RE: [xml-dev] Namespaces - a couple nits and questions

["Chris Wilper" <cwilper@cs.cornell.edu>]

Hi Danny,

Here are my opinions on 3 and 4.

3) There *should* be a unique identifier for a format[1] but namespace 
   identification is different than format identification.  It doesn't
   stop people[2] from assuming they're the same, though.  Of all the
   questions you brought up, this is the one I think is most important.
   Resist the temptation to merge these concepts.  They seem friendly
   enough toward each other, but down the road they won't play nice.
   Why, I saw namespace running with scissors just last week.

4) The best way to do this, IMHO, is to have your namespace identifiers
   use a URI scheme that ties it to an organization.  Namely, yours.
   And you're right in thinking it's a good idea to "own" your namespace.
   Of course there's no way to enforce that[3].
   On the subject of what URI scheme to use:  Personally I use http: 
   because I like RDDL and the knowledge that descriptions of my namespace 
   could be retrieved if some agent/person wanted to.  There's debate about the 
   use of URL URIs for identifiers, though.  My priority is accessibility 
   of specs/documentation, and I know if I use http, even the simplest of 
   agents could get at it.

Good luck,
Chris

[1] Something analogous to what I'm calling "streamforms".  See
    http://lists.xml.org/archives/xml-dev/200210/msg00717.html and
    http://lists.xml.org/archives/xml-dev/200210/msg01397.html
[2] http://msdn.microsoft.com/library/en-us/dnglobspec/html/draft-nielsen-dime-02.txt
[3] Although... my fiance used to work at Target... and she said they're trying 
    to own the color red, so maybe there's some kind of definitive concept 
    ownership registry out there...hmmm...check IANA.

-----Original Message-----
From: Danny Vint [mailto:dvint@mindspring.com]
Sent: Monday, October 28, 2002 1:47 PM
To: xml-dev@lists.xml.org
Subject: [xml-dev] Namespaces - a couple nits and questions


My organization is starting to apply namespaces to its various specs. I 
know the general discussion and likes/dislikes about them, but I don't 
think I have seen anyone address them from the following viewpoint, so I'd 
be interested in some discussion.

There seem to be the following views or ways to use a namespace:

1) Original spec seems to see them as a way to disambiguate two elements 
with the same name - plain and simple no semantics or other 
overhead/overloading of their use.

2) In schemas, they with some of the attributes in <Import> seem to handle 
the same functionality of the DOCTYPE and its PUBLIC and SYSTEM identifiers.

3) Coming from the OO world seems to be the notion of domains for 
vocabularies. We have a banking domain, an insurance domain, a 
manufacturing domain, and legal domain. The element <title> might be used 
in all of these domains, but I should identify the domain that it comes 
from by using the proper namespace to identify its definition.

4) A namespace as a owned resource that should be protected from other 
groups and organizations stepping on it. This came up in regards to use of 
<redefine> to add or enhance my organizations definitions with company 
unique information or requirements.

I work for ACORD an Insurance industry standards group and when we had a 
general meeting on namespace usage all of the above definitions and uses 
were brought up. I personally think at least #3 is a different sort of use 
for namespaces when we need to answer the following questions, and that #4 
is a rather restrictive way to view their use when trying to extend a 
specification.

Questions:

Q1) I have 3 different standards within our organization and they may have 
the same elements and some of the same structures. How should namespaces be 
used to identify these particular standards? Should I have one Insurance 
domain namespace?

Our standards are currently divided along the lines of Life, Property, 
Causality and Surety, and Reinsurance, should I have different namespace 
for each? At least one of these specs has been split into 2 parts, one 
being the payload (business/Insurance data) and the other being a framework 
or messaging structure that includes the payload portion.

Should this be all one namespace or should they be at least 2 namespaces? 
Should the included portion be identifiable by 2 namespaces (one namespace 
being when used standalone and the other when used in the message structure)?

Q2) Should a namespace be versioned? This is more for file and element 
identification which fits #1 and #2, but seems contrary to #3.

Q3) Should a namespace act like a PUBLIC Identifier and be able to identify 
a specific file and version of a schema (lets ignore DTDs for now)? This 
doesn't mean that I would be able to look up the URL and find the schema, 
but that there should be a unique name/namespace for each version.

Q4) Should my organization be "protecting" our namespace and make sure that 
no one <redefine>'s that namespace to be something unique for them?

..dan
---------------------------------------------------------------------------
Danny Vint
http://www.dvint.com


     


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