Re: Revisiting namespaceDocument-8

[ The TAG has made progress since this message was originally posted,
  but I have had a long-standing action item to reply to it. ]

/ was heard to say:
| Norm:  Overall, this seems like a good direction.

Thanks :-)

| That said, one aspect of the namespace issue has been on my mind since we 
| "resolved" httpRange-14.  The paraphrase of that resolution is: "an 
| information resource can return HTTP 200 and representations; a non-info 
| resource should redirect, typically using 303".  So far so good.  If I 
| write a poem, I can give it an HTTP URI and serve up representations;  if 
| I want to give the poet himself an HTTP URI, then that must redirect using 
| 303 to a resource that is descriptive of the poet.

Or use a URI with a fragment identifier so that the URI of the
document and the URI of the poet are distinct. But I take your point.

| Now the questions about namespaces:  is a namespace an information 
| resource and therefore the sort of thing that can respond with a 200? 
| Certainly it's abstract in a way that the poet is not.  It has no mass and 
| won't knock you over if you run into it.   Web Arch characterizes an 
| information resource as  one for which  "all of their essential 
| characteristics can be conveyed in a message"[1] What are the essential 
| characteristics of a namespace, and can they be completely conveyed? 

As near as I can tell, a namespace is an intellectual construct that
can't possibly have any substance other than information. I'm no
philosopher, but I'm comfortable with the statement that a namespace
is an information resource.

| I note that seem to be abstractions that are not clearly information in 
| the Web arch sense.  Consider the concept of the "color red".  I might 
| want to make an rdf statement:
|         :noah :likes <>
| Can the essential characteristics of a color be conveyed in a message. 
| Does our httpRange-14 resolution allow a 200 status for 
|  If not, is a namespace this sort of 
| amorphous abstraction, or is it more specifically a collection of 
| information, presumably including at least the collection of names 
| qualified by a given URI?

There are intellectual constructs, like beauty, that have an
ineffeable quality. I don't know if "red" is ineffable or not. Quite
possibly, I think.

But I don't think namespaces fall into that category. I don't think
all abstracts are by nature ineffable.

| If we take the narrow interpretation that the namespace is in fact just 
| the set of qualified names, then it's not clear that the representations 
| we're proposing to return are in fact representations of the namespace. 

How so? If a namespace is just a set of qualified names then it would
seem to me that any document which enumerates the list of names (e.g. is manifestly a
representation of the namespace. If it gives additional information
(like pointers to schemas and stylesheets), that's a good thing. If it
gives less information (e.g., pointers to schemas and stylesheets but
w/o enumerating or describing the terms in the namespace), that may be
a low quality representation, but we're not responsible for the
quality of representations.

| They seem to be representations of a resource that is a description of the 
| namespace.  Isn't it exactly that distinction that caused us to argue for 
| a 303 in the case of the poet?

It doesn't seem that way to me. As I said, I can't think of anything
about a namespace that I couldn't communicate with a representation.
The same isn't true of physical constructs like the poet or ineffable

| As a practical matter, users are going to 
| be quite annoyed if we require that for every namespace they deploy a 
| server that uses a 303 redirect to get you to the RDDL, but I'm curious 
| what our theoretical justification is for allowing a 200 from the 
| namespace name. 

I hope I've explained why I think it's justified.

| Obviously, the last thing I'd advocate is a full reopening of 
| httpRange-14, but I do think it's worth convincing ourselves that the 
| resolution we've adopted can be applied consistently and conveniently to 
| the important case of namespaces and their descriptions.   If we stick 
| with our resolution of httpRange-14, then I think we need to be prepared 
| to set out what the information is that "comprises a namespace", so that 
| we can show that it can be "conveyed", or else we need to suggest use of 
| two URI's and a 303 for each namespace.

I don't think we need to do that. Users won't, even if we said they
should, so I think it would be best if we agreed that it wasn't
necessary :-)

                                        Be seeing you,

Norman.Walsh@Sun.COM / XML Standards Architect / Sun Microsystems, Inc.
NOTICE: This email message is for the sole use of the intended
recipient(s) and may contain confidential and privileged information.
Any unauthorized review, use, disclosure or distribution is prohibited.
If you are not the intended recipient, please contact the sender by
reply email and destroy all copies of the original message.

Received on Friday, 13 January 2006 19:52:16 UTC