RE: [PLCS] FW: Referencing data within other exchange files

[Nigel Newling <nfn@lsc.co.uk>]

Title: RE: [PLCS] FW: Referencing data within other exchange files

At risk of stepping into shark infested waters, may I add my three pennyworth?

At the launch of the DEX 3 team at IFS, Uxbridge (Where did they go ....?) we had a long debate about the role of DEXs in AP239. It was agreed that DEXs were specifically business orientated, with each DEX capable of standing alone as a data exchange to meet a specific business need. Where two or more DEXs overlap then their data sets could be added, using data objects common across the DEXs as integration keys. It was not, however, considered to be a specific role obligation on the design of a DEX to support data integration. This was considered to be a "free benefit" of DEXs, as implementations of AP239.

At a subsequent workshop at R-R, Filton, Bristol, it was agreed that there were, in essence, three types of Capability. Assigning capabilities allowed recurring packages of information, such as a date/time stamp, to be attached to almost any object in the DEX model. Representing capabilities would tell you everything you would ever reasonably want to know about the target. However, for many business processes, this package was considered to be an unnecessary exchange overhead when viewed in terms of the strict business needs of an individual DEX. It was, therefore, resolved to create "cut down" versions of most Representation capabilities. These versions would only supply the basic identity set of the target object. Although they were classified as Reference capabilities, they was not primarily intended to provide the link to the corresponding representation, although, using the DEX integration concept described above, the common ID component of the complementary pair does enable this to be done. So, for example, DEX 4, as a self contained data exchange to request that one or more maintenance tasks be undertaken, only needs to reference the parts that is to be repaired but allows the option of representing the tasks, if the service provider does not already hold a full task library from a DEX 3 exchange, or simply reference the task if it is known that he does.

Nigel

-----Original Message-----
From: John Dunford [mailto:esukpc15@gotadsl.co.uk]
Sent: 20 September 2004 09:47
To: plcs@lists.oasis-open.org
Subject: [plcs] FW: [plcs-dex] Referencing data within other exchange
files

A detailed explanation of one way of doing referencing is provided in
the attached ODETTE file, which those with long memories will recall was
a major source for the DEX concept.

John Dunford,
Eurostep Limited,
25, Chaucer Road, BATH BA2 4QX, UK
Tel: +44 1225 789347
Mobile: +44 0797 491 8202
www.eurostep.com
www.share-a-space.com
 

-----Original Message-----
From: Rob Bodington [mailto:rob.bodington@eurostep.com]
Sent: 17 September 2004 08:41
To: ''Plcs-Dex teams E-mail ' E-mail'
Subject: RE: [plcs-dex] Referencing data within other exchange files

I agree David, that is why we have written the referencing capabilities
to explain what information you need to exchange in order to be able to
uniquely identify something.

Regards
Rob

-------------------------------------------
Rob Bodington
Eurostep Limited
Web Page:   http://www.eurostep.com http://www.share-a-space.com
Email:  Rob.Bodington@eurostep.com
Phone:  +44 (0)1454 270030
Mobile: +44 (0)7796 176 401
Fax:    +44 (0)1454 270031 

> -----Original Message-----
> From: David Price [mailto:david.price@eurostep.com]
> Sent: 17 September 2004 08:03
> To: ''Plcs-Dex teams E-mail ' E-mail'
> Subject: RE: [plcs-dex] Referencing data within other exchange files
>
> A few opinions:-)
>
> If those are the requirements, I cannot imagine a worse solution than
> using any sort of OID like the Part 21 #number. Using an artificial
> identifier like that is not going to solve your problems. You need to
> use the "business
> identifier", for lack of a better term, and place requirements on
> post-processors to merge datasets whether than duplicate data. I don't
> think
> you can model yourself into solving this requirement. It's been
identified
> for years and has been built into a few technologies like URIs in OWL
but
> I've never seen a model of this that really works. You're back to the
> Globally Unique Identifier issue and something like a URI or "business
> identifier" are the closest thing we have.
>
> Cheers,
> David
>
> > -----Original Message-----
> > From: Rob Bodington [mailto:rob.bodington@eurostep.com]
> > Sent: 17 September 2004 07:47
> > To: ''Plcs-Dex teams E-mail ' E-mail'
> > Subject: RE: [plcs-dex] Referencing data within other exchange files
> >
> >
> > Hi David
> > The requirement is to be able to refer to something that has already
> > been exchanged.
> >
> > For example, on day one I send you the complete product structure of
> > an aircraft. A couple of days later I send you a Work request
> > relating to a particular version of a part in that product
> > structure. Clearly, I do not want to send you the complete aircraft
> > plus my work request. Instead I send you the work request plus
> > enough information to identify the subject (part
> > version) of the work request in your system. So I need to
> > send you part version, the part plus the identification
> > assignments that enable you to associate the work request
> > with the correct part version.
> >
> > So the "referencing" capabilities are intended to specify the
> > contextual information that is necessary to identify something that
> > has already been sent.
> >
> > Tim's proposal is to reference the OID in the Part 21 files. This
> > assumes that they are maintained. I had always assumed that a part
> > 21 file was transitory. In other words, you import it into you
> > system then discard it. Of course, some business processes require
> > you to retain the file for audit purposes.
> >
> > Regards
> > Rob
> >
> > -------------------------------------------
> > Rob Bodington
> > Eurostep Limited
> > Web Page:   http://www.eurostep.com http://www.share-a-space.com
> > Email:  Rob.Bodington@eurostep.com
> > Phone:  +44 (0)1454 270030
> > Mobile: +44 (0)7796 176 401
> > Fax:    +44 (0)1454 270031
> >
> >
> > > -----Original Message-----
> > > From: David Price [mailto:david.price@eurostep.com]
> > > Sent: 16 September 2004 23:28
> > > To: ''Plcs-Dex teams E-mail ' E-mail'
> > > Subject: RE: [plcs-dex] Referencing data within other exchange
> > > files
> > >
> > > As an alternative to creating a model supporting a reference to
> > > instances in other exchange files/databases, one could simply use
> > > implementation technology that natively supports it. For example,
> > > that's what Xlink was designed to do and that's one use of URIs in

> > > OWL. What *exactly* are the requirements?
> > >
> > > Cheers,
> > > David
> > >
> > > > -----Original Message-----
> > > > From: Tim Turner [mailto:timturner11@bellsouth.net]
> > > > Sent: 16 September 2004 01:45
> > > > To: 'Plcs-Dex teams E-mail ' E-mail
> > > > Subject: [plcs-dex] Referencing data within other exchange files
> > > >
> > > >
> > > > All,
> > > >
> > > > Following on from my previous email about referencing, if
> > we want to
> > > > truely reference something from another exchange then (if
> > there is
> > > > nothing that already lets us achieve the same) lets
> > create an entity
> > > > to handle it, e.g; something like...
> > > >
> > > > Entity external_instance_pattern
> > > >  instance_pattern : SET[1:?] external_instance_identification;
> > > >  name: string;
> > > >  description : OPTIONAL STRING;
> > > > End_entity;
> > > >
> > > > ENTITY external_instance_identification;
> > > >  source_id : STRING;
> > > >  source_type : STRING;
> > > >  instance_identifier : STRING;
> > > >  identifier_classification: external_class;
> > > >  description : OPTIONAL STRING;
> > > > END_ENTITY;
> > > >
> > > > This lets us create a reference to an instance within another
> > > > exchange file (it may since have been stored in a
> > database or other
> > > > system - but that is not our worry). It also lets us choose
> > > > which Dex or schema that the exchange was provided within (the
> > source_id),
> > > > the instance type (source_type), the identifier used, and the
> > > > classification that was used.
> > > >
> > > > Hence to reference a Part with the identifier "PSU-009"
> > classified
> > > > as a "part_type_code" that was exchanged using Dex001, we would
> > > > have;
> > > >
> > > > #1=external_instance_pattern((#2), 'simple design part
> > reference',
> > > > $); #2=external_source_identification('Dex001',
> > > > 'Part', 'PSU-009', #3, $); #3=external_class('Part_type_code',
> > > > $);
> > > >
> > > > More complex ones would be something like;
> > > > For a Version 1.1 of Part with the identifier "PSU-009"
> > classified
> > > > as a "part_type_code" we would have;
> > > >
> > > > #1=external_instance_pattern_identification((#2, #4),
> > 'simple design
> > > > part version reference', $);
> > > > #2=external_source_identification('Dex001', 'Part',
> > 'PSU-009', #3,
> > > > $); #3=external_class('Part_type_code', $);
> > > > #4=external_source_identification('Dex001',
> > 'Part_version', '1.1',
> > > > #5, $); #5=external_class('Version_code', $);
> > > >
> > > > For more complex patterns we just add another instance of
> > > > external_source_identification to the external_instance_pattern.
> > > >
> > > > If necessary (for unique & complete identification) we might
> > > > also need to add two other optional attributes to the
> > > > external_source_identification, such as; the organization and
> > > > date/time.
> > > >
> > > > This approach is compatible with re-using classification,
> > reference
> > > > data and is straight forward (to me at least!).
> > > >
> > > > To be used, external_instance_pattern would need to be a viable
> > > > option in the extensible select lists when doing an assignment -

> > > > e.g. when assigning a task, document, activity,
> > observation etc.. to
> > > > the item of interest being referenced.
> > > >
> > > > This may even help interoperability & even allow us to span data
> > > > over several files (if needed).
> > > >
> > > > Just something to think about- but comments welcome!
> > > >
> > > > regards,
> > > > Tim
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> >
> >
> >

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