xml-dev - Linking (using embed) and XML Schema

["Roger L. Costello" <costello@mitre.org>]

Hi Folks,

Suppose that I have an XML document that is created by assembling XML
data from various sources, using XML Link (with show="embed").  For
example, we may create an XML document to show stock quotes, where the
quotes are gotten from, say, three different sources.

Such a document raises interesting questions with regards to the XML
schema for that document.  Does the schema describe the structure of the
document *after* the embeddding process has occurred (post-embed), or,
does the schema describe the structure of the document *before* the
embedding process has occurred (pre-embed)?  

For example, does the schema describe this version of the document (the
post-embed version):

<?xml version="1.0">
<stocks xmlns="stocks.xsd">
   <stock>
      <tickername>MSFT</tickername>
      <company.name>Microsoft Corporation</company.name>
      <current.price>85 5/8</current.price>
      <change>+13/16</change>
      <previous.close>84 13/16</previous.close>
   </stock>
   <stock>
      <tickername>AAPL</tickername>
      <company.name>Apple Corporation</company.name>
      <current.price>55 3/4</current.price>
      <change>0</change>
      <previous.close>55 3/4</previous.close>
   </stock>
   <stock>
      <tickername>HD</tickername>
      <company.name>Home Depot</company.name>
      <current.price>61</current.price>
      <change>-1 3/8</change>
      <previous.close>62 3/8</previous.close>
   </stock>
      <tickername>LU</tickername>
      <company.name>Lucent Technologies</company.name>
      <current.price>65 7/16</current.price>
      <change>-1 5/16</change>
      <previous.close>66 3/4</previous.close>
   </stock>
</stocks>

Or, does the schema describe this version of the document (the pre-embed
version):

<?xml version="1.0">
<stocks xmlns="stocks.xsd">
   <source show="embed"
           href="http://www.quote.yahoo.com"/>
   <source show="embed"
           href="http://www.stocks.com"/>
   <source show="embed"
           href="http://www.altavista.stktker.com"/>
</stocks>

Another interesting question is: can we specify (in the schema?) that
the XML parser should validate the pre-embed version versus the
post-embed version?

>From my cursory look at the XML Schema it appears that this problem has
not been addressed.  Is it going to be addresssed in later working
drafts?  Any comments on this problem?  /Roger


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