Proposed changes to resource-metadata doc re WSDL

[Guy Rixon]

Hi,

at the WGL/exec meeting in Pune, we discussed briefly some clarification of
how WSDL and AccessURL work in service registrations.

Current situation is:

 1. RM document specifies Service.InterfaceURL as being the web resource
    describing the interface, i.e. WSDL or a web-form; by implication,
    the value is NOT the service endpoint, although the doc doesn't say this.

 2. XML schema doesn't cover InterfaceURL but does include AccessURL.

 3. AstroGrid people are unsure about what goes in AccessURL and have chosen
    to put the URL for the WSDL rather than the service endpoint.

Puting the WSDL location in AccessURL makes the registrations inconsistent
between SOAP and CGI services. For SOAP services, every client has to get and
parse the WSDL to find the service endpoint, which is wasteful. For CGI
services, there is nowhere to denote the WSDL if any were available (it IS
possible to write WSDL for CGIs and might be very useful).

I suggest that we make two additions to the the RM document:

1. Add Service.AccessURL. Specify that it MUST contain the URL for the service
endpoint and MUST not contain a URL for anything that pints indirectly to the
endpoint, such as WSDL. State that AccessURL is mandatory such that a client
of the registry can always find the service using that one metadatum.

2. Add Service.WsdlURL. Specify that it is optional but, if present, it MUST
contain the URL for the WSDL contract of the service. Furthermore, specify
that the contract MUST include a WSDL port element stating the service
endpoint. (I.e. if WSDL is present, the client may assume that it defines the
service location, not just the syntax of the interface.

We should retain Service.InterfaceURL but change the RM document to state that
this URL is not to be used for invoking the service but rather for getting a
human-readable description of the interface.

We need to add WsdlURL to the schema, too.

Cheers,
Guy

Guy Rixon 				        gtr at ast.cam.ac.uk
Institute of Astronomy   	                Tel: +44-1223-337542
Madingley Road, Cambridge, UK, CB3 0HA		Fax: +44-1223-337523