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Re: NEW ISSUE: EPR comparison rule doesn't support Web services gateways/routers

From: Francisco Curbera <curbera@us.ibm.com>
Date: Tue, 25 Jan 2005 17:24:56 -0500
To: Mark Baker <distobj@acm.org>
Cc: public-ws-addressing@w3.org
Message-ID: <OFA1A1E20A.FCF06100-ON85256F94.007805A7-85256F94.007B228A@us.ibm.com>

This is the enterprise gateway scenario; the actual destination address is
of course not exposed, only the front end provided by the gateway. In this
case many services, or different (static or dynamic) configurations of the
same service are deployed behind the gateway. They can be exposed to
requesters by the gateway with different external addresses or with the
same; typically this is a deployment time decision, the former case being
more common probably. The concern is that it is not an uncommon situation
in real world enterprise deployments to use the same external address for
more than a single service/configuration, so it is not a great idea to put
those scenarios out of the scope.

This is a high cost for keeping in place a relic of the past like Section
2.3.

Paco




                                                                                                                                       
                      Mark Baker                                                                                                       
                      <distobj@acm.org>        To:       Francisco Curbera/Watson/IBM@IBMUS                                            
                                               cc:       public-ws-addressing@w3.org                                                   
                      01/25/2005 04:26         Subject:  Re: NEW ISSUE: EPR comparison rule doesn't support Web services               
                      PM                        gateways/routers                                                                       
                                                                                                                                       




Hi,

On Tue, Jan 25, 2005 at 02:28:53PM -0500, Francisco Curbera wrote:
> The text now states that two EPRs with the same URL and different ref.
> params. have the same metadata. This leaves out an important use case of
> Web service gateways/routers which is one of the most pervasive Web
> services products in the industry. In a gateway architecture we encounter
> situations where a single external address (http, smtp, message queue o
> whatever) front ends a variety of services deployed inside the
enterprise.

Do you mean URIs like http://backend.userland.com/rpc?  Or are you
referring to a fan-out style service where, for example, some RSS can be
POSTed to a URI, and it gets disseminated to a bunch of subscribers to
that URI?

If the latter, ok, but then the services at the other end would have
the same WSDL and the same policies, so that should be ok, right?

If the former, then I accept that this is done, but so are a lot of
other things that one would call "bad practice".  Specifically, if the
message was really intended to be sent to somewhere else down the line,
then that's where it should be addressed.  If this isn't a gateway
scenario, and instead an intermediary scenario, then routing could be
used to route to the intended destination via the intermediary.  Am I
missing something?

Mark.
--
Mark Baker.   Ottawa, Ontario, CANADA.        http://www.markbaker.ca
Received on Tuesday, 25 January 2005 22:25:30 GMT

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