Re: Definitions and provenance and invariance

Graham, Stian, all,

I might be confused, but this seems a more complex model than the one
proposed by Jim and Luc.  Why do we need to both a Dynamic Resource
and a View Resource?  I can't see any meaningful difference between
them either in Graham's definition or Stian's (helpful) concrete
example.  What is the point of saying anything about a mutable
property, e.g. "content of DynamicResource i0", when any assertion of
a mutable property's value will not always hold anyway?

I think I must be missing something in your argument...

Thanks,
Simon

On 16 June 2011 15:39, Stian Soiland-Reyes
<soiland-reyes@cs.manchester.ac.uk> wrote:
> On Tue, Jun 14, 2011 at 12:09, Graham Klyne <GK@ninebynine.org> wrote:
>
>> Suppose that the "Dynamic resource has a number of different observable
>> properties, some of which do not change over time, and others which do.
>>  Then the View resource would be a resource for with a similar set of
>> properties such that do not change over time, but correspond to the dynamic
>> resource properties at a given time (including properties that do not change
>> over time).  If the Dynamic resource does not change over time, then it may
>> also serve as its own view resource:  the has view property can be
>> reflexive.
>>
>> The provenance resource is an assertion about the properties of the view
>> resource.  I believe the key requirement that we try to capture is that the
>> properties about which the provenance resource makes assertions are
>> invariant - there is no assertion in the provenance resource which is not
>> always true of the view resource.
>
>
> This is a very beautifully simple model which I think we should keep
> in mind before digging too much into the exciting discussions.
>
>
>
> "simplified" for the File example:
>
>
> :i0 a :DynamicResource ;
>  :name "/home/towns.txt" ;
>  :content [ :bytes "" ] ;
>  :creator :Alice .
>
>
> :i0View a :ViewResource ;
>   :viewOf :i0 ;
>   :name "/home/towns.txt" ;
>   :creator :Alice .
>
>
> # Metadata stored in filesystem
> :i0Provenance a :ProvenanceResource ;
>   :provenanceOf :i0View ;
>   :account :FileSystem ;
>   :processes (
>      [  :agent :Alice ;
>         :location :server1 ;
>         :process :fileCreation ;
>         :time "2011-06-15 18:00:01 UTC"  ]
>    ) .
>
> # however the log file claims the file was created on her workstation
> (not server), and 1 second later (clocks out of sync?)
>
> :i0Provenance2 a :ProvenanceResource ;
>   :provenanceOf :i0View ;
>   :account :ServerLogFile ;
>   :processes (
>      [  :agent :Alice ;
>         :location :AliceWorkstation;
>         :process :fileCreation ;
>         :time "2011-06-15 18:00:02 UTC"  ]
>    ) .
>
>
>
> ### New graph - Content changed
>
> :i0 a :DynamicResource ;
>  :content [ :bytes "New York\nLos Angeles\n"  ] ;
>  :name "/home/towns.txt" ;
>  :creator :Alice ;
>  :readBy (:Alice :Bob :Charles :David)
>
>
> :i2 a :ViewResource ;
>  :viewOf :i0 ;
>  :name "/home/towns.txt" ;
>  :creator :Alice ;
>  :content [ :bytes "New York\nLos Angeles\n"  ] .
>
> :i2Provenance a :ProvenanceResource ;
>  :provenanceOf :i2 ;
>   :account :FileSystem ;
>   :processes (
>      [  :agent :Alice ;
>         :location :server1 ;
>         :process :fileCreation ;
>         :time "2011-06-15 18:00:03 UTC"  ]
> # Lost as :FileSystem metadata only keeps last-modified
> #     [   :agent :Alice ;
> #         :location :server1 ;
> #         :process :fileWrite ;
> #         :time "2011-06-15 18:00:03 UTC"  ]
>     [
>         #  :agent :Bob;  - not recorded as only owner/creator is kept
>         :location :server1 ;
>         :process :fileWrite ;
>         :time "2011-06-15 18:14:12 UTC"  ]
>    ) .
>
>
> So say there are additional mutable properties such as :readBy above -
> would you consider those propagating into the view as mutable
> properties? There could be another view over :i2 for the file before
> it was read by Charles, where :readBy is an immutable property.
>
> The example graph above does not distinguish between mutable and
> immutable properties - perhaps we shouldn't as they could be difficult
> to find, identify and measure.
>
> Here :readBy is not kept by neither the log file or file system and is
> a kind of conceptual property - it could be discovered by simply
> asking everyone who could have read it, or inferred from traced file
> usage, like if its sent in an email.
>
> --
> Stian Soiland-Reyes, myGrid team
> School of Computer Science
> The University of Manchester
>
>
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-- 
Dr Simon Miles
Lecturer, Department of Informatics
Kings College London, WC2R 2LS, UK
+44 (0)20 7848 1166

Received on Thursday, 16 June 2011 14:51:16 UTC