Re: URI resolver was Re: RDDL and XML Schemas Proposed Recommendation

[Justin Couch <justin@vlc.com.au>]

Jonathan Borden wrote:

> I think unfortunately there exists alot of confusion around the whole area
> of URIs, what they 'mean', what they do in practice and what they are
> intended for. 

Hmm. Interesting. Considering a lot of the work I did on early URI
implementation was driven by what Tim et al were talking about waaaay
back when with HTML 1.0 etc. ie The URI concept came first and then
"restricted" to the more immediately useful URL. Then, started working
over in the IETF realm and a lot of the concepts seemed to match quite
nicely. Somewhere in between it seems that the path has diverged. Why,
I'm not sure, but someone else is pointing this out, not me. I think my
definitions are The One True Definition :)

> Like in many/most endeavors, different people and groups develop different
> implementations aimed at solving similar problems. Michael et al. have been
> working at one end of the issue, and I've had the opportunity to read
> through a few of the _experimental_ RFCs (e.g. 2169,2483) and I see how
> Michael and Justin are using the term "URI resolution".

Aye, That's because we've been implementing the darn things :)
 
> My original question was in reference to issues regarding namespaces: How
> can I determine when two namespace URIs can be used interchangably? How can
> I determine when one namespace URI is intended to "replace" another? These,
> I _think_, are practical questions without definitive answers.

I think that is a hard question to answer because it doesn't really ask
anything. Without knowing what you want to "resolve" how can you define
that something is equivalent. Micheal and I gave our answers based on
what we believe normal URI systems should provide as we work with URIs
and URI systems on a daily basis. The answer I'm hearing is "that's not
what we defined URI to be" without actually giving something concrete as
an example of what is meant. We can tell you how to answer that question
our way, but if that is not the way wished, then we can't provide any
further help.

Where further clarifications are going to be needed are when other
specifications start using the term. VRML 2.0 has used it for the last 3
years and now we are starting to get VRML 3.0 in XML format. Suddenly we
have two different ideas of what a "URI" is expressed within the same
document so someone had better come up with answers real quick because
one community will end up bashing the other one over the head because of
their "incorrect" usage of the term. Of course, the X3D work becomes
even more interesting because the Web3D consortium is a standards feeder
to W3C....

> been working with the same issues in 'examplotron', has requested and I have
> added a new RDDL purpose to assist with this.

Well, if I get a chance in about a week's time, I'll have a look at the
codebase. If possible, I'll try to wedge in my URI resolver library to
do some of this stuff, just to see what the impact of combinin these two
worldviews are. Will it create problems, or is just a case of people
reading the same text but speaking different dialects of the same
language?

-- 
Justin Couch                         http://www.vlc.com.au/~justin/
Freelance Java Consultant                  http://www.yumetech.com/
Author, Java 3D FAQ Maintainer                  http://www.j3d.org/
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