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Re: XML catalog draft




>Date: Thu, 30 Jan 97 10:57:43 CST
>From: paul@arbortext.com (Paul Grosso)
>Subject: Re: XML Catalog draft proposal
>
>> From: James Clark <jjc@jclark.com>
>> 
>> >1.  In the XML WD1.0, a system identifier is a URL.  However, the 
>> >    current catalog draft chooses not to put this restriction on 
>> >    the "right hand side" of a catalog entry, though a URL continues 
>> >    to be the most obvious thing to use there. 

...

>Allow me to explain some of the concerns we discussed on this issue.
>It may be that the ERB will see a way to address these concerns.
>
>1.  It was a goal to allow the catalog to map public identifiers into
>    URNs.  (Do we want to open up the defn of sysids in XML to include
>    URNs, or does the defn of URL already include URNs?)
>
>2.  It was a goal to allow XML catalogs to be used with SGML/XML
>    repositories (aka databases).  For example, it was felt important
>    to allow an entry such as:
>   PUBLIC "corporate legal boilerplate C312" "<corpdb>get_bplate('C312')"
>    where the rhs is some database call (whether expressed in FSI syntax
>    as in this example or not).
>
>3.  It was a goal (albeit a less important one) to allow catalogs to 
>    have FSIs on the rhs. 
>
>4.  Though URLs remain the most obvious thing for a sysid to be, it
>    might make sense to allow the market to decide what sysids will
>    work.  This is one place where it might be best to suggest that
>    URLs give maximum interoperability, but to allow other things
>    to develop.  After all, any decent XML tool that finds a sysid
>    that isn't a URL is going to try its best to figure it out anyway,
>    so how is restricting it in the XML spec going to help?

Your points 2 to 4 apply equally to system identifiers and were considered
when deciding whether to restrict system identifiers to URLs.  They don't
provide any justification for treating the RHS of a catalog entry
differently from a system identifier.

As for 1, I don't think the issue of how URNs are going to fit into the XML
framework has been decided. Adding SGML public identifiers and catalogs to
XML complicates this significantly.  Before we add public identifiers to
XML, I think we need to have a clear picture of how URLs, URNs, FPIs,
non-formal public identifiers, system identifiers and catalogs all fit
together.  I'm still unclear.

James