Re: [wsdm] some feedback on the interop scenarios doc

[David Melgar <dmelgar@us.ibm.com>]

"Springer, Ian P." <ian.springer@hp.com>
wrote on 03/21/2005 06:33:14 PM:

> It seems to me that in the MOWS Manageability References Act, the
> Manageability References capablity should be implemented by some sort
of
> singleton Web service (e.g. WeatherStationWebServiceRegistry), rather
> than by a particular Weather Station MOWS service. To me, it wouldn't
> make sense for a particular Weather Station MOWS service to expose
a
> GetManageabilityReferences operation that returns a list of Weather
> Station MOWS service EPRs. Is there something I'm misundertanding
here?

The GetManagebilityReferences operation is not a discovery
style operation to find weather service web services. The interop scenario
doesn't explain the usage well, but the relevant section in the MOWS spec
does.

GetManagebilityReferences is an operation added to
a functional web service, ie a web service who's primary purpose is some
business logic. In our example, it could be the weather station web service.
The response to this operation returns an EPR that is used to manage the
functional web service. It does not typically return weather station EPRs,
it returns an EPR to the management provider with associated reference
parameters if needed so that it can manage the weather station web service.
It may return multiple EPRs if multiple EPRs are used to manage the resource.

> It would be nice if the interop doc mandated
a more automated way of
> obtaining the EPRs for the three interop services, such as defining
a
> Web service with operations that return the EPRs (as the WSRF interop
> did for the printer EPR) or saying that the EPRs should be obtainable
> via HTTP GET requests. I think this would make it a bit easier for
> participants to point their clients at each other's services.

I'd second that. I'd prefer that the interop doc specify
that the EPRs are obtained by a HTTP GET request against a URL that maybe
given on a whiteboard, note, etc. The current interop doc says that an
EPR will be written on a whiteboard etc. This is complicated because an
EPR is represented as a blob of XML potentially with reference properties
etc. It maybe unnecessarily complex to copy down the XML from a whiteboard
to kick off the interop.

> Finally, section 4 specifies that the initial
EPRs should be WSA 2003/03
> EPRs, but I think it makes more sense for them to WSA 2004/08 EPRs,
> since this is the version that MUWS itself uses.

I'd prefer that we keep WSA 2003/03 as the initial
EPR version. Most of the interop scenarios involve sending requests to
implementations of 2004/06 versions of WSRF. This version of WSRF references
2003/03 WSA. Using 2003/03 WSA for initial EPRs reduces the potential versioning
issues with WSRF implementations.
Keeping the WSA versions straight during the interop
is complex. We're taking the approach of accepting either version and attempting
to send the specific version. 

David Melgar
Web Services Toolkit Development
Emerging Technologies
dmelgar@us.ibm.com