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

["Rob Bodington" <rob.bodington@eurostep.com>]

John
We took the Odette document as a starting point.
That is why we have implemented referencing capabilities.
I remain to be convinced that we need yet another means in a Part 21 file to
refer to some other entity in another part 21 file.

Data consolidation takes place in applications importing data.
When importing data, the data consolidation process needs enough contextual
information about an entity being imported to establish whether it already
exists in the database. It is the definition of that contextual information that
the Odette document and the referencing capabilities specify.

For example, if I send you a part, then send you a document assigned to that
part, the information that you need to establish that the two exchanges are
talking about the same part is the identification_assignment. Not the OID (#1
part etc) of the part in a Part21 file. The part 21 file may well be transitory.

Tim - I am not sure what this has to do with modules or ship building blocks?

Or have I missed the point completely.

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



-----Original Message-----
From: Tim Turner [mailto:timturner11@bellsouth.net] 
Sent: 29 September 2004 14:36
To: john.dunford@eurostep.com; plcs@lists.oasis-open.org
Subject: RE: [plcs] FW: [plcs-dex] Referencing data within other exchange files

John,

I think that it will be useful to review this in the light of Gerry's
session on Wed at Seattle.

I have offered to put something together on behalf of the shipbuilding
team - which used building blocks similar to modules (as a development
mechanism) and had a number of shorter schemas than the Ship Product Model
(read PLCS) that required - what I think - is a similar amount of
interoperability.

However, I will only have time to do that on the flight out there!

regards,
Tim


-----Original Message-----
From: John Dunford [mailto:esukpc15@gotadsl.co.uk]
Sent: 28 September 2004 13:34
To: plcs@lists.oasis-open.org
Subject: FW: [plcs] FW: [plcs-dex] Referencing data within other
exchange files


Dear All, do we now have an agreed way forward for the referencing
capabilities?  This is a key feature of the DEX concept as it provides
the means both to:

- handle net change
- grow an info set over time
- link data from one DEX to data from another.

At first sight it seems sensible, as Tim implies below, to have a single
referencing mechanism (if necessary with options within in) which could
be used by any DEX to point to ANY entity in PLCS to which reference was
needed.

I don't think this is an issue we should slide past without due thought
and attention!

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: Tim Turner [mailto:timturner11@bellsouth.net]
Sent: 23 September 2004 03:22
To: john.dunford@eurostep.com
Subject: RE: [plcs] FW: [plcs-dex] Referencing data within other
exchange files


Thanks John,

this does shed some light onto the history of where we are. However,
that doesn't solve the issue at hand (IMHO), about having to create a
capability for the sole purpose of representing entities to be
referenced from another.

What is does do, however, is to tell me that those entities used for
refernce purposes should be classified as such (in addition, I presume,
to the identification assignment). This is not mentioned in any of the
capabiltiies I've read so far.

I apprecaite all the hard work gone into the current solution but I see
a wealth of future confusion and issues around maintaining two
capabilities when one would do.

Someone once said that the capabilities are just building blocks for the
Dexs & that they were to be transparent to Dex implementors. If that is
the case, then we need to remove or re-package those listed within the
body of a Dex - but that's propbably another issue.

Best regards,
Tim

-----Original Message-----
From: John Dunford [mailto:esukpc15@gotadsl.co.uk]
Sent: 20 September 2004 04:47
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
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> >
> >
> >