Re: Are people really using Identity constraintsspecified in X
There is also the alternative of using CLiX/xlinkit, which gives you a powerful constraint language, an optimised execution engine, and a great editor. If you're going to have a large number of rules, having an editor for them will make you happy, especially if you're getting sick of XPath: http://www.systemwire.com/articles/workbench-preview.html http://www.clixml.org regards, Christian Nentwich > As an alternative to Schematron at least some people might find it worth > looking at the XForms model. Rather like Schematron it allows you to define > constaints based on XPath expressions. It also works well with W3C XML > Schema. So, if you already have a schema, it is possible to tighten it up > further. XForms Model Item Properties allow you to constrain and calculate > values for XPath expressions, and to define in what circumstances a nodeset > evaluates to required, relevant and/or readonly. > There is nothing in XForms that says you can only use a model with a form. > In fact it is possible to build models that process XML all on their own. > All the best > Mark Seaborne >> From: "Dare Obasanjo" <dareo@m...> >> Date: Mon, 16 Aug 2004 14:52:28 -0700 >> To: "Cox, Bruce" <Bruce.Cox@U...>, "Bullard, Claude L \(Len\)" >> <len.bullard@i...>, "Roger L. Costello" <costello@m...>, >> <xml-dev@l...> >> Subject: RE: Are people really using Identity constraints specified >> in XML schema? >> >> The first question is whether an XML schema should be used to enforce >> these constraints. Once you decide that then the next step is to use >> schematron. Once you hit the limitations of that you're in 'writing >> custom code at the various end points' land. Most developers skip the >> Schematron step. >> >> -- >> PITHY WORDS OF WISDOM >> Bills travel through the mail at twice the speed of checks. >> >> This posting is provided "AS IS" with no warranties, and confers no >> rights. >> >>> -----Original Message----- >>> From: Cox, Bruce [mailto:Bruce.Cox@U...] >>> Sent: Monday, August 16, 2004 2:41 PM >>> To: Bullard, Claude L (Len); Roger L. Costello; xml-dev@l... >>> Subject: RE: Are people really using Identity >>> constraints specified in XML schema? >>> >>> I, for one, am very interested in discussing these issues further. >>> Since XML Schema data typing cannot express all the business >>> rules that constrain, for example, patent document numbers >>> (from about 100 issuing offices), what other technologies can >>> be invoked that would? What combination of technologies >>> should be used, and in what order, to accomplish the goal? >>> I'm interested in standards-based technologies, such as XML >>> Schema, to express such rules in a fashion that removes as >>> much variation as possible among systems that implement them >>> around the world. Should we use a repository for the rules >>> and their implementations? >>> >>> Is anyone else interested? >>> >>> Bruce B. Cox >>> U.S. Patent & Trademark Office >>> SA4XMLT >>> +1-703-306-2606 >>> >>> -----Original Message----- >>> From: Bullard, Claude L (Len) [mailto:len.bullard@i...] >>> Sent: Friday, August 13, 2004 12:35 PM >>> To: 'Roger L. Costello'; xml-dev@l... >>> Subject: RE: Are people really using Identity >>> constraints specified in XML schema? >>> >>> Michael is right, but this isn't a one size fits all decision. >>> Loose filters allow dirt to seep into the system. The >>> architectural question is what are the right places to put >>> such rules into a system? >>> We are aware of different technologies for this, and it is a >>> good thread to out the issues if that interests the members >>> of this list. >>> >>> That a technology can accomplish a task doesn't mean it is >>> the right tech for that task. It doesn't mean it isn't. >>> I suspect this is another task situatedness issue, but given >>> a services architecture, one might want to inquire about >>> tasks relative to their roles in distributed processes that >>> are candidates for orchestration. >>> >>> len >>> >>> >>> From: Roger L. Costello [mailto:costello@m...] >>> >>> Michael Kay wrote: >>> >>>> I tend to be a little wary of constraints myself. >>>> Many of those you see in student textbooks are misguided. >>> If I see a >>>> schema (XML or RDB) with the constraint that employees must be over >>>> 16, I ask myself what the IT department would do if the business >>>> decided to hire someone under 16. If there's a rule that an >>> employee's >>>> manager must themselves be an employee, I ask what would >>> happen when >>>> someone is told that they now report to a contractor. >>> >>> This is excellent: >>> >>>> It's not the job of computers to limit what people are >>> allowed to do >>>> (or the job of the IT department to regulate the business). >>> >>> The following innocuous sentence has profound implications on >>> the role of schemas: >>> >>>> A guideline I use is that constraints should be there only >>> to protect >>>> the IT system itself from data that it cannot handle. >>> >>> Would you elaborate upon this sentence Michael? I believe >>> that you are saying that the role of a schema is to define >>> things such as: >>> - ensure that a "date" is indeed a valid date >>> - ensure that an "age" is indeed a valid age >>> >>> The role of a schema is not, for example, to specify: >>> - the "age" must be at least 16. >>> >>> So, your guideline says: use schemas to specify datatypes for >>> objects, not their range of values. Is that a fair summary >>> of your guideline? /Roger >>> >>> >>> >>> ----------------------------------------------------------------- >>> The xml-dev list is sponsored by XML.org >>> <http://www.xml.org>, an initiative of OASIS >>> <http://www.oasis-open.org> >>> >>> The list archives are at http://lists.xml.org/archives/xml-dev/ >>> >>> To subscribe or unsubscribe from this list use the subscription >>> manager: <http://www.oasis-open.org/mlmanage/index.php> >>> >>> >> >> ----------------------------------------------------------------- >> The xml-dev list is sponsored by XML.org <http://www.xml.org>, an >> initiative of OASIS <http://www.oasis-open.org> >> >> The list archives are at http://lists.xml.org/archives/xml-dev/ >> >> To subscribe or unsubscribe from this list use the subscription >> manager: <http://www.oasis-open.org/mlmanage/index.php> >> >> > The information in this e-mail is sent in confidence for the > addressee only and may be legally privileged. 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