[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message]

Re: Excessive layering in XML Schemas

  • From: Michael Kay <mike@saxonica.com>
  • To: "Costello, Roger L." <costello@mitre.org>
  • Date: Mon, 10 Aug 2015 13:16:19 +0100

Re:  Excessive layering in XML Schemas
Not specific to XSD, but I have often resisted excessive layering in object model designs and I have usually ended up regretting it. The real world is complex, and you ignore the complexity at your peril.

Michael Kay
Saxonica


On 10 Aug 2015, at 13:10, Costello, Roger L. <costello@mitre.org> wrote:

Hi Folks,

 

Below is a slight twist on something that Eric Raymond wrote [1].  I welcome your thoughts on this topic.  What schemas have you seen that have excessive layering?  /Roger

 

XML Schema make abstraction easy — perhaps too easy. It encourage data architectures with thick glue and elaborate layers. This can be good when the problem domain is truly complex and demands a lot of abstraction, but it can backfire badly if schema designers end up doing simple things in complex ways just because they can.

Too many layers destroy transparency: It becomes too difficult to see down through them and mentally model what the data design is actually doing. The Rules of Simplicity, Clarity, and Transparency get violated wholesale, and the result is a data design full of obscure bugs and continuing maintenance problems.

This tendency is probably exacerbated because a lot of educational courses teach thick layering as a way to satisfy the Rule of Representation. In this view, having lots of abstract types is equated with embedding knowledge in your data. The problem with this is that too often, the ‘smart data’ in the glue layers is not actually about any natural entity in whatever the schema is representing — it's just about being glue. (One sure sign of this is a proliferation of abstract subclasses or ‘mixins’.)

 

[1] http://www.catb.org/esr/writings/taoup/html/unix_and_oo.html




[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index]


PURCHASE STYLUS STUDIO ONLINE TODAY!

Purchasing Stylus Studio from our online shop is Easy, Secure and Value Priced!

Buy Stylus Studio Now

Download The World's Best XML IDE!

Accelerate XML development with our award-winning XML IDE - Download a free trial today!

Don't miss another message! Subscribe to this list today.
Email
First Name
Last Name
Company
Subscribe in XML format
RSS 2.0
Atom 0.3
 

Stylus Studio has published XML-DEV in RSS and ATOM formats, enabling users to easily subcribe to the list from their preferred news reader application.


Stylus Studio Sponsored Links are added links designed to provide related and additional information to the visitors of this website. they were not included by the author in the initial post. To view the content without the Sponsor Links please click here.

Site Map | Privacy Policy | Terms of Use | Trademarks
Free Stylus Studio XML Training:
W3C Member
Stylus Studio® and DataDirect XQuery ™are products from DataDirect Technologies, is a registered trademark of Progress Software Corporation, in the U.S. and other countries. © 2004-2013 All Rights Reserved.