xml-dev - Re: XSchema question

[Peter Murray-Rust <peter@ursus.demon.co.uk>]

At 17:41 04/08/98 -0700, Don Park wrote:
[...]
>
>Anyway, it is clear to me at this point that XSchema does not address
>'dynamic-schema' and 'inline-schema'.

Actually I think it does - although I may people aren't going to be
comfortable with the former - rather like self-modifying code.

If I understand you you want to have a schema/DTD that changes dynamically
with time, driven by the contents of the (changing) document. This is not
common in traditional SGML where the DTD is used to constrain documents to
a pre-conceived format. Your approach is to review the contents of the log
file and change the DTD/schema to reflect them. It isn't common to generate
DTDs from documents but there is a tool called FRED from OCLC which
apparently does this. Of course a human could also do it.

XSchemas can be 'inline' in that being an XML document they can be included
(using the entity mechanism:

<!DOCTYPE MyLog [
<!ENTITY myschema SYSTEM "myschema.xml">
]>
<MyLog>
&myschema;
... rest of log file ...
</MyLog>


This includes the content of the myschema.xml file, so it's part of the
tree. It cannot be dynamic. If you want it dynamic you could use something
like:

<MyLog>
<schemaLink xml:link="simple" show="embed" actuate="user"
href="myschema.xml"/>
... rest of log file ...
</MyLog>

We haven't yet defined the syntax or mechanism whereby an XSchema gets
'used' and you are welcome to devise your own. So the second syntax would
allow you to link to the (dynamically updated) myschema.xml file at
arbitrary intervals. The file could change in the meantime.

If this is what you want to do you'll probably have to write your own
system for managing it because I guess it's not commonly done in SGML.

	P>


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