Action item on optional extensions

In completion of my action item:
2004-12-02: DBooth to draft note clarifying that 
                (a) optional extension can change the 
                semantics; and (b) that if semantics are 
                going to change at runtime, it should be 
                indicated in the WSDL

Regarding part (a) of the above action item, we already have the
following text in section 6.3 Extensibility Semantics:
The presence of an optional extensibility element or attribute MAY
therefore augment the semantics of a WSDL document in ways that do not
invalidate the existing semantics. However, the presence of a mandatory
extensibility element MAY alter the semantics of a WSDL document in ways
that invalidate the existing semantics.

I suggest adding the following non-normative Note after the above
However, once the client and service both know that an optional feature
has been engaged (because the service has received a message explicitly
engaging that feature, for example), then the semantics of that feature
supercede what the WSDL document indicated.  For example, the WSDL
document may have specified an XML message schema to be used, but also
indicated an optional security feature that encrypts the messages.  If
the security feature is engaged, then the encrypted messages will no
longer conform to the specified message schema (until they are

Part (b) of the above action item is already covered by changes that I
proposed as a result of a related action item:


David Booth
W3C Fellow / Hewlett-Packard

Received on Wednesday, 2 February 2005 22:46:21 UTC