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RE: Schema constraints from a different file?

• To: xml-dev@l...
• Subject: RE: Schema constraints from a different file?
• From: Dmitry Epstein <mitia@n...>
• Date: Tue, 25 Oct 2005 00:38:32 -0500
• In-reply-to: <Pine.LNX.4.61.0510231130300.10000@m...>
• References: <200510220929.j9M9T2cG003011@p...><Pine.LNX.4.61.0510231130300.10000@m...>

At 10:44 AM 10/23/2005, you wrote:
Basically, I would like to develop schemas that impose
>>>constraints on an element or attribute in one XML file based on
>>>element or attribute values from another XML file.  Is this at
>>>all possible?  I would consider making a file containing just a
>>>list of all available item IDs, if that would help solve the
>>>problem.
>
>Theoretically, I think this could do the trick:
>
>   (1) Include the XML document that contains IDs into the document that
>       refers to them via a parsed external entity [XML Rec, 4.2.2, 4.3]
>
>   (2) Use WXS key/keyref feature [WXS, Part 1, 3.11] to encode your
>       referential constraints.
>
>(1) will physically keep the data in separate files, but the processor 
>should pull them together, so the schema (2) could be written as if the 
>data was present in a single file.

Let me see if I understand.  The external entity could look like this:

<item id="abc123"/>
<item id="def456"/>
...

Then in some other XML document the DTD will include these lines:

<!ATTLIST item id ID #REQUIRED>
<!ENTITY itemlist SYSTEM "itemlist.xml">

and later in the body of the document:

<items>&itemlist;</items>

Something like this?

But if I am already using a DTD to describe my document, can I use a schema 
as well?

• Follow-Ups:
  • RE: Schema constraints from a different file?
    • From: Vladimir Gapeyev <vgapeyev@s...>
  • RE: Schema constraints from a different file?
    • From: "Rick Jelliffe" <rjelliffe@a...>

• References:
  • RE: Schema constraints from a different file?
    • From: Vladimir Gapeyev <vgapeyev@s...>

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