Re: URIs for RDDLs, WSDLs, Schemas, etc

[Robin Cover <robin@oasis-open.org>]

Thanks, Alex.

Alas, I have not been fast enough in my communications.

The example provided from the existing implementation of
WS-RX TC NS URIs is not a good example.  It represents the
state of affairs as initially requested by the WS-RX TC,
but in subsequent conversations with the (relevant)
TC members, it was admitted/agreed that the OASIS
implementation at the server level

a) using special hand-crafted index files
b) with META refresh redirects
c) which brings the RDDL document URI into the browser adddress
   window when the NS URI is dereferenced

is neither desirable nor optimal.

Hence, my message of earlier today:

   Subject: URIs for RDDLs, WSDLs, Schemas, etc
   Message-ID: <Pine.LNX.4.58.0608161358580.6632@dev.oasis-open.org>

urged your TC to consider a different strategy which does NOT
locate the schema files in the proposed directories -- since the
NS URI is in effect overloaded.

If you want to follow the example used (currently) for the WS-RX
TC, that's OK, but please realize:

a) we cannot recommend that solution as optimal or desirable
b) we intend to fix the implementation in the WS-RX TC as soon as
   we get OASIS IT support -- viz., it will then NOT work
   in the manner you now observe
c) we intend to fix a couple related implementations that use the
   (crude, kludge, hack META refresh redirect mechanism)
d) the ebxml-bp TC members initially requested an implementation of
   the NOT-recommended type, and we are in the midst of a
   painful process to correct that situation by reduplicating
   files to a new directory where they can be listed using
   standard/default Apache indexing

So you say:

"If the pattern is feasible for WS-RX, it should work for us also."

to which I need to reply:  "the WS-RX TC pattern is not a good
implementation pattern to follow," even if it's "feasible"
in the sense of being nominally functional.

I am very proud of the pioneering work done on RDDLs by Marc
Goodner, Chris Ferris, Paul Cotton, and others in the WS-RX
TC.  Unfortunately, we were unable to provide an optimal
implementation at the server level.  We are trying to avoid
further problems by asking TCs to consider an alternate
pattern for schema location.  The server implementation
(I would characterize as a crude hack) is not something
the WS-RX members envisioned or requested: it is the
temporary solution provided by OASIS staff.

In any case, when OASIS IT provides the requested support
for Apache redirects, we will continue to deliver a (RDDL)
namespace document when the namespace URI is dereferenced.
However, the implementation will be a lot cleaner, and will
avoid some of the (reported) DNS/HTTP resolution problems
associated with the current implementation.  Using
the appropriate Apache directives will also allow us to
override the default Apache redirect problem described in
my note earlier today.

I apologize that I was unable to dive into this discussion
earlier.

Thanks.

Robin Cover

On Wed, 16 Aug 2006, Alex Yiu wrote:

>
> Hi Robin,
> (cc'ing Prasad and wsbpel-spec-editing list)
>
>
> Thanks for your email.
>
> Robin wrote:
>
> >a) Directory URI: http://docs.oasis-open.org/wsbpel/2.0/process/abstract/
> >b) NS URI: http://docs.oasis-open.org/wsbpel/2.0/process/abstract
> >
> >The current default server behavior is to issue a redirect from "b)" to "a)" when a user (agent) requests the resource at "b)".  This default handling makes it impossible to produce a (raw, Apache-generated) directory listing for the contents of the "abstract" directory because dereferencing the NS URI needs to produce the associated RDDL namespace document. Given our existing limitations, there's no way to get Apache to list the directory contents, because the URI is overloaded.
> >
> >
>
> Not being able to produce a (raw, Apache-generated) directory listing is
> fine to me. We don't need a raw directory listen, if we got a XHTML+RDDL
> document already. That document is a better way to explain the content
> of that directory.
>
> Let me re-iterate my viewpoint so far by lookin into Mary's WS-RX example:
>
> schema location =
> http://docs.oasis-open.org/ws-rx/wsrm/200510/wsrm-1.1-schema-200510.xsd
> targetNamespace =
> "http://docs.oasis-open.org/ws-rx/wsrm/200510";
>
> When people try to use a brower (user-agent) to access
> "http://docs.oasis-open.org/ws-rx/wsrm/200510"; or
> "http://docs.oasis-open.org/ws-rx/wsrm/200510/";
> it will be redirected to the landing page with RDDL:
> "http://docs.oasis-open.org/ws-rx/wsrm/200510/wsrm-1.1-rddl-cd-02.html";
>
> The above pattern fits our need also in general.
>
> If the pattern is feasible for WS-RX, it should work for us also.
>
> We just need SIX landing-page (XHTML+RDDL) with the following location:
>
> One for the top level:
> http://docs.oasis-open.org/wsbpel/2.0
>
> Five for 5 XSD:
> http://docs.oasis-open.org/wsbpel/2.0/process/abstract
> http://docs.oasis-open.org/wsbpel/2.0/process/executable
> http://docs.oasis-open.org/wsbpel/2.0/plnktype
> http://docs.oasis-open.org/wsbpel/2.0/serviceref
> http://docs.oasis-open.org/wsbpel/2.0/varprop
>
>
> What do you guys think?
>
>
>
> Thanks!
>
>
>
> Regards,
> Alex Yiu
>
>
>
>
> Robin Cover wrote:
>
> >Alex (and others),
> >
> >Based upon a posting of 14 Aug 2006 [1] and subsequent
> >off-list email messages, I understand that the five
> >namespace URIs are to be:
> >
> >http://docs.oasis-open.org/wsbpel/2.0/process/abstract
> >http://docs.oasis-open.org/wsbpel/2.0/process/executable
> >http://docs.oasis-open.org/wsbpel/2.0/plnktype
> >http://docs.oasis-open.org/wsbpel/2.0/serviceref
> >http://docs.oasis-open.org/wsbpel/2.0/varprop
> >
> >I see no problems at all with these namespace URIs.
> >
> >The posting from 14 Aug 2006 also identifies five
> >corresponding schema location URIs, which (adjusted for
> >the ws-bpel -->> wsbpel change) would be:
> >
> >http://docs.oasis-open.org/wsbpel/2.0/process/abstract/wsbpel_abstract_common_base.xsd
> >http://docs.oasis-open.org/wsbpel/2.0/process/executable/wsbpel_executable.xsd
> >http://docs.oasis-open.org/wsbpel/2.0/plnktype/wsbpel_plnktype.xsd
> >http://docs.oasis-open.org/wsbpel/2.0/serviceref/wsbpel_serviceref.xsd
> >http://docs.oasis-open.org/wsbpel/2.0/varprop/wsbpel_varprop.xsd
> >
> >If the TC wants to insist on these URIs, I believe the OASIS
> >IT Staff can adjust to that decision, and provide normal
> >but minimal server support for the resources represented by
> >the five files at the implied file system locations.
> >
> >However, for consistency in OASIS operations, it would be
> >preferable NOT to store the schemas in the file system
> >locations implied by the URIs above, but rather, to store them
> >in a separate directory. For example, the five schemas
> >could be stored in a directory /schemas/, resulting in this
> >set of URIs:
> >
> >http://docs.oasis-open.org/wsbpel/2.0/schemas/wsbpel_abstract_common_base.xsd
> >http://docs.oasis-open.org/wsbpel/2.0/schemas/wsbpel_executable.xsd
> >http://docs.oasis-open.org/wsbpel/2.0/schemas/wsbpel_plnktype.xsd
> >http://docs.oasis-open.org/wsbpel/2.0/schemas/wsbpel_serviceref.xsd
> >http://docs.oasis-open.org/wsbpel/2.0/schemas/wsbpel_varprop.xsd
> >
> >Let me explain why this would be preferable from the OASIS
> >point of view.
> >
> >At the current time, the OASIS servers associated with the Internet
> >domains www.oasis-open and docs.oasis-open.org use configurations
> >which are interdependent, and are tuned to reflect different needs
> >in Kavi and non-Kavi resources. That means the IT programming team
> >cannot, at this time, provide the ideal form of support for
> >server behavior when an HTTP scheme URI is dereferenced. For example,
> >at this time if the following namespace URI is to be supported,
> >
> >   http://docs.oasis-open.org/wsbpel/2.0/process/abstract
> >
> >we would create a directory "abstract" beneath the directory
> >"process", yielding the following two URIs:
> >
> >a) Directory URI: http://docs.oasis-open.org/wsbpel/2.0/process/abstract/
> >b) NS URI: http://docs.oasis-open.org/wsbpel/2.0/process/abstract
> >
> >The current default server behavior is to issue a redirect from "b)"
> >to "a)" when a user (agent) requests the resource at "b)".  This
> >default handling makes it impossible to produce a (raw, Apache-
> >generated) directory listing for the contents of the "abstract"
> >directory because dereferencing the NS URI needs to produce the
> >associated RDDL namespace document. Given our existing limitations,
> >there's no way to get Apache to list the directory contents,
> >because the URI is overloaded.
> >
> >I must clarify that under ideal conditions, server configuration
> >tools should allow the IT programming team to implement some
> >"non-default" server behavior using Apache directives (e.g.,
> >mod_rewrite, mod_alias, mod_dir ) which would avoid the
> >redirect from "b)" to "a)" and so forth. [2]
> >
> >For these reasons, and for some broad concerns for usability in
> >our OASIS context (desire for transparent access to the web
> >server's file system), it's better not to store content (files,
> >directories, symlinks, etc) in directories matching these URIs:
> >
> >http://docs.oasis-open.org/wsbpel/2.0/process/abstract/
> >http://docs.oasis-open.org/wsbpel/2.0/process/executable/
> >http://docs.oasis-open.org/wsbpel/2.0/plnktype/
> >http://docs.oasis-open.org/wsbpel/2.0/serviceref/
> >http://docs.oasis-open.org/wsbpel/2.0/varprop/
> >
> >If the specification includes WSDL files, RDDL files, and
> >perhaps other files associated with the prose document(s)
> >and XML schemas. it would be better to store those files
> >(WSDLs, RDDLs, XML schemas) in one or more separate
> >directories other than in the five referenced immediately
> >above.
> >
> >We can arrange a phone call to discuss details further, if
> >that might prove useful.  I would also like to see the complete
> >listing of files associated with version 2.0 of the Web
> >Services Business Process Execution Language spec.
> >
> >Robin Cover
> >
> >PS  You may forward this message to anyone on the design/editorial
> >team.
> >
> >[1] http://lists.oasis-open.org/archives/wsbpel/200608/msg00051.html
> >    Subject: Issue - 289 - Proposal to vote
> >    * From: Alex Yiu <alex.yiu@oracle.com>
> >    * To: wsbpeltc <wsbpel@lists.oasis-open.org>
> >    * Date: Mon, 14 Aug 2006 13:25:18 -0700
> >
> >[2] Apache modules
> >
> >http://httpd.apache.org/docs/2.0/mod/mod_rewrite.html
> >http://httpd.apache.org/docs/2.0/mod/mod_alias.html
> >http://httpd.apache.org/docs/2.0/mod/mod_dir.html
> >
> >
> >
>
>