[OGSA-D-WG] Fw: Definition of data consistency

[Mario Antonioletti]

Hi,
    Sorry I've been out of circulation. I am fine with the definition 
Dave though I think:

 	An instance of data in one resource....

reads a bit akwardly, would:

 	An instance of data in a resource....

not read the same way and slightly better?

Mario

On Wed, 10 Oct 2007, Allen Luniewski wrote:

>
>
>
>
> Dave,
>
> I like your enhancements.  I vote for moving forward with this new
> definition.
>
> 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
>             >                                                          To
>                                       Allen Luniewski/Almaden/IBM at IBMUS,
>             10/10/2007 01:47          <ogsa-d-wg at ggf.org>
>             AM                                                         cc
>                                       "Treadwell, Jem"
>                                       <jem.treadwell at hp.com>
>                                                                   Subject
>                                       RE: [OGSA-D-WG] Fw:  Definition of
>                                       data consistency
>
>
>
>
>
>
>
>
>
>
> I like this approach.
>
> Is it worth embellishing it as follows:
>
> Data consistency: An instance of data in one resource in a distributed
> system is said to be “consistent” with one or more other instances of that
> data elsewhere in the system if it is up-to-date with respect to those
> instances.
>
> In a given system a policy may define the rules for determining the extent
> to which data is up-to-date, and for maintaining that degree of
> consistency.
>
> The changes are:
>
> paragraph 1 - to talk about different resources in a distributed system
> (putting some context on "data instances", which is not a term we define).
>
> paragraph 2 - to introduce the notion of a degree of consistency rather
> than simply consistent/inconsistent.
>
> I don't feel strongly about either of these - what do others think?
>
> Dave.
>
>
>
> From: ogsa-d-wg-bounces at ogf.org [mailto:ogsa-d-wg-bounces at ogf.org] On
> Behalf Of Allen Luniewski
> Sent: 09 October 2007 17:50
> To: ogsa-d-wg at ggf.org
> Subject: [OGSA-D-WG] Fw: Definition of data consistency
>
>
>
> Please see Jem's note below - he can not post to this DL.
>
> I think that his suggestion is a good one.
>
> Allen Luniewski
> IBM Cross Brand Services
> IBM Silicon Valley Laboratory
> 555 Bailey Ave.
> San Jose, CA 95141
>
> 408-463-2255
> 408-930-1844 (mobile)
>
> ----- Forwarded by Allen Luniewski/Almaden/IBM on 10/09/2007 09:49 AM
> -----
>
>                         "Treadwell
>                         , Jem"
>                         <jem.tread
>                         well at hp.co
>                         m>                                             To
>
>                                               Dave Berry
>                         10/09/2007            <daveb at nesc.ac.uk>, Allen
>                         09:40 AM              Luniewski
>                                               <luniew at almaden.ibm.com>
>
>                                                                        cc
>
>
>                                                                   Subject
>
>                                               FW: [OGSA-D-WG] ***SPAM***
>                                               Definition of data
>                                               consistency
>
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>
>
> Allen/Dave, I can’t mail the data mailing list, so please feel free to
> pass this on if you think it’s worthwhile.
>
> I agree with Allen about sounding specific, and this is a hard thing to
> turn into a direct definition without using some term such as
> “indication.” You might think about using an indirect form:
>             Data consistency: An instance of data is said to be
>             “consistent” with one or more other instances of that data if
>             it is up-to-date with respect to those instances.
>
> That may be enough, but you could also add something like:
>             In a given system a policy may define the rules for
>             determining whether data is up-to-date, and for maintaining
>             consistency.
>
> - Jem
>
>
> Jem Treadwell
> Software Engineer
>
>
> HP ESS Software
> 856.638.6021 office | 856.638.6190 fax | jem.treadwell at hp.com
> 6000 Irwin Road | Mount Laurel | NJ 08054
> http://www.hp.com/go/vse
>
>
> hp
>
>
>
> From: Allen Luniewski [mailto:luniew at us.ibm.com]
> Sent: Monday, October 08, 2007 5:20 PM
> To: Dave Berry
> Cc: Treadwell, Jem; ogsa-d-wg at ogf.org
> Subject: Re: [OGSA-D-WG] ***SPAM*** Definition of data consistency
>
>
> Dave,
>
> I think that I am okay with that suggested change. I am a little bit
> worried about using the word "measure" as it can be taken to imply things
> that we really do not want to address (e.g., a means to measure and a
> quantifiable scale for measurement). I thought about suggesting changing
> "A measure" to "An indication" but that seems just a bit too vague to me.
> I don't have a better suggestion right now.
>
> Allen Luniewski
> IBM Cross Brand Services
> IBM Silicon Valley Laboratory
> 555 Bailey Ave.
> San Jose, CA 95141
>
> 408-463-2255
> 408-930-1844 (mobile)
>
> Inactive hide details for "Dave Berry" <daveb at nesc.ac.uk>"Dave Berry"
> <daveb at nesc.ac.uk>
>
>
>
>      "Dave Berry" <daveb at nesc.ac.uk>
>      Sent by: ogsa-d-wg-bounces at ogf.org
>
>
>      10/08/2007 02:11 PM                                               To
>
>                                                      <ogsa-d-wg at ogf.org>
>
>                                                                        cc
>
>                                                      "Treadwell, Jem"
>                                                      <jem.treadwell at hp.co
>                                                      m>
>
>                                                                   Subject
>
>                                                      [OGSA-D-WG]
>                                                      ***SPAM***
>                                                      Definition of data
>                                                      consistency
>
>
>
>
>
>
>
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>
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> Jem queried our definition of data consistency, which is currently:
>
>
> |--------------------------------------------------------------------------|
> | A policy that specifies or describes how up-to-date an instance of data  |
> | is in one service of a distributed system, with respect to one or more   |
> | instances of that data elsewhere in the system.                          |
> |--------------------------------------------------------------------------|
>
>
>
>
>
> Jem said (in e-mail):
>
>
> my thought was that data consistency would be a state of the data - it's
> consistent w.r.t. some other set of data or it isn't; the policy would be
> the rules that determine whether it is, and what the requirements are.
>
>
> I've had a look through our document and I agree. We refer to data
> consistency policies but also to data consistency requirements, mechanisms
> and strategies.
>
> So, how about this as a revised definntion:
>
> "A measure of how up-to-date an instance of data is in one service of a
> distributed system, with respect to one or more instances of that data
> elsewhere in the system."
>
>
> Best wishes,
>
> Dave Berry
> Deputy Director, Research & E-infrastructure Development
> National e-Science Centre
> 15 South College Street, Edinburgh, EH8 9AA
> +44 131 651 4039 www.nesc.ac.uk
> --
> ogsa-d-wg mailing list
> ogsa-d-wg at ogf.org
> http://www.ogf.org/mailman/listinfo/ogsa-d-wg
>
>

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|Mario Antonioletti:EPCC,JCMB,The King's Buildings,Edinburgh EH9 3JZ.   |
|Tel:0131 650 5141|mario at epcc.ed.ac.uk|http://www.epcc.ed.ac.uk/~mario/ |
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