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Subject: Re: Repesention of table in an XML-DTD
From: Peter Flynn <[log in to unmask]>
Reply-To:General discussion of Extensible Markup Language <[log in to unmask]>
Date:Wed, 30 Sep 1998 10:23:25 +0100

TEXT/PLAIN (51 lines)

> Why to use externalID = SYSTEM here. One could very well do by using :-
> <!ENTITY row-001  "<row
> pos='001'><ident>foo</ident><desc>barstool</desc></row>">

When I read the original request, I got the feeling that there was an
attempt here to avoid the processor having to download/read all the
rows of a big table when only a few were actually going to be needed.

Putting the data in internal entities in the DTD still means the whole
table gets read before anything can happen. In fact the byte count
would be rather greater than otherwise because of the declaration. A
processor could be expected to cache a DTD for reuse from instance to
instance, so this penalty would only occur once...but how often is the
table data updated?

Would it not be possible to say:

<!ENTITY row-001 SYSTEM "row-001.frag">
<!ENTITY row-002 SYSTEM "row-002.frag">

etc, where {filename}.frag contained:

   <row pos='002'><ident>bar</ident><desc>footender</desc></row>

etc? This makes the DTD content smaller and faster, and pushes the
speed penalty back down to the (sparse?) row-requests issued by the
application when it reads &row-nnn; in the instances.

> <?xml version="1.0" ?>
> <DOCTYPE start [
> <!ENTITY % bar-table PUBLIC "-//Amit Rekhi//ENTITIES for the bar-table//EN"
> "table.ent">
> %bar-table;

Yep, or indeed, stuff all the entity declarations into table.ent, certainly.

> <!ELEMENT start (#PCDATA)
>  ]>
> <start>&row-001;</start>

Using separate files is also a penalty on the generating host application.

Will this work under current parser conditions (ie do they do the same
as regular SGML parsers and only check the syntax of general entity
declarations, rather than try to resolve the identifier and check the
existence of the file?


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