[OGSA-D-WG] Stab at Glossary Terms

Wed May 2 03:54:46 CDT 2007

Allen,

I think your suggestion is a definite improvement.

Dave.

  _____  

	From: Allen Luniewski [mailto:luniew at us.ibm.com] 
	Sent: 01 May 2007 18:32
	To: Dave Berry
	Cc: ogsa-d-wg at ggf.org
	Subject: RE: [OGSA-D-WG] Stab at Glossary Terms

	Dave, 

	I like what is below but have a suggestion to make re "data
service".  How about changing it to read: 

	        Data service: A service that provides data access,
source or sink interfaces, as defined in this document, for one or more
data resources. 

	The intent of this suggestion is to make it clear that the data
service provides the SOA interfaces while still making it clear that the
data resource provides some other interface (typically not a service
interface) as a primitive on which the data service is built. 

	Allen Luniewski
	IBM Cross Brand Services
	IBM Silicon Valley Laboratory
	555 Bailey Ave.
	San Jose, CA 95141

	408-463-2255
	408-930-1844 (mobile)

"Dave Berry" <daveb at nesc.ac.uk> 

05/01/2007 08:56 AM 

To
Allen Luniewski/Almaden/IBM at IBMUS, <ogsa-d-wg at ggf.org> 
cc
Subject
RE: [OGSA-D-WG] Stab at Glossary Terms

	Here's an update based on today's call. 

	We finished the call by noting that in an SOA it is the service,
rather than the resource, that provides the access, source or sink
mechanisms.  We're not sure whether we need to revisit the definition of
resource (and its use in the other terms), although a data resource must
of course provide some access/source/sink mechanisms. 

	Dave. 

	Data Resource: An entity (and its associated framework) that can
provides a data access mechanism or act as a source or sink. 

	Source: A data resource that contains the data to be copied to a
sink via a data transfer mechanism. 

	Sink: A data resource that receives the data copied by a data
transfer mechanism from a source.   

	Data Access: Any mechanism that allows an entity to identify a
subset of the data held by a data resource and either return that data
to the requestor or to make it available for transfer elsewhere. 

	Data Transfer: A mechanism to physcially copy data from a source
to a sink. 

	Data Set:  An encoding of data in a defined syntax suitable for
externalisation outside of a data service, for example transfer to/from
a data service.  Examples include a WebRowSet encoding of an SQL query
result set, a JPEG encoded byte array, and a ZIP encoded byte array of a
set of files.  

	Data service: A service that provides data access, source or
sink mechanisms for one or more data resources. 

  _____  

	From: Allen Luniewski [mailto:luniew at us.ibm.com] 
	Sent: 18 April 2007 02:56
	To: Dave Berry; ogsa-d-wg at ggf.org
	Subject: RE: [OGSA-D-WG] Stab at Glossary Terms

	Dave, 

	Comments in-lien below. 

	Allen Luniewski
	IBM Cross Brand Services
	IBM Silicon Valley Laboratory
	555 Bailey Ave.
	San Jose, CA 95141

	408-463-2255
	408-930-1844 (mobile)

	"Dave Berry" <daveb at nesc.ac.uk> wrote on 04/15/2007 03:54:52 AM:

	> I think it's vital that we define these terms, because there
has 
	> been a lack of clarity for a while about the difference
between data
	> access and data transfer.  The existing definition of data
resource 
	> (originally from DAIS) doesn't distinguish between these two
modes 
	> in the way that we do, using source and sink to implicitly
refer to both. 
	>   
	> Comments inline => 
	> -----Original Message-----
	> From: ogsa-d-wg-bounces at ogf.org
[mailto:ogsa-d-wg-bounces at ogf.org] 
	> On Behalf Of Allen Luniewski
	> Sent: 13 April 2007 20:22
	> To: ogsa-d-wg at ggf.org
	> Subject: [OGSA-D-WG] Stab at Glossary Terms

	> 
	> At today's teleconference we agreed that we needed to firm up
the 
	> definitions in our glossary of the terms Data Resource, Data
Access,
	> Data Transfer, Source andonly Da Sink.  Currently ta Resource
has a 
	> definition taken from the OGSA Glossary) as: 
	>         An entity that can act as a source or sink of data
together 
	> with its associated framework. 
	> 
	> The confusion that was identified centered on the use of the
terms 
	> "source" and "sink".  The above definition is using them in a
fairly
	> generic way while the Data Architecture document uses them to
mean 
	> the source and sink of data transfers.  Here is stab at
defining all
	> 5 of these terms.  Once we have agreed on the definitions, we
may 
	> need to do some minor edits to the architecture document as a
result. 
	> 
	> Data Access: Data access is any mechanism that allows an
entity to 
	> identify data held by a data resource and receive that data
from the 
	> data resource.   
	> Can I suggest changing "identify data" to "identify a subset
of the data"? 

	Agreed.  Much better. 

	>   
	> I'm also not sure about saying "receive that data", as it may
not be
	> the requestor that receives the data (i.e. the data may be
sent to a
	> third party).  Would it work to say "and either return that
data to 
	> the requestor or to make it available for transfer elsewhere"?
I 
	> think Mario had a suggestion for some phrasing that might be
better 
	> than my attempt here. 

	I see your point and I agree that this needs to be fixed.  Your
suggestion works for me. 

	> Data Resource: An entity that can act as a source or sink of
data 
	> together with its associated framework.  By source we simply
mean an
	> entity that can originate data.  And by sink we simply mean an

	> entity that receives data.   
	> I'm not comfortable with using source and sink in a generic
fashion 
	> here and in a more restrictive fashion elsewhere in the
document (if
	> this is what you are suggesting).  I'd rather just refer
readers to 
	> the glossary definitions of these terms and make sure that all
the 
	> entries are consistent. 
	>   
	> An alternative definition that I suggested was, "An entity
(and its 
	> associated framework) that supports a data access interface,
or that
	> can act as a source or sink for data transfer", although I'm
not 
	> strongly wedded to that. 

	The problem is that in the context of data resource I don't want
to tie it into data transfer, at least not in the DMI sense of data.
The definition should include data that is stored/retrieved directly as
a result of a call on the data resource's API.  How about "An entity
that can receive data from a requestor or cause its data to be made
available to a requestor or a third party denoted by a requestor." 

	> Data Transfer: A mechanism to move data from a source of data
to a sink
	> of data.   
	> Should we say "copy" rather than "move"?   Should we also say 
	> "physically copy" or some such phrasing to distinguish this
from a 
	> mere renaming within a global namespace? 

	Yes, definitely "copy".  I missed changing this one when I
changed sink and source to "copy".  I am okay with physical copy
although personally I do not see it adding much value to the definition.

	> Source: A data resource that contains that data to be copied
to a sink via a 
	> data transfer mechanism. 
	> 
	> Sink: A data resource that receives the data copied by a data
transfer
	> mechanism from a source.   
	> Currently we use "source" and "sink" to mean interfaces on a
data 
	> resource.  I think we should make this clear.  We could use
the 
	> terms to mean both the resource and the interface, provided
that we 
	> are clear about what we are doing. 

	Should we add a phrase along the lines of "A sink is also the
interface provided by a data resource as part of its participation in a
data transfer."  And similarly for sink. 

	> 
	> Allen Luniewski
	> IBM Cross Brand Services
	> IBM Silicon Valley Laboratory
	> 555 Bailey Ave.
	> San Jose, CA 95141
	> 
	> 408-463-2255
	> 408-930-1844 (mobile) 

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