Comments on: A new Namespaces discussion

By: Tom in Cala Dor Palma de Mallorca

Tom in Cala Dor Palma de Mallorca — Sun, 01 Oct 2006 11:16:33 +0000

I can see Eliot’s point of view, since as he himself notes, he is a system integrator. I’m sure he’s suffered through many schemas from different sources which uses the same element/attribute names for different things, exactly what namespaces can help fix. That said, it doesn’t mean that every little XML document needs to be namespaced, if it remains private enough.

By: Laender

Laender — Tue, 02 May 2006 21:30:16 +0000

Thanks Ed, thats (http://norman.walsh.name/2004/11/10/xml20) a really good site!

By: Eric van der Vlist

Eric van der Vlist — Tue, 28 Feb 2006 10:19:21 +0000

David,

The general issue of QNames in content is one of the windmills against which I have been fighting with limited success. My main success has been to get alternatives to QNames in content for RELAX NG and Schematron but I am not sure I have been able to really convince James Clark about this point…

The issue you mention regarding the dependency between XPath expressions and their context isn’t new and, as far as I recall, it has been the reason why XPointer has been brought back from CR to Last Call in early 2001!

See http://www.xmlhack.com/read.php?item=982 .

Eric

By: John Watson

John Watson — Mon, 27 Feb 2006 11:04:42 +0000

I think the ‘QNames in XPath expressions’ problem weakens various important XML specs. For example XUpdate seems to be unable to update target documents that use namespaces. I imagine it’s for this reason. At any rate the spec has no mention of how to incorporate a namespace prefix from the target document into an XPath expression in the update.

By: Ed Davies

Ed Davies — Sun, 26 Feb 2006 23:59:10 +0000

Norman Walsh has a proposal:

http://norman.walsh.name/2004/11/10/xml20

for “XML 2.0″ which would fix the QNames in content problem pretty neatly, I think.

By: Anthony B. Coates

Anthony B. Coates — Sun, 26 Feb 2006 22:56:39 +0000

As for XPath, I consider the difficulties in the use namespaces with XPath to be a weakness in XPath, one that causes me a regular amount of pain. I don’t consider it a weakness in the way XML does namespaces. XPath is a convenient nuisance at any time; it’s text format is short and convenient, but the fact that it’s text and not XML sometimes makes it inconvenient. Not having anywhere to put namespace declarations is one side effect of the textual format. Still, would it be *so* hard to provide an extra parameter somewhere to allow the namespaces to be specified?

With XSLT, it becomes a nuisance that there isn’t an easy way to pass the namespace prefix to URI mappings into a script. If you could, it would certainly make XSLT transformations more robust with respect to namespace URI changes.

Cheers, Tony.

By: Lars Marius Garshol

Lars Marius Garshol — Sun, 26 Feb 2006 17:08:14 +0000

The problem with QNames in queries is also faced by the RDF and Topic Maps query languages, all of which solve it by allowing the developer to declare prefixes inside the query. That would work for XPath, too, but the downside is that since XPath “queries” tend to be so short, the prefixes would be disproportionately long. Still, if you really want self-contained queries, I can’t really think of any other way.

By: david

david — Sun, 26 Feb 2006 17:02:38 +0000

Eliot referred to it in his posting — earlier drafts of the Namespaces spec used processing instructions for declarations, but we switched to attributes. It seems pretty trivial in retrospect, but at the time, we’d wanted to keep the element/attribute/content tree clean (i.e. you wouldn’t have declarations and real attributes mixed together).

By: Joe English

Joe English — Sun, 26 Feb 2006 15:53:09 +0000

Curious — what was the major change in the spec alluded to in the first paragraph? (I have a hunch where it came from, but wasn’t in on the process so it’s just a hunch).

Wholeheartedly and vigorously agree about QNames-in-content — these are bad, bad, bad.