- From: Chou, Wu (Wu) <wuchou@avaya.com>
- Date: Mon, 13 Apr 2009 14:21:36 -0400
- To: "Asir Vedamuthu" <asirveda@microsoft.com>
- Cc: <public-ws-resource-access@w3.org>, "Li, Li (Li)" <lli5@avaya.com>
- Message-ID: <F81BDFA28AE48D4793E253362D1F7A740112AB40@300813ANEX2.global.avaya.com>
It is a good idea to have a paper that explains how WS-MakeConnection (MC) composes with WS-Eventing and how it interworks with other WS-Addressing (WS-A)/WS-Eventing (WS-E) endpoints that do not support MC. We will also be interested to contribute to such a paper.
One particular question is: WS-A 1.0 Core specifies: "Comparison of [destination] property values is out of scope, other than using simple string comparison to detect whether the value is anonymous, that is, where [destination] has the value http://www.w3.org/2005/08/addressing/anonymous."
>From WS-A Core, it seems that some extension from WS-A implementation is needed in order to detect and understand the special MC anonymous EPR. If such extension is beyond the mandatory features of a WS-A endpoint, it would make sense to specify it as out-of-band to avoid additional requirements on a regular WS-A endpoint implementation.
The concern is: if the WS-A implementation cannot identify the special MC anonymous EPR by the simple string comparison as specified in WS-A 1.0 Core, it might treat the the special MC EPR as a regular EPR, and accept the event subscription to send events to it (MC anonymous EPR). If that happens, it could cause a major problem and the events won't be able to deliver.
To be concrete, assume there is an event source that understands WS-E and WS-A, but does not support MC. When the event subscriber sends a Subscribe message using the MC extension:
<wse:Subscribe>
<wse:Delivery>
<wse:NotifiyTo>
<wsa:Address>http://docs.oasis-open.org/ws-718 rx/wsmc/200702/anonymous?id=550e8400-e29b-11d4-a716-446655440000</wsa:Address>
</wse:NotifyTo>
</wse:Delivery>
</wse:Subscribe>
The event source checks the <wse:NotifyTo> EPR according to WS-A and decides it is neither "http://www.w3.org/2005/08/addressing/anonymous" nor "http://www.w3.org/2005/08/addressing/none" . Then it assumes it is an addressable EPR and will deliver notifications to it, which of course will fail.
This means using EPR alone to indicate MC style delivery will put an event source in one of the two situations:
1) The event source can be hit by a latent error because it does not recognize MC.
2) To avoid the latent error, the event source has to recognize the MC extension, even though it does not support MC.
- Wu Chou.
From: Asir Vedamuthu
Sent: Friday, April 10, 2009 5:00 PM
To: Christopher B Ferris
Cc: public-ws-resource-access@w3.org
Subject: RE: issue 6432 - yet another proposal
> Any event sink would be foolish to engage in MC interchange with
> an event source that did not advertise MC support in its policy.
Using WS-MakeConnection policy assertion to indicate the use of WS-MakeConnection protocol is possible. Earlier in the same mail thread [1], we mentioned that tiny subscribers are resource-challenged and may not have access to or may not understand metadata.
Anyway, such usages are outside the scope of WS-Eventing and should work with out-of-band agreements (and such agreements can be represented as a policy assertion).
Having said that, the Working Group should consider authoring a paper that explains how WS-MakeConnection composes with WS-Eventing using Doug's quoted sample as a starting point. We will be happy to help.
[1] http://lists.w3.org/Archives/Public/public-ws-resource-access/2009Apr/0027.html <http://lists.w3.org/Archives/Public/public-ws-resource-access/2009Apr/0027.html>
Regards,
Asir S Vedamuthu
Microsoft Corporation
From: Christopher B Ferris [mailto:chrisfer@us.ibm.com]
Sent: Thursday, April 09, 2009 6:32 AM
To: Asir Vedamuthu
Cc: public-ws-resource-access@w3.org
Subject: RE: issue 6432 - yet another proposal
Asir,
It says that comparison of destination properties is out of scope. It does not say that it is disallowed. The reason that that
statement is there is because URI comparison is non-trivial when you take into consideration all of the possible permutations
of encodings that might be used. Many specs have deferred to straight-forward string comparison as a means of side-stepping
the complexity.
As for your implied assertion that _all_ implementations need to understand MC, that is ludicrous. No one has suggested that, nor is it
necessary. Why do you think we spent all that time developing WS-Policy? MC has a policy assertion. Any event sink would be
foolish to engage in MC interchange with an event source that did not advertise MC support in its policy.
Cheers,
Christopher Ferris
IBM Distinguished Engineer, CTO Industry Standards
IBM Software Group, Standards Strategy
email: chrisfer@us.ibm.com
blog: http://www.ibm.com/developerworks/blogs/page/chrisferris <http://www.ibm.com/developerworks/blogs/page/chrisferris>
phone: +1 508 234 2986
From:
Asir Vedamuthu <asirveda@microsoft.com>
To:
Christopher B Ferris/Waltham/IBM@IBMUS, "public-ws-resource-access@w3.org" <public-ws-resource-access@w3.org>
Date:
04/08/2009 11:08 PM
Subject:
RE: issue 6432 - yet another proposal
________________________________
A WS-Addressing-aware implementation or library is NOT required to run character by character comparison to infer that a WS-MakeConnection extension is required to speak with an Event Sink.
"Comparison of [destination] property values is out of scope, other than using simple string comparison to detect whether the value is anonymous, that is, where [destination] has the value "http://www.w3.org/2005/08/addressing/anonymous <http://www.w3.org/2005/08/addressing/anonymous> "." [1]
An Endpoint Reference with encoded special semantics (WS-MakeConnection URI) ONLY makes sense IFF both sender and receiver understand the special semantics. This means, an Event Source (that is unaware of WS-MakeConnection) will not issue a fault that the Event Source does not understand the special semantics encoded in an Endpoint Reference.
What is the justification to require all WS-Eventing implementations to recognize WS-MakeConnection URI?
[1] http://www.w3.org/TR/2006/REC-ws-addr-core-20060509/#msgaddrpropsinfoset <http://www.w3.org/TR/2006/REC-ws-addr-core-20060509/#msgaddrpropsinfoset>
Regards,
Asir S Vedamuthu
Microsoft Corporation
From: public-ws-resource-access-request@w3.org [mailto:public-ws-resource-access-request@w3.org <mailto:public-ws-resource-access-request@w3.org> ] On Behalf Of Christopher B Ferris
Sent: Wednesday, April 08, 2009 1:29 PM
To: public-ws-resource-access@w3.org
Subject: Re: issue 6432 - yet another proposal
Jeff is correct. Opacity is not a quality of an URI. It is a principle: you should not infer anything from the
structure (or the content) of the path component of the URI. Note the use of the word "should" - I'll come back to that
later.
For instance, just because an URI ends in .pdf does NOT mean that the client/agent that uses that URI in a GET
should expect to receive an application/pdf media type in the response entity body.
So, repeat after me, opacity is not a quality, it is a principle. One URI is neither more, nor less "opaque" than another.
Period.
Now, what Asir may be alluding to is that the MC Anon URI is constructed from a URI template:
http://docs.oasis-open.org/ws-rx/wsmc/200702/anonymous?id= <http://docs.oasis-open.org/ws-rx/wsmc/200702/anonymous?id=> {unique-String}
Here's where the opacity principle can be ignored: when the URI authority provides explicit information as to how to
interpret the structure of the URI, as the WS-Make Connection spec [1] does. One can do a character for character
match of the string
http://docs.oasis-open.org/ws-rx/wsmc/200702/anonymous?id= <http://docs.oasis-open.org/ws-rx/wsmc/200702/anonymous?id=>
If it matches the first 58 characters of another URI, then that (other) URI is a MCanon URI.
I refer you to the TAG finding that specifies that such practice is just fine thank-you very much [2] (3nd bullet in conclusions section):
"* Assignment authorities may publish specifications detailing the structure and semantics of the URIs they assign. Other users of those URIs may use such specifications to infer information about resources identified by URI assigned by that authority."
[1] http://docs.oasis-open.org/ws-rx/wsmc/200702/wsmc-1.1-spec-os.html#_Toc162743905 <http://docs.oasis-open.org/ws-rx/wsmc/200702/wsmc-1.1-spec-os.html#_Toc162743905>
[2] http://www.w3.org/2001/tag/doc/metaDataInURI-31-20061204.html <http://www.w3.org/2001/tag/doc/metaDataInURI-31-20061204.html>
Cheers,
Christopher Ferris
IBM Distinguished Engineer, CTO Industry Standards
IBM Software Group, Standards Strategy
email: chrisfer@us.ibm.com
blog: http://www.ibm.com/developerworks/blogs/page/chrisferris <http://www.ibm.com/developerworks/blogs/page/chrisferris>
phone: +1 508 234 2986
From:
Jeff Mischkinsky <jeff.mischkinsky@oracle.com>
To:
Yves Lafon <ylafon@w3.org>
Cc:
Gilbert Pilz <gilbert.pilz@oracle.com>, Asir Vedamuthu <asirveda@microsoft.com>, Doug Davis/Raleigh/IBM@IBMUS, "public-ws-resource-access@w3.org" <public-ws-resource-access@w3.org>
Date:
04/08/2009 03:16 PM
Subject:
Re: issue 6432 - yet another proposal
Sent by:
public-ws-resource-access-request@w3.org
________________________________
hi,
My understanding of the use of "opaque" wrt to URI's is that you
are not supposed to infer anything from the structure of the URI, not
that specific uri's don't have specific "meanings"/semantics as
defined in specs.
Otherwise it is totally meaningless to define a uri and give it
semantics.
So this argument and asir's response don't make sense to me. You can
certainly tell that the 2 uri's in question are different and you can
certainly know what the semantics of using them are. So i don't see a
problem.
-jeff
On Apr 08, 2009, at 2:34 AM, Yves Lafon wrote:
> On Tue, 7 Apr 2009, Gilbert Pilz wrote:
>
>> WS-Addressing 1.0 - Core defines two "special" URIs;
>> "http://www.w3.org/2005/08/addressing/anonymous <http://www.w3.org/2005/08/addressing/anonymous> " and
>> "http://www.w3.org/2005/08/addressing/none <http://www.w3.org/2005/08/addressing/none> ". Messages targeted to
>> either
>> of these URIs are processed differently from messages targeted to
>> "normal" URIs such as "http://webserivce.bea.com/ <http://webserivce.bea.com/> . . .".
>
> Well, they are different, but unless you know WS-Addressing, or
> unless you resolve http://www.w3.org/2005/08/addressing/anonymous <http://www.w3.org/2005/08/addressing/anonymous>
> and find out the relationship between this URI and the WS-Addressing
> spec.
> If you resolve http://webservice.bea.com/.. <http://webservice.bea.com/> . you will probably have
> information about the endpoint, or you may know it in advance from
> another document. So both URIs are opaque, unless you know their
> semantic.
>
>
> --
> Baroula que barouleras, au tiéu toujou t'entourneras.
>
> ~~Yves
>
>
--
Jeff Mischkinsky jeff.mischkinsky@oracle.com
Director, Oracle Fusion Middleware +1(650)506-1975
and Web Services Standards 500 Oracle Parkway, M/S 2OP9
Oracle Redwood Shores, CA 94065
Received on Monday, 13 April 2009 18:22:26 UTC