Re: locating schemas via public ids

[Lauren Wood <lauren@softquad.com>]

On 23 Jan 2001, Paul Grosso wrote:
> Below is what I'm suggesting we submit to the XML Schema WG.  We'd
> need to send it soon, so please give comments asap.  
> 
> Also, to what extent do we need to check with the OASIS AC rep before
> we send this to the XML Schema WG.  And, since OASIS is a W3C member,
> but OASIS is an outside organization, should we be involving the XML
> CG in this interchange or not?
> 
> My suggested answers:  Lauren should tell Laura what we're doing and
> we should plan to cc her on the email we send.  We (Lauren or her
> designate--I'm willing if designated) should inform the XML CG and cc
> them on the email to XML Schema.

I think this is a good plan. Normally I think I should be the person 
to carry out all the parts of this; however since I will be out of email 
contact from Thursday until Tuesday Feb 6th, I would prefer if 
someone else can handle this, copying me on any 
correspondence. Paul, I am happy to designate you for this 
position. I will email Laura about our plans before I leave.

The suggested email seems fine to me.

Lauren


> ----------------------------------------------------------------
> The OASIS Entity Resolution Technical Committee (OERTC) [1] is
> chartered to developed an entity resolution catalog format in XML (XML
> Catalog or xmlcat).  The purpose and functionality of this catalog
> format is to cover that which the SGML Open/OASIS TR9401 [2] Entity
> Management Catalog did, but using XML instance syntax and tailored for
> use with XML.
> 
> Many implementors and users have found public ids and entity
> management catalogs to be very usefulness in practical situations
> ranging from individual use to major production environments, and
> there is a desire to be able to use such techniques for accessing XML
> resources, especially "public" resources such as published DTDs and
> Schemas.  The OERTC has the support of several implementors, and its
> work has received interest from the xml-dev community.
> 
> During our work, we realized that the current Schema Structures
> draft appears to make it impossible to provide schema-locating
> hints using anything other than URIs.  Specifically, public
> identifiers [3] could not be used as the spec is currently written.
> 
> In Structures, 6.3.2 How schema definitions are located on the Web
> [4], it says:
>   [xsi:schemaLocation] records the author's warrant with pairs of URI
>   references (one for the namespace URI, and one for a hint as to the
>   location of a schema document defining names for that namespace
>   URI). [xsi:noNamespaceSchemaLocation] similarly provides a URI
>   reference as a hint as to the location of a schema document with no
>   targetNamespace.
> 
> The problem is that each member of schemaLocation and the value of
> noNamespaceSchemaLocation is required to be a URI.  Furthermore, the
> members are undelimited and separated by spaces, and public
> identifiers can contain spaces.
> 
> The XML Catalog (as did TR9401 before it) would allow a user
> to locate a resource using all the information that might be 
> known about it (name, system id, public id), and certainly schema
> resources will be given public ids (several have already [5]).  But
> this only works if there is some way to include that information in
> schemaLocation.
> 
> Therefore, the OERTC asks [6] that the XML Schema WG make allowances
> in schemaLocation for specifying both public and system ids [7].
> 
> paul
> 
> [1] http://www.oasis-open.org/committees/entity/
> [2] http://www.oasis-open.org/committees/entity/9401.html
> [3] http://www.w3.org/TR/REC-xml#NT-PubidLiteral
> [4] http://www.w3.org/TR/2000/CR-xmlschema-1-20001024/#schema-loc [5]
> http://www.oasis-open.org/committees/entity/ident.html#schema [6]
> OASIS is a W3C member organization [7] Not to presume to constrain a
> solution to the problem, but
>     even something such as the following might be acceptable:
>     Say that each member--that is currently a URI--is optionally
>     delimited by quotes and consists of either a SystemLiteral
>     (production 11 in XML 1.0) OR the second half of the
>     disjunction in production 75, to wit:
>       'PUBLIC' S PubidLiteral S SystemLiteral
>     (which, since it contains spaces, would necessarily be quoted).