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Re: The Open Group SOA Ontology

From: Chris Harding <c.harding@opengroup.org>
Date: Mon, 21 Jul 2008 10:15:09 -0400
Message-Id: <200807210053.m6L0robe019703@postman.opengroup.org>
To: "Florian Lautenbacher" <lautenbacher_flo@gmx.net>, www-ws@w3.org, semantic-web@w3.org

Hello, Florian -

Thanks for your comments! Our ontology project 
team will consider them in developing the draft for formal review.

I would also like to post them publicly so that 
the debate on these and other comments can be 
conducted by everyone. Would you have a problem with this?

I'll give initial responses to your comments 
below. A general point is that the ontology 
touches on several different topics, but does not 
go into detail on any of them. It would clearly 
not be able to go into detail on all of them, and 
to address some in detail but not others would 
make the ontology rather unbalanced. What we 
would ideally like to do is to establish 
formally-defined relations with OWL ontologies in 
all of these areas. Unfortunately, they mostly 
don't yet have formal ontologies. Web services is 
an exception, and we do want to work on defining 
the formal relationship between this ontology and 
OWL-S. But for other areas, such as effects, 
rules, policies, QoS, costs, and contracts, 
well-developed and accepted OWL ontologies do not exist, so far as I know.

At 15:59 18/07/2008, Florian Lautenbacher wrote:
>Dear Chris,
>thanks for your email to the w3c-newsletter. I 
>read the first time about the SOA ontology and 
>think it's quite a good approach for describing 
>all the concepts in an SOA. However, I got a few 
>questions when I read through the specification 
>where I think you might help me with:
>-The SOA ontology says that it aims to be 
>(potentially) a basis for model-driven 
>implementation of an SOA. How shall this exactly 
>be done? Are there several levels of the 
>ontology defined in order to refine the ontology 
>in several models or are you thinking about some 
>automatical code generations (more general 
>ontology at top level and an additional 
>grounding to existing services lateron)?

The aim is that the ontology should potentially 
be a basis for model-driven implementation. We 
have not developed a formal process for using it 
for this purpose. I am aware of work that has 
been done to generate WSDL service definitions 
automatically from business domain ontologies. 
The SOA ontology could be used in conjunction 
with business-domain ontologies to do this 
consistently. Generatng full service 
implementations is much harder than generating 
the interface definitions and would need 
extensions to the ontology. We haven't explored 
this yet. Work in this area is much more advanced 
in the OMG. They do not use ontologies as such, 
but their approach does have some relation to 
ontologies. Exploring and developing this 
relation is probably the best way forward.

>-In other ontologies for web services there is 
>often the notion of input, output, preconditions 
>and effects (IOPE). There are effects in the SOA 
>ontology, but no preconditions defined on a service? Is this on purpose?

See the initial comment. We would prefer to link 
to other ontologies that have these concepts 
rather than incorporate them in ours.

>-The effect is simply an OWL-DL-class. Are any 
>languages envisioned for describing effects 
>(such as KIF, SWRL, RuleML or R2ML)? - KIF and SWRL are e.g. used in OWL-S.

Again, see the initial comment.

>-Rules and Policies: are there links or 
>recommendations to other languages that allow 
>the specification of Rules (SBVR, SWRL, URML, 
>etc.) or Policies (KAOS, Rei, Ponder2, etc.)?

And again.

>-Is there a way to specify non-functional 
>properties of a service (Quality of service, 
>costs, etc.)? Not only for software services, 
>but also for other services this would be quite 
>interesting (Joe's car wash does always cost $5, except on Sunday then it's $7)

And again. It could be that part of the TMF's 
NGOSS framework could be translated to a formal 
ontology with some of these concepts.

>-How is a contract detailed? Are there any 
>mandatory properties that need to be described? (e.g. costs)

Again, we don't have detail on this - and would 
look to link to outside sources for such detail.

>-Solutions: In the context of services one often 
>talks about goals that need to be achieved by 
>the composition of services. And this 
>composition is then normally a possible 
>solution. However, in your ontology I don't find 
>any correspondence between solution and 
>composition (or the notion of goal itself).

We don't have a notion of goal, but we do have a 
notion of requirement, and a solution is 
something that satisfies a requirement. We do, in 
section 4.8, define Orchestration and 
Choreography subclasses of the Composition class, 
to address two important kinds of service 
composition. The Solution and Composition classes 
are not disjoint, so a composition can be a solution.

>-Are there constructs that define how a 
>composition of services (in your terminology a 
>system) shall be achieved? (sequences, 
>alternative flows, etc.)? I didn't find any.

No, there are no such constructs. These are 
probably among the things that would need to be 
added if the ontology is to be used to drive full 
model-driven implementation. Again, though, we 
would prefer to link to another ontology (perhaps 
based on BPMN?) that has these constructs, if one exists.

>-The part about requirements, design and 
>implementation in my opinion is not that 
>specific for an SOA. Are there thoughts to 
>describe this in an own ontology (as e.g. the 
>Software Process Engineering Metamodel, SPEM, 
>simply focuses on these parts, too) and simply 
>integrate this other ontology into the SOA ontology?

We would have liked to import these from another 
ontology, but did not identify an appropriate 
one, and needed these concepts to explain others 
in the ontology. I understand that SPEM provides 
a means of describing activities, and there is in 
fact work elsewhere in The Open Group to use SPEM 
to model the phases of the Architecture 
Development Method of The Open Group Architecture 
Framework (TOGAF). From the point of view of our 
ontology, we don't analyse these phases in the 
way that the SPEM work does - we simply classify 
them as instances of the Architecture Development Activity class.

>-Concerning the messages and message types: how 
>is the relationship thought to WSDL or SAWSDL? 
>Are there already examples how WSDL (or better 
>annotated WSDL like SAWSDL) can be combined with the SOA ontology?

My understanding is that OWL-S incorporates WSDL 
concepts. I would see defining the relationship 
with OWL-S as the way of connecting our ontology 
with WSDL (but more work is needed on this).

>-How is the relationship to business process 
>modeling standards such as BPMN? You mentioned 
>that the SOA ontology related the Service to 
>other areas such as business process modeling but not exactly how.

I believe that our concept of Activity 
corresponds closely to the BPMN concept of 
activity, and see BPMN as providing a detailed 
analysis of concepts related to activity that we 
don't cover. Again, more work is needed to explore this properly.

>-Figure 25: Architecture Building Block is an 
>abstraction of Anything? How can the concept of 
>"Anything" be abstracted? Probably the arrow might go the other direction?

We use "Anything" as shorthand for "an instance 
of the OWL Thing class" - ie, anything in the 
universe of discourse. We are not saying that the 
concept of "anything" can be abstracted. We are 
saying that an abstraction of anything in the 
universe of discourse can be an ABB. So if 
"car-wash machine" is something in the universe 
of discourse, then "abstraction of car-wash machine" can be an ABB.

>-How is the Architecture Development Activity 
>linked to the Design? There is no connection in 
>your specification, but probably it might be 
>part of the design (as is the development of an 
>architecture often during the design phase in software engineering)

The relation between architecture and design is 
somewhat difficult to capture. As you point out, 
we haven't tried. But we don't preclude a 
relation. An architecture cannot be a design 
(because Architecture is disjoint with 
Abstraction, of which Design is a subclass). But 
I dont think there is any reason why a design 
shouldn't be an ABB, for example, or why a Design 
Activity shouldn't be a component of an 
Architecture Development Activity. If someone 
comes up with a specific need to establish this 
connection, we might explore this further, but we 
wouldn't want to do so otherwise.

>-A question not about the concepts in the SOA 
>ontology: Why didn't you use UML class diagrams 
>in your models? That would make it much easier 
>(at least for software engineers) to understand what they are about...

This is a good question. We haven't really 
considered using UML, but perhaps we should think about doing so.

>Thanks for clarification and best regards,

Thanks again for your very perceptive comments!

>  Dipl.-Inf. Florian Lautenbacher
>  Programming Distributed Systems Lab
>  Institute of Computer Science
>  University of Augsburg
>  Universitätsstr. 14
>  86135 Augsburg, Germany
>  phone:  +49 821 598-3102
>  fax:    +49 821 598-2175
>-------- Original-Nachricht --------
> > Datum: Tue, 15 Jul 2008 14:27:25 +0100
> > Von: Chris Harding <c.harding@opengroup.org>
> > An: semantic-web@w3.org, www-ws@w3.org
> > Betreff: The Open Group SOA Ontology
> >
> > Hi -
> >
> > For some time now, The Open Group has been developing a formal
> > ontology for SOA. We made an early version available for comment by
> > W3C members over a year ago. We have now reached the stage where we
> > believe that it is almost complete, and are exposing it to outside
> > bodies for review and comment prior to its final review within The Open
> > Group.
> >
> > The ontology is a formal OWL ontology, but the draft also includes
> > extensive heuristic explanations of its concepts. We believe that it
> > complements work on OWL-S and WSMO, in that it includes a compatible
> > concept of "Service" and relates this to concepts in other areas,
> > including Enterprise Architecture and Business Process Modeling.
> >
> > The draft is publicly available at
> > http://www.opengroup.org/projects/soa-ontology/doc.tpl?gdid=16940 We
> > would very much appreciate your input, not only on the relation of
> > this work to OWL-S and WSMO, but on all aspects that are of interest
> > to you. We will address comments received at this stage before
> > creating the draft for final Open Group review. I therefore invite
> > you to review the draft, and to send me comments on it.
> >
> > Regards,
> >
> > Chris
> > ++++
> >
> > ========================================================================
> > Dr. Christopher J. Harding
> > Forum Director for SOA and Semantic Interoperability
> > Thames Tower, 37-45 Station Road, Reading RG1 1LX, UK
> > Mailto:c.harding@opengroup.org Phone (mobile): +44 774 063 1520
> > http://www.opengroup.org
> > ========================================================================
> > The Open Group Conference & Member Meeting
> > Featuring the 19th Enterprise Architecture Practitioners Conference
> > InterContinental Hotel, Chicago, USA, July 21-25, 2008
> > http://www.opengroup.org/chicago2008/
> > ========================================================================
> > TOGAF is a trademark of The Open Group
> >
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Dr. Christopher J. Harding
Forum Director for SOA and Semantic Interoperability
Thames Tower, 37-45 Station Road, Reading RG1 1LX, UK
Mailto:c.harding@opengroup.org Phone (mobile): +44 774 063 1520
The Open Group Conference & Member Meeting
Featuring the 19th Enterprise Architecture Practitioners Conference
InterContinental Hotel, Chicago, USA, July 21-25, 2008
TOGAF is a trademark of The Open Group
Received on Monday, 21 July 2008 14:16:59 UTC

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