Re: [xml-dev] Stability of schemas -- frequency of versioning

[John Cowan <johnwcowan@gmail.com>]

Please stop spamming this list.  One posting is appropriate, six are not.

Thank you.

On Thu, Feb 16, 2012 at 1:04 AM,  <w3c@drrw.info> wrote:
> Roger,
>
> This is but one reason of many that people are preferring to use CAM
> templates for validation.
>
> 1) CAM has dynamic structure constructs so you can accommodate variants in
> what your information exchange partners are doing - e.g. 500 trading
> partners sending what they think is valid XML per schema - you can handle
> that with ONE template
> 2) CAM is fault tolerant - it issues warnings and errors - so your
> processing does not fail and break
> 3) It can do extended checking and validations that schema alone cannot
> 4) It has SQL table lookups so you can check dynamic data - customer
> numbers, part numbers, etc.
> 5) It uses dictionary collections so you can align your component
> definitions across schema collections
>
> See working examples and more - http://www.cameditor.org
>
> Enjoy, DW
>
>
> -------- Original Message --------
> Subject: [xml-dev] Stability of schemas -- frequency of versioning
> From: "Costello, Roger L." <costello@mitre.org>
> Date: Mon, November 21, 2011 7:58 am
> To: "xml-dev@lists.xml.org" <xml-dev@lists.xml.org>
>
> Hi Folks,
>
> How frequently should schemas be allowed to change?
>
> Let "schemas" refer to XML Schema, Relax NG, DTD, or Schematron.
>
> Let "change" refer to non-backward compatible changes such as requiring a
> new element.
>
> I will attempt to persuade you of the following:
>
> To be effectively deployed, schemas require a certain amount of stability.
> That is, they shouldn't change too often. Further, any changes that do occur
> should be backward compatible.
>
> That says, for example, that if your domain is Books then the kind of
> information that goes into Books is stable; if your domain is financial
> contracts -- swaps, options, futures -- then the kind of information that
> goes into financial contracts is stable. Consequently your schemas are
> stable. Conversely, if your Book or financial contract schemas are
> constantly changing then your schema development and software development
> will thrash and users will be constantly confused.
>
> An example of a rock-solid schema is the XML Schema for XML Schemas. It
> hasn't changed in 10 years. And the new version is backward compatible with
> the old. Ditto for the Relax NG schema for Relax NG schemas.
>
> Suppose, however, that the information for a domain is required to
> frequently change, say, three times a year. I have attempted to persuade you
> that a schema may not be a good fit for describing that type of information.
> But I am at a loss for what is a good fit. What is a good fit?
>
> /Roger
>
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