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Re: Feedback on Glossary (service type)

From: Stanislaw Ambroszkiewicz <sambrosz@ipipan.waw.pl>
Date: Fri, 2 May 2003 12:49:25 +0200 (CEST)
Message-Id: <200305021049.h42AnVh03901@ns.ipipan.waw.pl>
To: public-ws-chor@w3.org
Cc: arkin@intalio.com

>>>Jon Dart:
>>>So service type is just a more generic
>>>term and a WSDL interface is just part of the definition of that type.

Perhaps the following two examples may shed some light on the 
concept of service type.

A bit stupid example: 

Let's consider the arithmetic function called subtraction: 
minus(?x, ?y) 
The parameters are of type Integer; the values are also of the same type. 

The term "minus" is nothing but a name, that is supposed to denote 
the abstract function subtraction. 

Suppose that this abstract function was implemented as operation, 
however this implementation is partial, i.e., the operation performs 
the subtraction if and only if the parameters are non negative integer 
numbers, and ?y is less or equal than ?x. 
It means that the subtraction the operation performs is constrained 
to the domain of non negative integers. 

Suppose that this operation was exposed as a service. 
What is the type of this service? 
How this type should be expressed? 
---

A bit more realistic example: 

Suppose that there are two types of data: BookOrder, and BookInvoice. 
There is also an abstract function denoted by sellBooK( ?x ). 
The function takes an element of type BookOrder as its parameter and 
returns an element of type BookInvoice; this defines the interface of 
the function sellBook. 
However, the interface can not define the meaning of the function, 
i.e., what this function performs. 
Hence, there must be a specification of this abstract function in terms of 
attributes of the types BookOrder and BookInvoice. 
Suppose that there is also one attribute denoted by domain( ?x ) that specifies 
the domain of the book, i.e., IT, Medicine, belles-lettres, etc. 

Now, suppose that this abstract function was implemented as an operation 
and exposed as a service by a bookstore that sells books only 
from Information Technology domain. 
Note that the stock of the bookstore is dynamic, 
some books can not be available sometime. 

What is the type of this service? 
How this type should be expressed? 

Best regards, 
Stanislaw

-- Stanislaw Ambroszkiewicz

Institute of Computer Science,    mailto:sambrosz@ipipan.waw.pl
Polish Academy of Sciences       http://www.ipipan.waw.pl/mas/
Received on Friday, 2 May 2003 06:49:35 GMT

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