Re: How could RDDL be distributed ?

[Michael Mealling <michael@bailey.dscga.com>]

On Tue, Jan 16, 2001 at 04:39:35PM +0000, Miles Sabin wrote:
> Michael Mealling wrote,
> > Since I'm helping write some of the RESCAP documents I might be
> > able to tweak them to do what you need. What do you
> > actually mean by distrubtion/replication? Is it the process
> > of populating the databases behind a particular RESCAP server?
> > Is it more along the lines of the "I have a local version of 
> > that XML Schema that I like better" problem?
> 
> The problem I want a solution to is,
> 
>   I have a public ID/system ID/URI for this DTD, external entity, 
>   schema, RDDL doc, etc.; find me a server which can give me an 
>   authoritative copy (in the case of a URI maybe a mirror of the 
>   main server).
> 
> or maybe rather than finding a server I just want the 
> authoritative copy itself.
> 
> So I guess it's more the former than the latter that I'm
> interested in, and yes, from my reading of the existing RESCAP
> docs it doesn't appear to address that problem.

Not in its entirety, no. The URI Resolution process is designed to
do just that. RESCAP is used in the final process to actually
ask the question your after. Here's the rought synopsis:


Given any URI you take the schem and append 'uri.arpa' to the end.
For HTTP you would end up with 'http.uri.arpa'. You lookup a NAPTR
record in DNS. This particular record allows you to do dynamic 
delegation by using regular expressions (see RFC 2915 for the
entire process). The output will then be a host, port, protocol, and
a set of services that are available at this network point. This
network end point will be authoritative for questions about that URI.
You then use one of the specified protocols to ask the question.
The questions can be as simple as "where is a copy of this" to
"where is a copy that has been authoritatively translated into 
Greek and in the Unicode character set" to "Is this URI an XML
namespace name?"

RESCAP is my recommendation for the protocol to use to ask that
final question. But it doesn't need to be the only one. I'm recommending
RESCAP because it's lightweight (one UDP out and one UDP back in most
cases) and fast. There is also a TLS spec so you can do any TLS
layer encryption/authentication.

-MM

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