Is it
worthwhile to distinguish the namespace URIs by adding "namespace" at the
front of the namespace URIs?
http://dita.oasis-open.org/namespace/
majorVersionIdentifier/nameCategory/namedThing
If
namespace URIs and schema URIs enter the same conversation, this would help to
keep them apart.
Bruce
Esrig
-----Original Message-----
From: Erik Hennum
[mailto:]
Sent: Tuesday, January 04, 2005 11:39
PM
To: Paul Grosso
Cc: DITA TC list
Subject:
Re: [dita] URIs and versions
Hi, Paul:
Good points. In addition to the identifying namespaces for
the document types,
we need the URI locations where the schema files can
be referenced.
What's the advantage of using "xml" instead of the more
explicit "dtd"
for the URI locations? I'd incline toward:
http://dita.oasis-open.org/schema/releaseIdentifier/schemaType/file
as
in:
http://dita.oasis-open.org/schema/1.0/dtd/concept.dtd
-
The DTD definition of the concept document type in the null namespace
for
the 1.0 release.
http://dita.oasis-open.org/schema/1.0/dtd/concept_ns.dtd
-
The DTD definition of the concept document type in the namespace of
the
concept document type for the 1.0 release.
http://dita.oasis-open.org/schema/latest/dtd/concept.dtd
-
The DTD definition of the concept document type in the null namespace
in
its most recent version (not necessarily the most recent
release).
...
http://dita.oasis-open.org/schema/1.0/xsd/concept.xsd
-
The Schema definition of the concept document type in the null
namespace
for the 1.0 release.
http://dita.oasis-open.org/schema/1.0/xsd/concept_ns.xsd
-
The Schema definition of the concept document type in the namespace
of the
concept document type for the 1.0 release.
http://dita.oasis-open.org/schema/latest/dtd/concept.xsd
-
The Schema definition of the concept document type in the null namespace
in
its most recent version (not necessarily the most recent
release).
...
On namespaces and versioning, it's true that
changing the namespace creates
an upgrade task. Conversely, isn't it
possible that keeping the same namespace
could cause processes to blow up
if they work with the old version of a document
type but not the new
version?
I would note that, because DITA provides a modular type
hierarchy, the
DITAArchVersion attribute indicates the version number only
of the architecture.
Document types could upgrade independently of each
other. Conversely, the
DITA architecture itself could in principle change
without changes to the
document types.
Some useful
references:
http://www.w3.org/TR/webarch/#ext-version
-
The Web Architecture requires a policy on versioning and namespaces but
doesn't dictate that policy.
http://www-106.ibm.com/developerworks/xml/library/x-tipnamsp.html
http://lists.xml.org/archives/xml-dev/200103/threads.html#00995
-
A summary and thread discussion of versioning and namespaces. The
compromise solution of a "latest" version would, I think, only work when
the
namespace resolves to the definition file, which is useful for schema
files
but not for an abstract document type that's implemented in multiple
schema languages. So, removing that option, the best practice
seems to
be to change the version identifier only for major upgrades.
It's
interesting that, in the draft Relax NG grammars for XHTML 2, the
namespace
remains the same as XHTML 1. That consistency might be
temporary -- I
didn't find any statement on the subject:
To sum up, I'd suggest a
convention like:
http://dita.oasis-open.org/majorVersionIdentifier/nameCategory/namedThing
where
majorVersionIdentifier is the year and nameCategory can
currently be
"architecture" for properties of the DITA architecture
"doctype" for
the document types that populate the architecture
and, in the future,
possibly "module" (or "topic" and "domain") for type modules
that populate
the architecture.
For example:
http://dita.oasis-open.org/2005/architecture/DITAArchVersion
http://dita.oasis-open.org/2005/doctype/concept
http://dita.oasis-open.org/2005/module/highlighting
(possible future)
The specification would note that the
OASIS TC will change the version identifier
only on major changes (or even
"incompatible changes"?) to the identified DITA
component.
Does that work?
Erik
Hennum
"Paul Grosso"
<> wrote on 01/04/2005 02:46:06 PM:
> I
didn't catch the exact details of our plans for
> URIs during the
telcon, but I do remember discussing
> getting the version info in
there.
>
> I remember related discussions in the W3C and
elsewhere,
> so I did some checking and talking to others.
>
> For organizing the various DTD and/or XML Schema modules
> and
shells and such, having the version as a step in the
> path usually
works well. It occurs to me that we might
> want to have both XML
Schemas and DTDs for DITA at some
> point. DocBook, which is in a
similar situation (and in
> fact also has SGML DTDs and RelaxNG
grammars) uses a
> scheme can be seen at http://docbook.org/xml/
> Our analogy
might be something like:
> http://dita.oasis-open.org/xml/1.0/the-various-modules-etc
>
The "xml" step--which implies XML DTDs--allows us later to
> have an
"xsd" subtree containing schemas and so forth.
>
> All the above
is about URIs for organizing the files,
> aka system
identifiers.
>
> As far as namespace names, there are problems
with putting
> the version into the namespace name. I'm not sure
if that
> was what was being discussed today or not, but if it
was,
> we might want to continue the discussion.
>
> If you
put the version into the namespace name, then you
> are putting all
your elements into a completely different
> vocabulary every version
which makes it very difficult to
> transition from one version to the
next. This practically
> guarantees serious legacy conversion
problems whenever one
> wants to transition to a new version. None
of your XSLT
> stylesheets that work with the old namespace will work
on
> any elements in the new namespace.
>
> Unless
we really want to enforce that "a topic in DITA 1.0"
> is a completely
different and incompatible object compared
> to "a topic in DITA 1.1",
then I don't think we want to have
> the version info in the namespace
name. Instead, applications
> that need to know the version of a
given bit of content should
> inspect the DTDArchVersion attribute
and/or some similar version
> attribute we may wish to add to all root
elements. But we should
> have a version-less namespace for DITA.
>
> This is somewhat analagous to the fact that all
XHTML--whether
> strict or loose and regardless of version--uses the
same
> http://www.w3.org/1999/xhtml namespace
name [1] so that a <p>
> element is always a <p> element
regardless of the details of
> the version of the document it's in.
(The "1999" is NOT any
> kind of version indicator--it is merely
the way the W3C doles
> out namespace names.)
>
>
paul
>
> [1] http://www.w3.org/TR/xhtml1/#normative
