I am not sure that your definition clarifies anything. An answer to the following question would help: What is the concrete contribution of DS towards 'data virtualization'? Let us check this with an example for 'Grid focused' data virtualization. I would be good to know whether the following example is covered by your definition, and if yes, how is it supported by DS?
I assume that you are familiar with the ideas associated with ePC, RFID, PML, and ONS (see: http://www.epcglobalinc.org/) This is really a hot topic right now, especially through the mandates of Wal-Mart and DOD.
Let us assume that a manufacturer needs to recall a specific set of items of a product. Obviously, the current 'custodians.' of these items must be found. The query - using SQL as an example - would be:
SELECT * FROM 'Grid/Intenet' WHERE (ePC.identificaton BETWEEN ePC1 AND ePC2)
This query requires the retrieval of the history of all matching items from most likely many - potentially thousands - data sources (there is no single database containing all the information). It may take hours to gather all required data, failures are bound to occur, getting a complete result may even be impossible,. Some of the existing (Grid) infra-structure would most likely be stretched beyond its limit.
Again: I would be good to know whether this example is covered by your definition, and if yes, how is it supported by DS?
Dieter
Allen Luniewski wrote:
At the last face to face, Inderpal and I took away the action item to
define the term "data virtualization" from the OGSA Data Services document
more clearly. Below is the text we have come up with:Data virtualization is an informal, descriptive, term used in the OGSA
Data Services document to describe an abstract view of some data. The Data
Service (DS) provides a formal way to, define this abstract view of data
over data resource(s) and possibly other data services, and how to access
and modify data through this abstract view. The abstract view may be an
arbitrarily complex structure with no restrictions imposed by the DS
specification. The DS provides interfaces to, a) define, modify and
introspect the abstract view, b) access and modify the data via this
abstract view. This abstract view is provided by a Data Service with a
formally defined set of operations to access, and potentially modify, the
data as well as its structure. Within the Data Services document, the use
of the term "the data virtualization" is, in almost all cases, little more
than short hand for saying "the data accessible through the data service".Hopefully this helps to clarify the Data Services document.
Allen
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