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

[Tim Turner <timturner11@bellsouth.net>]

Like I said,

I think it will be useful to review this after the session in Seattle.

The proposal was not to reference a P21 instance number. Please look at the
example again. (It's way down in the weeds of this email somewhere, along
with my rejection of Rob's assumption about instance numbers).

The requirement to have separate capabilities in order to reference the
contents of another increases both the number of capabilities (& their
maintenance) and confuses the scope of the Dexs. But that's just my own
opinion. Maybe others are happy with it.

Dave, I'd like to humbly suggest that the shipbuilding team did produce
something useful which may provide something to learn from - even though it
wasn't invented here (PLCS) and that some aspects may need to be brought up
to date / adapted for PLCS if considered. However, I freely admit that we
may be too far down the line for that. I have been trying to point out  an
alternative solution to the existing mechanism that has been tried & tested
& is now being implemented by several major vendors (e.g. Electric Boat,
Integraph ..). However, it may need some adaptation.

Rob, there is a correlation with what PLCS is doing & what was produced in
the shipbuilding arena. The protocols produced by T23 did not need to have a
set of separate schemas (ref.capabilities) to define objects that required
referencing (which are then pulled into the Dex).

For example, the protocol for ship structures (AP218) does not need to
define the entity moulded_form in order to reference the moulded_form
(defined in AP216) of a bulkhead (defined in AP218). In the PLCS method, I
would have to develop a ref.capability for referencing moulded forms and to
then pull that into the Dex (in this case AP218).

Will someone from ES planning to present this PLCS reference data mechanism
at Gerry's session in Seattle?

regards,
Tim



-----Original Message-----
From: David Price [mailto:david.price@eurostep.com]
Sent: 29 September 2004 10:17
To: plcs@lists.oasis-open.org
Subject: RE: [plcs] FW: [plcs-dex] Referencing data within other
exchange files


All,

Rob B's explanation of data consolidation is right on (or is that spot on
for Brits?). It's a fruitless exercise to build a capability into the
information model to refer between Part 21 files. People inside and outside
STEP have looked into this for years and produced nothing useful. I'd
encourage the PLCS/DEX team to learn from that wasted effort. Write a
guideline or place requirements on post-processors if you must, but don't
try and model Part 21 identifiers.

Cheers,
David

> -----Original Message-----
> From: Rob Bodington [mailto:rob.bodington@eurostep.com]
> Sent: 29 September 2004 15:02
> To: timturner11@bellsouth.net; john.dunford@eurostep.com;
> plcs@lists.oasis-open.org
> Subject: RE: [plcs] FW: [plcs-dex] Referencing data within
> other exchange files
>
>
> 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
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > >
> > >
> > >
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