FW: [plcs-dex] Referencing data within other exchange files

["John Dunford" <esukpc15@gotadsl.co.uk>]

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
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> >
> >
> >

Product-Data-Exchange_Annex_Reference-Mechanism.pdf