Agreed to defer introduction of URNs to
DFDL vNext due to problems that XML tools would experience if both allowed.
Regards
Steve Hanson
Architect, Data Format Description Language (DFDL)
Co-Chair, OGF
DFDL Working Group
IBM SWG, Hursley, UK smh@uk.ibm.com
tel:+44-1962-815848
From:
Mike Beckerle <mbeckerle.dfdl@gmail.com>
To:
Steve Hanson/UK/IBM@IBMGB,
Cc:
Suman Kalia <kalia@ca.ibm.com>,
dfdl-wg@ogf.org, dfdl-wg-bounces@ogf.org
Date:
19/11/2012 21:33
Subject:
Action 192:
URN scheme - was: Re: [DFDL-WG] new action item needed: DFDL URN specification
I'd like to add a sub-space for implementations to use
for their implementation-specific things. Nice thing about a URN is that
it can specify a structured scheme for this:
I suggest "imp" as a sub-specifier for implementation-specific
URNs. E.g., urn:ogf:dfdl:2011:imp:...
What goes after imp is an identifier of an implementation. E.g.,
and beneath that is anything that implementation needs/wants. E.g., a namespace
for extension properties that are non-standard, a version ID for sub-versions
of that implementation, etc. etc.
This allows an implementation to define extension properties, and have
other implementations give warnings that those are detected, but not understood.
...mikeb
On Mon, Oct 29, 2012 at 11:37 AM, Steve Hanson <smh@uk.ibm.com>
wrote:
Using the OGF's URN registration document
[GFD.191] as a reference, I suggest:
I tend to agree that specifying urn for namespaces is better choice
and URL should be used for schema locations; however convention
of specifying URL for namespaces is long established some implementations
use the namespace URL to return the actual schema.
When I try to access the namespace URL for XML schema , it gives me reference
to the document but not schema..
Suman Kalia
IBM Canada Lab
WMB Toolkit Architect and Development Lead
Tel: 905-413-3923
T/L 313-3923
Email: kalia@ca.ibm.com
I wanted to add to this discussion the w3c blog page that highlights the
problem of the http-based naming scheme. There are many articles about
this, this is just one of them.
W3C has badly regretted establishing this convention, as they have farms
of servers that do nothing but quickly return 404 errors to save network-aware
applications the network-timeout delay that would otherwise occur.
There are parties interested in exploiting DFDL who want DFDL schemas to
NOT contain network URLs because it simply creates a concern about network
access whenever a DFDL schema is inspected/used.
Pre-Proposal:
The new way to do this is with URNs which would look roughly like this:
urn:ogf:dfdl:standard:dfdl-1.0. The whole point is that some other mechanism
is used to establish correspondences between these and any resources in
file systems, networks, or built-in to implementations. One such mechanism
is called XML Catalog.
The point is that it is a name in a managed namespace which cannot be confused
with a network protocol URL.
OGF is already establishing urn:ogf, and an ogf subgroup has already proposed
urn:ogf:network for network resources. DFDL schemas aren't network resources
so we don't want to be a substructure underneath network.
Some other mechanism is used to establish correspondences between these
and any resources in file systems, networks, or built-in to implementations.
One such mechanism is called XML Catalog.
Summary:
An action item should be to specify DFDL urn, submit to OGF as a proposed
namespace, and then produce errata/spec changes to specify its use.
This requires a small design activity to specify a scheme for the sub-structure
of the DFDL URNs (i.e., scheme for the stuff after urn:ogf:dfdl:...) where
we want standard identifiers for versions of the standard, but we probably
also want a few other things (e.g., I would like a space for implementations
to identify themselves, i.e., an implementation-specific sub-area within
our URNs.)
Our existing URLs can be compatible (deprecated) practice vs the preferred
URNs.
--
Mike Beckerle | OGF DFDL WG Co-Chair
Tel: 781-330-0412
Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number
741598.
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6
3AU
--
Mike Beckerle | OGF DFDL WG Co-Chair
Tel: 781-330-0412
Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number
741598.
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6
3AU