[DAIS-WG] [dais-wg] Stepping Down as Co-Chair

[Norman Paton]

Hi,

It's interesting to hear that you are working on an implementation of 
the relational realisation. Would you be interested in participating in 
an interoperability testing activity for the specification? Such an 
activity is likely to follow the approach outlined for the XML 
Realisation in:

http://www.ggf.org/documents/GFD.77.pdf

There is another implementation being developed by the OGSA-DAI project 
at EPCC in Edinburgh, and there was an earlier implementation developed 
at IBM Hursley.

With respect to WSRF, the evolution of standards for representing state 
in web services is outlined in:

http://download.boulder.ibm.com/ibmdl/pub/software/dw/webservices/Harmonization_Roadmap.pdf#search=%22Microsoft%20IBM%20state%20web%20services%22

The basic lesson (from my perspective) is that this is a space in which 
agreement has been slow to emerge, and that as a result one has to 
conduct specification, software design and implementation activities on 
the assumption that current proposals will be superseded. 

The WS-DAI  specifications were designed to be conservative in their use 
of WSRF. The result of this conservative stance is that use of WSRF is 
optional in the specifications, and where WSRF is used, this makes 
little difference to the functionality of the service provided.

I don't think it's easy to provide advice for ongoing development 
projects that are currently using WSRF as to how to proceed, but all 
should proceed on the basis that WSRF will not be around for ever. As 
Malcolm describes, the OGSA-DAI team has architected their software in 
such a way as to allow multiple web service interfaces to be developed 
relatively easily in a thin layer. If you do use WSRF, you should 
certainly consider a similar approach. However, this approach helps the 
providers of a service and not the users of a service to cope with 
change. In the WS-DAI specifications, abstract names are mandatory in 
message bodies; this means that message bodies are the same whether or 
not you use WSRF. This looks like quite a good design decision with 
hindsight!

By contrast, I think it is easy to provide advice to standards 
activities as to what use they should make of WSRF or its emerging 
descendents!  ;-)

Regards, Norman