Semantics of Zero to Many Resources

Many signals and communications that include resources may include more than one resource. There may be reasons to specify multiple resources in a single signal. This note discusses how this is communicated. While the information model describes this as a VEN element and 0 to many Resource IDs, for convenience and clarity here, I will annotate a call to the resources this as VENID( resourceID). Messages potentially direct to or describing resources include availability, opt, event signals, etc.

Let’s posit the VEN MyNode which has the resources identified by toaster, cooling, wellPump, blanket. A message sent to the smart toaster is written here as myNode( toaster). A message concerning the toaster and the blanket is myNode( toaster, blanket)

It may be desirable to communicate the same information about many resources. There may be a large number of resources exposed by some VENs. A setting the availability for all resources on a VEN is expressed using no resources, as in myNode(). This message is treated as if on receipt it were expanded to a list of all exposed Resources. Hereafter we refer to this pattern as the wildcard message.

If a single message contains both a wildcard and list of Resources, the wildcard is processed first, and treated as if it were expanded to a list of all resources. Those artifacts in the same message that express individual resources then act as if replacing the individual statements in that expanded information set.

Because the wildcard expression is treated as if expanded when received, it does not include additional resources which may be enrolled at a later time. If a Party wishes to include newly enrolled Resources, it should issue messages concerning those resources separately, or it should re-issue a new wildcard .

“The single biggest problem in communication is the illusion that it has taken place.”
– George Bernard Shaw.

Toby Considine
TC9, Inc

TC Chair: oBIX & WS-Calendar

TC Editor: EMIX, EnergyInterop

U.S. National Inst. of Standards and Tech. Smart Grid Architecture Committee

Email: Toby.Considine@gmail.com
Phone: (919)619-2104

http://www.tcnine.com/
blog: www.NewDaedalus.com

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