W3C home > Mailing lists > Public > public-ws-semann@w3.org > June 2006

Re: why distinguish between simple and complex types? (issue 11)

From: Laurent Henocque <laurent.henocque@gmail.com>
Date: Tue, 06 Jun 2006 14:56:49 +0200
Message-ID: <44857B91.8080401@gmail.com>
To: Rama Akkiraju <akkiraju@us.ibm.com>
CC: SAWSDL public list <public-ws-semann@w3.org>

Hash: SHA1

I am also convinced that any complex data can be serialized in a string (names, dates, or more) and hence the
distinction between "simple" and "complex" has no semantical grounds but simply amounts to syntax.

I would also like to comment on your earlier suggestions (I am sorry a large number of issues seem to interact)

* references to "partial matches"

Going back to your several emails, I have the feeling that there may exist a confusion between references/mappings and
mediators. In my opinion, when annotating a WS, you should not have to list all possible mediations that exist from the
"main" designated reference to any other "related" type, even if as you said, this might be inserted automatically. To
support this, I would raise the dangerous issue that the introduction of a mediation from "Date" to "someType" would
suppose to update all the SAWSDLs that have Dates inside...

So I fully disagree with this:

> <element name="fullName" type=xsd:string
> sawsdl:modelReference="ontology#FullName"
> sawsdl:modelReference="ontology#FirstName"
> sawsdl:modelReference="ontology#LastName"/>

and would solely expect this:

> <element name="fullName" type=xsd:string
> sawsdl:modelReference="ontology#FullName"/>

But, this raises a very interesting issue (Jacek I sent a separate email for this):
When annotating an element: do we need to enforce the condition that there exists a one to one between the element type
space and the set of ontology instances?
If negative: what happens when a mapping raises an error? Do we have to provide hooks for error handlers in the

(the example above illustrates this: it is not possible to convert from a first fame to a full name)

* Lifting and lowering mappings

I think that we want semantics because we want to deal with discovery and mediation issues at an abstract, ontological
level. Henceforth, when attaching a modelReference to a WSDL element, my view would be that what is potentially needed
for invocation are both:
* lifting mappings : they take plain data and convert them to instances in the corresponding ontology. My understanding
is that at our level, we cannot make a single guess as to what this target ontology might look like. So a mapping can
solely ny a URI.
* lowering mappings : (again a URI) that take an ontology instance an convert it to data at the WSDL level.

('lifting', 'lowering' and 'mediation' belong to the DIP project's terminology)

Having this allows WS to interact via the logical system during invocation or composition by sequences: lifting /
mediation / lowering. Note that this intuition is the main argument for attaching mappings to the references they
"implement". However, the statement of mappings (to and from type/reference) could be made globally in the
specification, since this information is shared across all occurences of the "type".

* Discovery

Thinking about discovery: how a WS having a partially matching type can be discovered is beyond the scope of the SAWSDL
WG, since it amounts to reasoning. In fact, if one is looking for a "lastName", a query to her favorite reasoner should
come out with a ranking of matching ontologies sorted by relevance. Then a query to the WS repository would return  the
targets, accordingly sorted.


Rama Akkiraju wrote:
> Well, may be we don't need to distinguish simple and complex types after
> all. I sent that previous note too soon. :-). Here is a counter example
> where a simple type may also need a schema mapping (not necessarily for
> discovery but to support invocation)
> <element name="fullName" type=xsd:string />
> Say that in the ontology, there is a class called 'FullName' with two
> subparts 'FirstName' and 'LastName'. Then this simple type can be annotated
> in mulitple ways.
> <element name="fullName" type=xsd:string
> sawsdl:modelReference="ontology#FullName" />
> or
> <element name="fullName" type=xsd:string
> sawsdl:modelReference="ontology#FullName"
> sawsdl:modelReference="ontology#FirstName"
> sawsdl:modelReference="ontology#LastName"/>
> Both these above options are useful in discovery but may not be useful in
> invocation if the service interface to be matched with has elements
> 'firstName' and 'lastName')
> or
> <element name="fullName" type=xsd:string
> sawsdl:modelReference="ontology#FullName"
> sawsdl:modelReference="ontology#FirstName"
> sawsdl:modelReference="ontology#LastName"
> sawsdl:schemaMapping="URI#FullNameTokenizationLogicToMapToFirstNameAndLastName"/>
> This one has all the modelReferences that could aid in discovery and also
> has a string tokenization transformation function that provides explicit
> mappings to first name and last name.
> Regards
> Rama Akkiraju
> Rama Akkiraju/Watson/IBM wrote on 06/05/2006 05:59:03 PM:
>> Kunal,
>> Were you referring to precedence issues on these two examples?
>> because if so, these examples don't really present such issue. In
>> example 1, complex type annotaton doesn't really say anything about
>> what annotations apply to leaf node elements. So, there is no conflict.
>> I think when you mention conflicts you are talking about in the
>> context where a schema mapping is specified at a complex type in
>> addition to model references on the contained elements. If so, if I
>> understand you correctly you are making two independent points in
>> this e-mail. Is that correct?
>> So, here is a summary of  why we need to distinguish between simple
>> and complex types based on all the discussions.
>> a simple type can only have model references and no schema mappings
>> where as a complex type can have both model references and schema
>> mappings. These schema mappings specified at a complex type can have
>> an implication on the model references of simple types contained in
>> a complex type. That's why we need to differentiate simple and complex
> types.
>> Regards
>> Rama Akkiraju
>> kunal.verma1@gmail.com wrote on 06/05/2006 05:25:13 PM:
>>> Jacek,
>>> From our point of view, it would be nice to be able to annotate
>>> complexTypes, elements and simpleTypes. Jacek's example illustrates
>>> the first two (note, we changed the outer element to complexType).
>>> The second example illustrates the use of a simpleType.
>>> Example 1:
>>> <complexType name="Name" sawsdl:modelReference="ontology#name">
>>>    <sequence>
>>>       <element name="Title" sawsdl:modelReference="ontology#title"/>
>>>       <element name="First"
> sawsdl:modelReference="ontology#firstName"/>
>>>       <element name="Last"
> sawsdl:modelReference="ontology#familyName"/>
>>>    </sequence>
>>> </complexType>
>>> Example 2:
>>> <xs:simpleType name="fahrenheitWaterTemp"
>>>    sawsdl:modelReference="ontology#FahrenheitWaterTemperature">
>>>    <xs:restriction base="xs:number">
>>>       <xs:fractionDigits value="2"/>
>>>       <xs:minExclusive value="0.00"/>
>>>       <xs:maxExclusive value="100.00"/>
>>>    </xs:restriction>
>>> </xs:simpleType>
>>> Finally, allowing annotations for both elements and complexTypes
>>> begs the question of which takes precedence when used together. As
>>> pointed out by Laurent in http://lists.w3.org/Archives/P
>>> ublic/public-ws-semann/2006May/ 0043, the approach of giving the
>>> element annotation precedence over the type annotation seems like
>>> the way to go.
>>> "If some internal annotation exists for a complex type as well, any
>>> "where used" annotation takes precedence over the internal one."
>>> Thanks,
>>> John Miller and Kunal Verma
>>> On 6/5/06, Jacek Kopecky <jacek.kopecky@deri.org > wrote:
>>>> Hi all,
>>>> below is an excerpt from Rama's analysis of the relation of
>>>> modelReference and schemaMapping. The quoted part restricts
>>>> modelReferences to be allowed only on schema leaf elements.
>>>> On Sun, 2006-06-04 at 13:40 -0400, Rama Akkiraju wrote:
>>>>> Definition of Simple modelReference:
>>>>> ModelReferences that point to a single concept in the ontology via
>>>>> one-to-one association. Simple modelReferences are specified
>> at the level
>>>>> of individual (leaf) elements in an XSD.
>>>> Rama, I wonder why you have the restriction?
>>>> Using the common structured name example, one could have something
> like
>>>> this:
>>>> <element name="Name" sawsdl:modelReference="ontology#name">
>>>>   <sequence>
>>>>     <element name="Title" sawsdl:modelReference="ontology#title"/>
>>>>     <element name="First"
> sawsdl:modelReference="ontology#firstName"/>
>>>>     <element name="Last"
> sawsdl:modelReference="ontology#familyName"/>
>>>>   </sequence>
>>>> </element>
>>>> Basically, there is a trivial one-to-one correspondence between the
>>>> element Name and the ontology class "name". Do you think that
> expressing
>>>> this correspondence with modelReference may be harmful?
>>>> Best regards,
>>>> Jacek

- --
Laurent Henocque
Maître de Conférences Hdr
tel: +33 6 83 88 20 01
Enseignant à l'Ecole Supérieure d'Ingénieurs de Luminy - Marseille
Chercheur au Laboratoire des Sciences de l'Information et des Systèmes - Marseille

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Received on Tuesday, 6 June 2006 12:57:20 UTC

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