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   Re: [xml-dev] XML Base (RE: [xml-dev] Article: Keeping pace with James C

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> Elliotte Rusty Harold wrote:
> > Only xml:base could arguably 
> > be claimed to be at the semantic level, and even that is less 
> > semantic than xml:lang.
> I think it's time to take a long hard look at XML Base and question
> whether this spec:
> a) is useful
> b) is necessary
> c) belongs in the "XML Core"
> On (a), I think XML Base is useful for people too lazy to type complete
> URIs.  Why exactly those people are typing their XML directly (i.e.
> there's no app to fill in their URIs for them) when they're that lazy is
> beyond me.  For these people XML Base ensures that they don't have to
> worry about moving documents from point A to point B and having all the
> links break.  They can also save a few bytes of redundant information,
> though again why they'd be concerned about that when they're using XML
> is beyond me.

I think it's ridiculously harsh to characterize XML:Base as useful only for 
people who are too lazy to type URIs.  XML Base is a handy tool for solving a 
particular class of problems involving interpretation of relative URIs in 

One possible solution for this is to eliminate the allowance of relative URIs 
in content.  Not that I agree with this, but as long as relative URIs are 
allowed in content, XML Base will be useful for solving real problems that 
have nothing to do with laziness.

> On (b), I think the answer is quite plainly NO. XML Base is never
> necessary.  You can always type out URIs, and you can even do a
> search-and-replace if necessary.

Well lots of things in XML are never necessary.  How about 
(non-character-reference) entities?  How about comments?  processing 
instructions?  I don't argue getting rid of these (and the many other such 
things I didn't mention) myself.

Of course, sometimes you do have to draw the line: the PSVI, for instance, 
gives me a red mist before my eyes largely because of its complexity.  If it 
were as simple as XML Base, I could probably live with my fundamental 
disagreement with it.

> On (c), I think we have some enormous problems.  XML Base by itself
> provides a base URI, but it's up to the application to figure out how to
> use that information.

Yes.  And some applications are: RDF, XSLT and XLink.  I don't see the problem 
with this.

> The XML Infoset prescribes no particular handling
> for this information or combination with URIs, and the XML Base
> specification itself states that:
> --------------------------------------
> The deployment of XML Base is through normative reference by new
> specifications, for example XLink and the XML Infoset. Applications and
> specifications built upon these new technologies will natively support
> XML Base. The behavior of xml:base attributes in applications based on
> specifications that do not have direct or indirect normative reference
> to XML Base is undefined.
>  --------------------------------------
> The Infoset has some fine language about "computed according to [XML
> Base]", but it's hardly clear how this metadata is to be applied - or
> represented, in the case of document fragmentation, for instance.

This sounds like a case were the Infoset needs to be clarified.

> It would be nice to keep such frivolous bits out of the XML Core, I
> think.

It's certainly possible that you're right, but personally, I'm not yet 

Uche Ogbuji                                    Fourthought, Inc.
http://uche.ogbuji.net    http://4Suite.org    http://fourthought.com
Track chair, XML/Web Services One Boston: http://www.xmlconference.com/
The many heads of XML modeling - http://adtmag.com/article.asp?id=6393
Will XML live up to its promise? - http://www-106.ibm.com/developerworks/xml/li


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