[Fiware-data] FI-WARE-data / VisionDocument / Data-Context-Event definition - a proposed revision of the Event definition

[fano.ramparany at orange.com]

Hi,

I wish you the best for 2012 and in particular much success to our
FIWARE project and to the FI PPP program in general!

FT is involved in adding a semantic extension to the Publish/Subscribe
GE. One step required is to define a "semantic aware" data schema (*)
able to capture the Data-Context-Event model that has been defined in
the Vision Document.
While revisiting this chapter (the overview chapter:
https://forge.fi-ware.eu/plugins/mediawiki/wiki/fiware/index.php/Data/Co
ntext_Management#Overview), I felt uncomfortable with the definition of
an event, which according to the current version is "specific Data
Element" with a timestamp to represent its date/time occurence.

However, events are generally related to the creation of "element
attributes" or changes in the values of "element attributes" (for
example, if the temperature of the boiler has been measured 2 times and
its pressure 1 times. There will be 3 events, each of them will
correspond to a Context Element attribute. More precisely, 2 context
attributes for the two temperature measurements and 1 context attribute
for the pressure measurements. The timestamps of those 3 measurements
would probably be all different because the measurements would be done
at different times. The "element attribute" corresponding to the 2nd
temperature measurement will supercede the one corresponding to the 1rst
temperature measurement. (Note: with the approach proposed in the
working document I refer to below (**), the timestamp is a meta-data
associated to the "element attribute").

For this reason I'd like to propose a slight revision of the event
definition and state that "an event is a specific Data Element
attribute" (with a mandatory timestamp meta data to capture its
date/time occurrence). This definition would replace this one: "an event
is a specific Data Element".

Any comment/feedback on this and on the working document which proposes
a flexible ontology which aligns with our data model, is more than
welcome,

Best regards,

Fano

(* called an Ontology in the semantic web framework)

(** This document proposes an Ontology for Defining Ontologies for the
Pu ReleaseV0 <https://forge.fi-ware.eu/frs/shownotes.php?release_id=7> .
In case the link doesn't work, the document is in
FI-WARE->files->OntologyV0.pdf on the FI-WARE fusion forge web site)
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