Hi Justin. I read your postings regarding the XML language with great interest.
Last year I also needed the Drools XML language for a similar usecase: simply transforming custom rules (defined by JPA Entity metdata) to xdrl files. Like you, I also read the Drools documentation where it described that XML is a possible solution to this. Like you said, it looked like the right tool for the job - including xsd validation. So I started developing but soon stumbled across some missing functionality within the XML parser. Posting to the mailing list showed that xml shouldn't be used anymore. Since these were minor parsing problems and development was half-way through, I contributed some patches to make it work. Sadly, development at our company was stopped abruptly last year, so I couldn't move on/finish the project. Now our company plans to continue that work. So I am also interested in possible alternatives. We haven't such complex scenarios as you describe - only simple expressions by now. We used Drools 5.1 with the XML patches I mentioned before. I would appreciate if you could post the results of your discussion with Edson and Mark to the mailing list. So I might rethink finishing the project with XML. At the latest when it comes to upgrading Drools to the current version I'm afraid we have to move to an alternative. BTW: +1 for updating the Drools documentation regarding XML support. Regards Veit Am 11.01.2012 08:10, schrieb Justin Holmes: > Mark and Edson, > > Thank you both for prompt responses. I certainly understand your position on > the Drools XML language, and I also agree that using an open standard would > have its benefits going forward. Now that we know DrlDumper is only intended > to be a debugging tool, and that it does not work in future versions, we will > need to rethink our solutions. Edson, I'll email your redhat.com account and > hopefully we can chat sometime on Wednesday. > > Additionally, I have a request regarding documentation. If it has been > decided that Drools XML is dead and that no one should be allowed to revive > it, Red Hat documentation must reflect that decision. Currently, the Drools > 5.4.Beta Expert User Manual (section 5.11) and the BRMS 5.2 reference guide > (section 4.11) say, "All the features are available with XML that are > available to DRL." Both docs also prescribe the use of XmlDumper, DrlDumper, > DrlParser, and XmlPackageReader for round-trip translations between XML and > DRL. It is clear from post on the user-list that others have been mislead by > the docs as well, so we should see to it that they are fixed. If there is a > better avenue to request that all 5.x docs be updated, please let me know. > > Once again, thanks for your help. I'm sure we will be in touch in the coming > days. > > Regards, > --- > Justin Holmes > Red Hat Consulting > 410.599.8432 : mobile > http://www.redhat.com/consulting/ > ________________________________________ > From: rules-dev-boun...@lists.jboss.org [rules-dev-boun...@lists.jboss.org] > On Behalf Of Edson Tirelli [ed.tire...@gmail.com] > Sent: Tuesday, January 10, 2012 7:30 PM > To: Rules Dev List > Subject: Re: [rules-dev] Drools XML Language and Tools Development > > Just to add to Mark's comments, there are options for you to move forward. > > The main bit that probably got you off track is the DRLDumper. That class > was used mainly for debugging purposes. No code in Drools makes use of it, > and because of that, we didn't have any extensive tests in place for it... > result is it broke and no one noticed until a couple months ago. I will try > to take some time to fix it for 5.4 (it is wrong in 5.2/5.3) or just remove > it completely, as again, it is not used by drools itself... it was just a > debugging utility class we used some time ago. > > Regarding the options for this customer, I suggest we move this discussion > to an internal thread. Open a ticket or mail me directly on the corporate > e-mail and we can continue from there. > > Regards, > Edson > > On Tue, Jan 10, 2012 at 6:39 PM, Mark Proctor > <mproc...@codehaus.org<mailto:mproc...@codehaus.org>> wrote: > Rule base systems typically had simple languages. Data structures where > either list or frames, the number of constructs are very limited. Complex > expressions, such as nested accessors did not exist - like with Drools 3.0. > That made it very easy to support a 1 to 1 mapping in xml. > > Around Drools 4 out langauge become more expression, we started to allow > complex expresisons inside of patterns. In Drools 5.3 that is even more so. > It quickly became obvious that xml representation fo drools would also need a > representation for java expressions, this was going to be a lot of work - > especially as we would probably have to change a lot of the existing xml. > > It seems very few people are using the xml, certainly no one seemed to care > about it. Xml parsers and schemas is something that every java developer can > do, but no one has come forward maintain this. So we've let it die. > > I'm not sure I'd want to resurrect it, for a one of piece of work. It's > likely the maintainenance of this would soon fall back on the core developers. > > I think I'd rather see xml efforts around RuleML and/or RIF. So imho if you > want to do anything, do it around those. The downside is that representing > our more powerful constructs like sliding time windows may not be possible in > those languages, and you would need to define extensions. > > Mark > > On 10/01/2012 22:08, Justin Holmes wrote: > Hello Devs, > > My name is Justin Holmes and I'm a Middleware Consultant for Red Hat. I'm > currently staffed on an engagement that provides a very interesting use case > for Drools. In particular, our teams currently believes that the Drools XML > Language would be the best possible solution for one of our problem. We are > aware that the Drools XML language has not been developed for sometime and is > considered deprecated. Additionally, the application will need to support > Drools CEP functionality in the near future. Before we begin crafting a > custom solution, we would like to ask: > 1) Is the XML language truly the best option for our use case? > 2) If it is the best option, how do we begin developing the XML language and > tools (XMLPackageReader) to fully support at least BRMS 5.2? > > Context: > Client is using Drool 5.1.1 and we are migrating to BRMS 5.2. There are two > independent workflows of interest: > > 1) Rule Authoring and DRL generation: The rule assets and metadata are kept > in a custom format (both relational DB and XML) in order to decouple it from > the runtime. Thus, the client wrote their own GUI and content manager instead > of using Guvnor. The custom GUI allows business users to author 3 types of > content, as well as rules for these types of content, using a guided-rule > editor with domain specific language. The following steps occur when a user > wants to produce a new version of a rule: > i) GUI saves LHS rule logic in an XML database using MathML > (http://www.w3.org/Math/), and then saves everything else in a relational > database. > ii) iBATIS pulls down the corresponding database and XML entries and > populates POJOs. There is 1 class definition per content type. > iii) Cumbersome application code translates POJOs into Drools PackageDescr > (~5000 lines of code, not using fluent API). This step produces a very > strange and convoluted representation of the LHS of each RuleDescr. It works > with DrlDumper 5.1.1 but does not work properly with the BRMS 5.2 version of > DrlDumper (MVEL Template). This is the source of our problem. > iv) PackageDescr is dumped into a valid DRL string with Drools DrlDumper > v) Custom content manager does some versioning and then stores DRL in an XML > database > > 2) Deployment and Runtime: App is deployed daily and will have dozens of > runtimes during that 24 span. When deployed, it pulls all rules from the > database and builds several KnowledgePackages, which are cached, and then > used throughout the day. > > > > > > Proposed Solution: > > Because the app code that performs step iii) is so convoluted and will need > to be modified in order to support CEP, we want to pursue a more maintainable > solution to provide the translation and abandon the mess that is already in > the application. We feel that rewriting this code with the fluent API is just > as dangerous as the present code. Additionally, the rules are far too > variable to use Rule templating. > > > > So, we propose to translate the client's custom rule assets and metadata into > the Drools XML Language, parse the XML and dump out DRLs. We will likely need > to use the existing intermediate POJOs for this. The most difficult piece in > the puzzle by far is translating the LHS of rules, and of course this is the > part that is broken currently in our system. We believe that it should be > MUCH easier to translate the well formatted MathML representation of the LHS > to the Drools XML schema using XSLT, than to translate it to PackageDescrs > with Java code. There are also the additional benefits of validation and > portability presented by XML. The downside here is that the XML language and > tools are out of date, so we would need to develop these solutions first. > > > > > > Both consultants on this project have been interested in contributing to the > Drools project and we feel this could be the perfect entry point. We realize > this is a complicated question and presenting it over email is limiting, so > please feel free to contact me by phone. > > > > > > Thank you, > > --- > Justin Holmes > Red Hat Consulting > 410.599.8432<tel:410.599.8432> : mobile > http://www.redhat.com/consulting/ > > > > > > _______________________________________________ > rules-dev mailing list > rules-dev@lists.jboss.org<mailto:rules-dev@lists.jboss.org> > https://lists.jboss.org/mailman/listinfo/rules-dev > > > > _______________________________________________ > rules-dev mailing list > rules-dev@lists.jboss.org<mailto:rules-dev@lists.jboss.org> > https://lists.jboss.org/mailman/listinfo/rules-dev > > > > > -- > Edson Tirelli > JBoss Drools Core Development > JBoss by Red Hat @ www.jboss.com<http://www.jboss.com> > > _______________________________________________ > rules-dev mailing list > rules-dev@lists.jboss.org > https://lists.jboss.org/mailman/listinfo/rules-dev _______________________________________________ rules-dev mailing list rules-dev@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-dev
