SOAP binding: empty SOAP Action

Our specification says, for specifying SOAP Action[2]:

  {soap action} OPTIONAL. A xs:anyURI, which is an absolute IRI as
  defined by [IETF RFC 3987], to the Binding Operation component. The
  value of this property identifies the value of the SOAP Action
  Feature for the initial message of the message exchange pattern of
  the Interface Operation bound, as specified in the binding rules of
  bindings to specific versions of SOAP (see 5.10.3 SOAP 1.2 Binding
  Rules for the SOAP 1.2 binding when the value of the {soap version}
  property of the Binding component is "1.2").

I.e., it doesn't allow an empty string as the value for {soap action}.

However, in SOAP 1.1, SOAPAction may be equal to ""[3], and the WS-I
BP 1.0 does allow it[1], which actually seems to be looser than what
WSDL 1.1 allows[4], but that's another story.

So I think that, in order to cover all the cases, we should allow the
empty string for {soap action} in addition to an absolute IRI.

SOAP 1.2 is not clear about whether an empty string is allowed or
not[5]. As it's not forbidden and "" is part of the value space of
xs:anyURI, I think it's fine.

So, for a concrete suggestion, I would like to proposed:

  {soap action} OPTIONAL. A xs:anyURI, which is an absolute IRI as
  defined by [IETF RFC 3987] *or an empty string*, to the Binding
  Operation component.

Cheers,

Hugo

  1. http://www.ws-i.org/Profiles/BasicProfile-1.1-2004-08-24.html#Describing_SOAPAction
  2. http://www.w3.org/TR/2006/CR-wsdl20-adjuncts-20060106/#soap-operation-decl-relate
  3. http://www.w3.org/TR/2000/NOTE-SOAP-20000508/#_Toc478383528
  4. http://www.w3.org/TR/2001/NOTE-wsdl-20010315#_soap:operation
  5. http://www.w3.org/TR/2003/REC-soap12-part2-20030624/#ActionFeature
-- 
Hugo Haas - W3C
mailto:hugo@w3.org - http://www.w3.org/People/Hugo/