RE: Why is XBase needed?

First of all, let me apologize for not responding earlier.  My response has
in the XML Base disposition of comments draft, but I expected would be
completed and made public shortly after the last call period ended.  It
didn't work out that way.  Since you have repeated your comments in other
forums (indeed you raise some new points), it is clear that our lack of
prompt response is not contributing to discussion and resolution of this
issue.

1) The XML Base specificiation results from the attempt by the XLink group
to fulfill it's requirements as found in the XLink Requirements Document.
During development, it was determined that supporting something equivalent
to the HTML BASE element was best provided generically to all uris, instead
of only those URIs which happened to be in xlink:href attributes. As a
generic layer, it was felt that a separate namespace (xml) and a separate
Working Draft would provide greater modularity.

2) XML Base was developed as a generic XML equivalent of html:base
functionality. But in generic XML, we can't expect all hyperlinks to be
represented as XLinks, neither do we expect URIs to appear only in
hyperlinks. We favored consistently addressing the base problem at the URI
level instead of the providing different base processing at the link level.

3) Layering XLink on top of XHTML, which in turn we hope will be layered
upon XLink, is a bit circular.

4) Scoping of xml:base supports XInclude, which originated in the XLink
group and is now being completed by the XML Core WG. Other applications
which move subtrees of XML around or merge them can make use of xml:base to
keep relative URIs from breaking with minimal intrusion into the document.
The scoping behavior of xml:space and xml:lang was used as a model.

Please accept my apologies.  I look foward to your response.

- Jonathan Marsh

> -----Original Message-----
> Date: Fri, 18 Feb 2000 03:26:45 +0800
> From: Rick JELLIFFE <ricko@gate.sinica.edu.tw>
> To: www-xml-linking-comments@w3.org
> Subject: Why is XBase needed?
> 
> I still cannot see why XBase is needed.
> 
> 1) For XML, we can use a entity reference.  XML Schemas are not
> replacing DTDs, because they operate on the infoset level not on the
> tokens: hence XML Schemas do take over from DTDs the entity 
> declaration mechanism or the ability to declare a default namespace 
> using a (e.g. #FIXED) attribute in a DTD.  So XBase cannot be 
> justified by any immanent disappearance of DTDs.  
> 
> So XBase duplicates an existing mechanism for XML documents, with the
> addition of some scoping of uncertain value.
> 
> 2) We already have an element defined with this functionality:
>   <html:base>
> If XLink does not need to create a new mechanism for dealing 
> with XHTML, it should merely recognise <html:base>. 
> 
> So a new attribute is not required for supporting html. 
> 
> 3) For XSL transformations, bases can just as easily be held in
> variables and generated in full in the output tree. 
> 
> 
> XBase looks like a uneeded complication, at a time when many 
> people want "simplicity".
> 
> I am particularly concerned that there seems to be no Requirements
> Document for it, since that would help me judge what on earth it is
> for.  I would hope there is no chance of anything going to Last Call
> without a Requirements Document first. 
> 
> 
> Rick Jelliffe
> 
> Academia Sinica Computing Centre
>

Received on Wednesday, 10 May 2000 12:38:53 UTC