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RE: [xml-dev] Using Wrapper Elements in Schemas - Any Best Practices?

I would say this is common practice. The reason you mention is one reason, although this is a design-time issue, in that you know that you need the attributes when you decide whether to add the wrapper. There is also a use-time issue - it is much easier to iterate over the "symptom" elements in XSL if they are in a wrapper (especially if there are other "symptom" elements around in the document). I can't see any downside apart from a minor increase in document size. I am sure others can come up with other benefits.

Paul Spencer
CTO, alphaXML Ltd
author: Professional XML Design and Implementation (Wrox Press)
co-author: Beginning XML, Professional XSL (Wrox Press)
XML services for industry and Government
+44 (0)1491 630053

-----Original Message-----
From: Magick, Brian [mailto:Brian.Magick@COMPAQ.com]
Sent: 24 September 2001 15:38
To: xml-dev@lists.xml.org
Subject: [xml-dev] Using Wrapper Elements in Schemas - Any Best Practices?

Are there any best practices for using wrapper elements in XML Schemas?  We are having an internal debate on the merits of using wrappers, I summarize my opinions below.

The debate……should a set of symptoms be represented by a series of symptom tags alone or should they be contained in a <symptoms> wrapper element.



<symptom> This is symptom 1 </symptom>

<symptom> This is symptom 2 </symptom>

<symptom> This is symptom 3 </symptom>



My initial thoughts:  I think wrappers are useful when you need to group some tags and possibly need a lead wrapper element to capture some attributes or metadata.  For example (yes this might be a bit silly) perhaps we want to know the symptoms based on how long they have been persisting.  Maybe some symptoms have been around for 7 days and other for just 3.  The following XML, using wrapper elements, accomplishes the description of this quite well.


<symptoms duration=”3”>
  <symptom>runny nose</symptom>

<symptoms duration=”7”>
  <symptom>stomach ache</symptom>


Of course, this is just my opinion, and one I would like some community backing for before I espouse this as a “best practice” within my organization.  This might just be a matter of style, but I’m interested in how other developers are determining this.


Brian Magick