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Re: Rationale to close the operation overloading issue

From: <Jochen.Ruetschlin@DaimlerChrysler.com>
Date: Fri, 14 Jun 2002 15:43:15 +0200
To: <moreau@crf.canon.fr>
Cc: <joyce.yang@oracle.com>, <www-ws-desc@w3.org>
Message-ID: <0057440018428014000002L442*@MHS>

> I don't think the point is about the least common denominator, but about not 
tying
> a particular Web Service to a given implementation. Allow operation 
overloading
> would, IMO, just do that.

Seen from an implementational point of view, this is correct. But if you take 
operation overloading as a kind of structuring mechanism for adding more 
semantical information to the description, I think this is implementation 
independent. For example: I have one (logical) operation "getAddress" which 
returns the address of a certain person. With an overload mechanism I can 
express the fact, that the following operations are "instances" (not in an 
implementational way but in a logical) of an operation providing one certain 
functionality: returning an address of a person which is identified in 
different ways.

	getAddress(socialNo)
	getAddress(name, surname)
	getAddress(login)
	...

Having no overload mechanism results to a more or less unstructured and maybe 
missleading description (depending from the authors preferences), e.g.

<operation name="getAddressFromSocialNo" ....
<operation name="getAddressWithNameSurname" ...
<operation name="getAddressFromLoginInfo" ...

IMO it seems easier to map from WSDL to the PL then the other way round (for 
the last case see also the comment from Russel [1]).
Finally some mapping between the "ASCII-based" operation name and the real 
method name of the implenentation has to be done in any way. So, why it should 
not be possible to do so with additionally considering the message format (i.e. 
the input parameters)?

WSDL with overloaded ops	|	PL without overload ops.
======================================================================
getAddress(socialNo)		->	getAddressFromSocialNo(socialNo)
getAddress(name, surname)	->	getAddressWithNameSurname(socialNo)
getAddress(login)		->	getAddressFromLoginInfo(login)

Now it could be stated, that this again results to unstructured (and maybe 
missleading) method names as shown above in the oposite direction. But (1) 
there are no other possibilities in this PL (because we have no overload 
mechanism) and an implementation has to be done anyway in this way. And (2) I 
think we have to decide, if we want to have complicated identifiers in the 
description (i.e. the WSDL document), which is published, or in the 
implementation, which is usually private.

I'm not sure if additionally considering the input parameters for this mapping 
is such a big deal, apart from the fact that --- as far is I understand our 
activities --- we are focusing on the description of interfaces and not how to 
implement the mapping in a efficient way (which are implementation details).



So what I want to say is, that overloading of operations is not (only) an 
implementational aspect. It is a usefull feature and enhances the 
expressiveness of an interface description like WSDL . Yes, it's true that 
there are actually (not always trivial) implementation aspects which has to be 
considered when implementing the mapping, but IMO these seems solvable and are 
out of the focus of our activity. 

JM2p

jr. 

[1] http://lists.w3.org/Archives/Public/www-ws-desc/2002May/0172.html


Jochen Rütschlin
DaimlerChrysler · Research and Technology
Data and Process Management (RIC/ED)
P.O. Box 2360 · D-89013 Ulm (Donau) · Germany
Visitor's address: Wilhelm-Runge-Straße 11
Phone:   +49.731.505-2830
Telefax: +49.731.505-4401
Internet E-Mail: jochen.ruetschlin@DaimlerChrysler.com
Internet: 
http://www.informatik.uni-stuttgart.de/ipvr/as/personen/ruetschlin.html 



		
	moreau@crf.canon.fr
	14.06.2002 12:11
	Bitte antworten an moreau
	
	
		 
		 An: Jochen Ruetschlin/FT/DCAG/DCX@WK-EMEA2
		 Kopie: www-ws-desc@w3.org, joyce.yang@oracle.com
		 Thema: Re: Rationale to close the operation overloading issue

I don't think the point is about the least common denominator, but about not 
tying
a particular Web Service to a given implementation. Allow operation overloading
would, IMO, just do that.

Jean-Jacques.

Jochen.Ruetschlin@DaimlerChrysler.com wrote:

> As stated in 2.1 of our charter 
(http://www.w3.org/2002/01/ws-desc-charter#prog> ) the WSDL framework "is not 
geared towards any programming language". The
> other way round this could mean, that we should not exclude useful features
> only because some --- let me be more restrective and say: "exotic" in the 
sense
> of not used in a broad way --- programming languages does not allow function
> overloading.
Received on Friday, 14 June 2002 09:44:27 GMT

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