W3C home > Mailing lists > Public > www-ws-desc@w3.org > January 2004

Alternate approach to indicating operation styles

From: Jacek Kopecky <jacek.kopecky@systinet.com>
Date: Mon, 19 Jan 2004 10:37:01 +0100
To: WS-Description WG <www-ws-desc@w3.org>
Message-Id: <1074505020.1966.49.camel@localhost>

Hi,

discharging my action item I'm here proposing an alternate approach to
indicating operation styles (not using the 'style' attribute).

We've adopted the idea of operation styles to allow indicating that an
operation follows a set of constraints that makes it (more) suitable for
certain applications or that reveals something special about the
operation or its interface. We do it now using an attribute 'style' with
a URI value pointing to the actual style.

In our discussions, we have come across the idea that maybe indicating
multiple styles on a single operation would be useful. On the other
hand, the possible solution making the attribute's value a list of URIs
was usually rejected fast, probably due to connotations with SOAP/1.1
attribute encodingStyle that could also contain more URIs but the rules
for combining the styles were prohibitively confusing.

I propose we get rid of the attribute 'style' on operations with an
interface and add the following attributes:

{http://www.w3.org/@@@@/@@/wsdl/style/rpc}rpcStyle='true'
(if the rpc:signature attribute is mandatory, the above is unnecessary)
{http://www.w3.org/@@@@/@@/wsdl/style/get-attribute}attributeStyle='true'
{http://www.w3.org/@@@@/@@/wsdl/style/set-attribute}attributeStyle='true'

These are extension attributes which, when used on an interface
operation, indicate that the operation follows the RPC (or get or set
attribute) style.

Pros:
      * indicating multiple styles is straightforward, the meaning of
        such a situation is clear
      * one less core-WSDL construct for those that don't care
      * the potential interface styles and message reference styles can
        be handled the same way

Cons:
      * a WSDL tool that doesn't know an extension cannot tell if it's a
        style or not
      * more global attribute declarations
      * with the value 'false', these attributes do nothing

Basically, this proposal makes the style hint just another extension
because that's what it is. 

I don't see much value in indicating that a given extension is an
operation style (that's the most substantial con AFAICS). It's only
useful in tools that display the WSDL to a user. If the tool doesn't
know a particular style, it can just display the URI and the user, after
clicking it, will see what the style is. But if it's just an extension
attribute and the tool doesn't know it (and expectedly displays it in
raw), the user will just click the namespace URI and see the same thing
as above. The semantic web technologies would allow us to say that a
particular extension is an operation style, but I don't see this
information as necessary in core WSDL.

Best regards,

                   Jacek Kopecky

                   Systinet Corporation
                   http://www.systinet.com/
Received on Monday, 19 January 2004 04:37:43 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Monday, 7 December 2009 10:58:28 GMT