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Re: The purpose of bindings

From: FABLET Youenn <youenn.fablet@crf.canon.fr>
Date: Wed, 21 Apr 2004 17:26:50 +0200
Message-ID: <408692BA.8020403@crf.canon.fr>
To: Jacek Kopecky <jacek.kopecky@systinet.com>
Cc: WS-Description WG <www-ws-desc@w3.org>

I think that if we are to add some text describing what to put in 
interfaces and what to put in bindings, we should also have some text 
explaining what to add at the service level. This would be especially 
useful if we allow features and properties at the service level.
I assume that the boundary is pretty loose in fact (for instance, the 
http version can be specified at the binding level, the use of https can 
be defined at the service level), but it would be good to have some 
guidelines and be consistent with them.
What do you think?

Jacek Kopecky wrote:

>Hi all,
>during yesterday's call we discovered it may be unclear what the purpose
>of bindings is, which makes very fuzzy the line of what should be in a
>binding and what should be in an interface.
>Here's my take:
>In WSDL, an Interface describes the application-level interface with all
>information necessary for the application. A Binding describes how the
>interface is realized on the wire.
>The main part of what the interface describes is the operations, message
>formats and exchange patterns. Additionally, using features (or
>extensions like policy or whatnot) an interface may specify other
>constraints, e.g. the necessity of authentication, confidentiality of
>communication, transactionality etc. Finally, an interface may describe
>important properties of operations and messages, e.g. web safeness or
>cacheability of results.
>A binding must be able to transfer the messages of its interface's
>operations, following the message exchange patterns, to an endpoint.
>Additionally, a binding must realize all features that an interface
>mandates and it must follow all constraints specified in the interface,
>e.g. the HTTP binding may realize communication confidentiality by
>mandating the use of HTTPS, or the SOAP binding may realize
>confidentiality by mandating the use of XML Encryption in the messages.
>Finally, a binding may take advantage of the properties described in its
>interface, for example by allowing opportunistic pre-invocation of
>web-safe operations or by allowing caching of cacheable results.
>To summarize, the boundary is in the application - information important
>for the application goes into interfaces, implementation details go into
>My on-line presence may be very sparse next week, so please be patient
>if any clarifications are necessary.
>Share and enjoy,
>                   Jacek Kopecky
>                   Systinet Corporation
>                   http://www.systinet.com/
Received on Wednesday, 21 April 2004 11:27:49 UTC

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