) to restrict the availiable fields to expose to a business user, by selecting class and/or fields of an existing class, and even more (businnes contraints on values, with rules). 

The only problem I see with working sets, is that you must explicitely set the working set to use when you create your rule (not very natural for a business user). 
So, if one create a new rule from Guvnor, he can access the whole object model. The fact model filtering is not enabled until a working set is associated. 

May be one day, for a package or a category (or a user as said in the doc for future devs), we will be able to set a default working set, so that all rule of this package will automatically associated with filterered model. 
But it could be a good solution for you, avoiding complex proxies, factories and so on ... 

----- Mail original -----

De: GPatel at tsys.com 
À: "Rules Users List" <rules-users at lists.jboss.org> 
Cc: rules-users-bounces at lists.jboss.org 
Envoyé: Vendredi 20 Janvier 2012 18:59:02 
Objet: Re: [rules-users] Declarative fact model or Java? 

If you are starting from scratch, this is possible. However, I find myself having to expose operations from the *preexisting* technical domain into the business (i.e expose methods from existing technical domain code that has all kinds of annotations and code references to 3rd party software). The only way out, in that case, is to have your own separate business domain classes that wrap around (proxy) the existing technical domain 

From: Wolfgang Laun <wolfgang.laun at gmail.com> 
To: Rules Users List <rules-users at lists.jboss.org> 
Date: 01/20/2012 06:36 AM 
Subject: Re: [rules-users] Declarative fact model or Java? 
Sent by: rules-users-bounces at lists.jboss.org 

Let me mention that I've used Java classes derived from XML Schema 
as facts. 

If there are technical properties you'd like to hide from the rule programmer, 
define a "business" type and extend it with the technical properties. The 
rule programmer must make do with the "business" type, which is 
possible even if the object (fact) type is the "technical" subclass. 

-W 

On 20/01/2012, Stephen Masters <stephen.masters at me.com> wrote: 
> Hi Davide, 
> 
> Thanks for your thoughts. The application is just a service which takes an 
> XML request, converts that into a fact and inserts that into the working 
> memory. Based on rule evaluations, it responds to the client with more XML 
> indicating whether the requested action is permitted. 
> 
> On of the key aims of the project is to enable management of some rules by 
> 'the business' through Guvnor. The current 1-1 mapping you mention is partly 
> what put me off using Java models, as it leads to 'technical' attributes 
> being present in the Guvnor fact model, which are not relevant to the 
> business. The more I can keep the fact model within Guvnor minimal, the 
> better. 
> 
> So following your logic, given that: 
> There is no legacy model to deal with. 
> ~80% of what is going on will be within Drools, with the Java code just to 
> insert/update facts and marshal XML. 
> I would really like to avoid a 1-1 mapping of Java classes to DRL facts. 
> ... I think I'll stick with DRL facts. 
> 
> Given that I'm not too sure exactly what I want out of it yet, I'm not sure 
> how much I could contribute to a spec, but I'd be happy to help out with 
> things. If only by testing out early code and providing feedback. If there's 
> anything you think I might be able to help out with, feel free to ping me an 
> email. 
> 
> Many thanks, 
> 
> Steve 
> stephen.masters at me.com 
> 
> 
> On Jan 20, 2012, at 11:44 AM, Davide Sottara <dsotty at gmail.com> wrote: 
> 
> Hi Steve, 
> let me share my thoughts on this. 
> 
> You will probably want to use a Java model when it's already available :) Or 
> when you're using the rule engine to implement the business logic layer of 
> your application, processing data coming from an external source. 
> 
> A DRL model, instead, is definitely recommended for "temporary" facts, or 
> data structures which are used by the rules to do their computations. 
> The main problem with DRL fact classes is that they're quite cumbersome to 
> use outside the rule engine. On the other hand, you will be sure that the 
> declared types will correspond to an implementation fully compatible and 
> optimized for the rule engine. 
> 
> Very roughly : if the rule engine is a component in a larger architecture, 
> use java classes. If you're building a rule-based application - i.e. DRL is 
> your programming language and Drools is your execution environment, go for 
> DRL. 
> 
> As for mapping, we have added this very experimental feature lately: 
> 
> http://blog.athico.com/2011/12/new-feature-spotlight-traits-part-1.html 
> http://blog.athico.com/2011/12/dynamic-typing-in-rules-traits-part-2.html 
> 
> I have plans to use annotations to improve the mapping, avoiding the 1-1 
> correspondence between fields, so if you want to contribute, if only to the 
> specifications, let us know :) 
> 
> Best 
> Davide 
> 
> -- 
> View this message in context: 
> http://drools.46999.n3.nabble.com/rules-users-Declarative-fact-model-or-Java-tp3675001p3675181.html 
> Sent from the Drools: User forum mailing list archive at Nabble.com. 
> _______________________________________________ 
> rules-users mailing list 
> rules-users at lists.jboss.org 
> https://lists.jboss.org/mailman/listinfo/rules-users 
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