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Subject: Energy Market Information Exchange - XML message models, non-XML formats, DFDL

Hi Ed, Brian and Toby,

      I have been lurking on the smartgrid-interest list from OASIS, as I do not expect to become a formal member of any of these TCs (my IBM Research colleague Jane Snowdon has joined one; and my IBM Research colleague Ron Ambrosio has been involved in various angles of the NIST Roadmap).  But by way of self-introduction, I should say that I have long involvement in web scale evolvable data sharing technologies: I co-chaired the World Wide Web Consortium working group that product Resource Description Framework, I manage the central group at IBM Research working on core XML standards, processing libraries, and interpreters and compilers for XPath, XSLT, XQuery etc.  (We also do a lot of work with RDF query, Linked Data and OWL reasoners).  And I hope to help adapt our general purpose technologies to the needs of distributed operations of Smart Grids over the next 2+ years.  

     I want to comment on the idea that if we have a defintion of an XML message format for some information to be transmitted to another program or device, we still can have flexibility in both the transport, and in the format of the bits during the transmission.  

     There is a working group that defined a Data Format Description Language, which basically allows a correspondance to be expressed between a binary, columnar or compressed textual format, and the "logical" XML message structure that it corresponds to.  While some people might just use this as the formula for a physical rewriting by mapping -- concretely materializing the XML starting with the compressed format, one of my colleagues, Kristoffer Rose, demonstrated that certain kinds of XPath access code can use the "XML view" of the "compressed message" without necessarily doing the entire conversion -- something that is valuable if parts of the compressed messages are never accessed by some intermediatory logic -- for example, something which tests just a few fields and then routes the message one way or another.  

     If you are interested in more of Kris' thoughts, papers, examples..., see http://domino.research.ibm.com/comm/research_projects.nsf/pages/virtualxml.index.html .

     People pronounce the acronym for DFDL like the name of the flower "daffodil".

      If anyone on this list wants more info on DFDL, use your search engine to find the full specs, or look at a quick overview that Jim Myers of PNNL produced:


Senior Technical Staff Member and Manager
IBM Thomas J Watson Research Center
Hawthorne, New York, USA

Edward Koch <ed@akuacom.com>

08/12/2009 10:59 AM

Marty Burns <burnsmarty@aol.com>, "'Brian Frank'" <brian@skyfoundry.com>, "'Considine, Toby (Campus Services IT)'" <Toby.Considine@unc.edu>
"'William Cox'" <wtcox@coxsoftwarearchitects.com>, "smartgrid-interest@lists.oasis-open.org" <smartgrid-interest@lists.oasis-open.org>, "'Toby Considine'" <Toby.Considine@gmail.com>
RE: [smartgrid-interest] Energy Market Information Exchange Charter -         supporters wanted; ready for submission to create Technical Committee

The questions you raise concerning REST pertain to the description of the “service” that conveys the information and not necessarily to the information that is conveyed through that service.  For example in the current OpenADR spec there is am XML definition for the the so called EventState.  Furthermore there are specifications for how that EventState is conveyed using REST, SOAP, and BACnet web services.  Each of those differ in how the service for conveying the EventState is specified even though the information that is transported through each service is the same.
-ed koch

From: Marty Burns [mailto:burnsmarty@aol.com]
Wednesday, August 12, 2009 6:36 AM
'Brian Frank'; 'Considine, Toby (Campus Services IT)'
'William Cox'; smartgrid-interest@lists.oasis-open.org; 'Toby Considine'
RE: [smartgrid-interest] Energy Market Information Exchange Charter - supporters wanted; ready for submission to create Technical Committee

Pricing information will need to be conveyed by several protocols – from Web Services to compact binary SCADA. As such, we have to separate the information model from its conveyance. OASIS, I believe, will help to define the information model and at least one Web Services means. However, I think visibility of the need to convey the same semantics in other syntax’s should help guide the effort.
I am a fan of the “REST” ful type of modeling, as I understand it currently in a very limited way, in that it exposes rich information models with generic basic services to accomplish action.
Dr. Martin J. Burns
Hypertek, Inc.
14624 Country Creek Lane,
North Potomac, MD 20878
P - 1(301)315-9101
C - 1(301)257-9101

From: Brian Frank [mailto:brian@skyfoundry.com]
Wednesday, August 12, 2009 9:26 AM
Considine, Toby (Campus Services IT)
William Cox; smartgrid-interest@lists.oasis-open.org; Toby Considine
Re: [smartgrid-interest] Energy Market Information Exchange Charter - supporters wanted; ready for submission to create Technical Committee

My understanding as Bill said that this specification is about *modeling* - nothing to do with transactions or protocols.
If that is true, then the two most important aspects of modeling are:
  - type system
  - naming system
The type system is how we define data structures and contractual definitions.  I will assume that the "type system" will be XML Schema since it is the safe choice (despite being quite poor as a modeling type system).
The naming system is how we identify entities and reference them.  Any sophisticated model requires referencing things.  Independent of the protocols used, RESTful means that we leverage URIs for naming.
Both modeling and naming are areas which oBIX has really nailed.  But it doesn't sound like oBIX is being considered for the model - which is fine and to be expected.  But both the type system and naming system still matter a great deal, especially how they will interact with the overall system.
On Wed, Aug 12, 2009 at 8:59 AM, Considine, Toby (Campus Services IT) <Toby.Considine@unc.edu> wrote:

Restful interactions have their place. As APIs at a distance, they are clean and predictable. As part of transactional systems and open bidding markets, one needs the rest of the WS Transaction infrastructure. As part of a massively distributed delayed environment that may involve long running workflows, one may need a multi-document messaging based format.


Zooming in on REST is a little like zooming in on UDP, only a couple layers up. There are times when RESTful connections are exactly what one needs. There are times when they are not.



"A man should never be ashamed to own that he has been in the wrong, which is but saying ... that he is wiser today than yesterday." -- Jonathan Swift

Toby Considine

Facilities Technology Office
University of North Carolina
Chapel Hill, NC

  Email: Toby.Considine@ unc.edu
Phone: (919)962-9073


blog: www.NewDaedalus.com



From: Brian Frank [mailto:brian@skyfoundry.com]
Wednesday, August 12, 2009 8:42 AM
William Cox

smartgrid-interest@lists.oasis-open.org; Toby Considine
Re: [smartgrid-interest] Energy Market Information Exchange Charter - supporters wanted; ready for submission to create Technical Committee

Energy Market Information Exchange is an XML vocabulary to express price and characteristics, so the means of communicating is not part of the charter.


I can see how that is nice in theory, but I don't understand how that works in practice.  At the very least any sophisticated modeling requires naming things.  And naming things typically implies a way to reference those named things.


So I guess my question is - will the model be RESTful in that "things" are named and referenced with URIs?  


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