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Re: i0001: EPRs as identifiers - alternative proposal

From: Francisco Curbera <curbera@us.ibm.com>
Date: Thu, 2 Dec 2004 11:08:51 -0500
To: Mark Baker <distobj@acm.org>
Cc: public-ws-addressing@w3.org, public-ws-addressing-request@w3.org
Message-ID: <OF8292B5E8.383E1927-ON85256F5E.005810FF-85256F5E.0058B31E@us.ibm.com>

Mark,

I think that the argument (in your referenced mail below) that addresses
are some form of identifiers is rather weak. Alternatively, it is a strong
argument claiming that addresses are very weak identifiers :-) Architecting
systems on the assumption that you may identify resources with an address
is a recipe for disaster. The idea that network endpoints can be provided
URI identifiers is a different matter; my opinion is only that runtime
service endpoint addresses should not be constrained to be URIs (although
some may want to do just that).

Paco



                                                                                                                                               
                      Mark Baker                                                                                                               
                      <distobj@acm.org>               To:       Francisco Curbera/Watson/IBM@IBMUS                                             
                      Sent by:                        cc:       public-ws-addressing@w3.org                                                    
                      public-ws-addressing-req        Subject:  Re: i0001: EPRs as identifiers - alternative proposal                          
                      uest@w3.org                                                                                                              
                                                                                                                                               
                                                                                                                                               
                      12/02/2004 12:05 AM                                                                                                      
                                                                                                                                               





Hey,

On Wed, Dec 01, 2004 at 01:00:27PM -0500, Francisco Curbera wrote:
> Rationale
> =======
>
> EPRs are not identifiers, only addresses. Let me explain.

FWIW, after the RefProps/RefParams discussion, I now agree that EPRs
are not necessarily identifiers.  But I don't see them as addresses
either, since addresses are identifiers[1].

IMO, the best way to think of this is with the EPR as a 2-tuple with an
identifier and some contextual state, in exactly the same way we think
of http URIs and cookies.  So, I believe that an EPR is an identifier
iff it contains no contextual state, i.e. no RefParams.

> One remaining question is whether EPR (as addresses) should be URIs but I
> think this should be opened as a separate issue.

I disagree.  I think it's part and parcel.  But no biggie, as long as it
gets its day in court. 8-)

So unfortunately, I'm -1 on the proposal.  And I'd consider writing up
my own proposal, but it involves removing RefProps (to provide a single
identifying data element), and I don't see that flying just yet.  But
we'll see where DavidB and Hugo get on that front ...

 [1]
http://lists.w3.org/Archives/Public/public-ws-addressing/2004Nov/0588.html

Mark.
--
Mark Baker.   Ottawa, Ontario, CANADA.        http://www.markbaker.ca
Received on Thursday, 2 December 2004 16:09:23 GMT

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