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Semantics in Web Service: REST vs. WSDL -> which one is superior ?!

From: Shi, Xuan <xshi@GEO.WVU.edu>
Date: Fri, 18 Nov 2005 12:57:34 -0500
Message-ID: <D81F456794C18B4DA3E2ABC47DBBEEF2094E37@onyx.geo.wvu.edu>
To: "'Jim Hendler '" <hendler@cs.umd.edu>, "'public-sws-ig '" <public-sws-ig@w3.org>
Cc: "'zhexuan.song@us.fujitsu.com '" <zhexuan.song@us.fujitsu.com>, "'ryusuke.masuoka@us.fujitsu.com '" <ryusuke.masuoka@us.fujitsu.com>

>From its Web site: http://www.w3.org/TR/ws-arch/

W3C defines Web service as the follows:

For the purpose of this Working Group and this architecture, and without
prejudice toward other definitions, we will use the following definition:

[Definition: A Web service is a software system designed to support
interoperable machine-to-machine interaction over a network. It has an
interface described in a machine-processable format (specifically WSDL).
Other systems interact with the Web service in a manner prescribed by its
description using SOAP messages, typically conveyed using HTTP with an XML
serialization in conjunction with other Web-related standards.]

OK, there is no prejudice in its statement. But I just focus the first
sentence as: "A Web service is a software system designed to support
interoperable machine-to-machine interaction over a network." If this is
true, then I think W3C may limits its definition as "What is a WSDL Web
service?" since a real Web service designed to support interoperable
machine-to-machine interaction over a network can be deployed in other
approaches.

Below are examples for your kind attention:

WSDL Web services:

http://157.182.136.51/agswsprojs/geoWebService/Service1.asmx 
http://157.182.136.51/agswsprojs/geoWebService/Service2.asmx 
http://157.182.136.51/agswsprojs/geoWebService/Service3.asmx 

Purpose: to create a buffer feature of the input geospatial dataset at user
specified distance.

User interface: http://157.182.136.51/agswsprojs/geoWSviewer/WebForm1.aspx 

However, when I merge the two input variables into one description XML
document, then I can invoke the same function at a remote server by other
ways, such as HTTP/POST. This meets the definition of Web service - "A Web
service is a software system designed to support interoperable
machine-to-machine interaction over a network".

New WSDL Web service - one interface for all input specifications in one XML
document: 

http://157.182.136.51/agswsprojs/geoWebService/Service5.asmx

It performs exactly the same function as the one listed above:
http://157.182.136.51/agswsprojs/geoWebService/Service1.asmx 

For now, let's try HTTP/POST. Here is an HTTP server:
http://157.182.136.51/agswsprojs/HttpService/getService.aspx 

This HTTP server is waiting for a POSTed message sent as an XML document
with detailed service description and specifications. Once the server
receives the request, it will look for the function(s) specified in the
document, retrieve necessary input variables, invoke such function(s),
generate the response and send it back to requester.

To demonstrate the interoperable machine-to-machine interactions over the
Internet, the client interfaces are developed in .NET, Java Servlet/JSP, and
CGI/Python. The results are exactly the same if you want to try them at:

http://157.182.136.51/agswsprojs/HttpService/WebForm1.aspx (.NET)
http://157.182.136.51:8080/HttpApp/SimplePage.jsp (JavaServlet/JSP)
http://157.182.136.76/pyHttpClient/pyRequest.html (CGI/Python)

At last, let's consider the title of this message: Semantics in Web Service:
REST vs. WSDL -> which one is superior ?! Considering such 100 page WSDL
2.0? If we can describe service semantics in details, we can invoke it in
different ways, not just limited via WSDL, which may disappear once the
framework of semantic Web services are well defined and developed. 
 

-----Original Message-----
From: Jim Hendler
To: public-sws-ig
Cc: zhexuan.song@us.fujitsu.com; ryusuke.masuoka@us.fujitsu.com
Sent: 11/18/05 9:25 AM
Subject: re: Draft charters for work on Semantics for WS

I'm teaching a graduate seminar entitled "Advanced Semantic Web" here at
Maryland,  One of the people sitting in on the course is Zhexuan (Jeff)
Song, who works at Fujitsu Labs of America.  Jeff works on their Task
Computing project [1] which is focused on using semantics to compose Web
services, and he did a presentation last night comparing WSDL-S, OWL-S
grounding, data dictionary link and the WSDL to RDF mapping from the WSD
WG.    His slides [2] are the best discussion of this comparison I've
seen to date, and he has given me permission to post this note pointing
you to them --  for those trying to understand what is similar and
different about these approaches, and to understand some of the
vocabulary of this argument, these are a great starting place
 -Jim Hendler
p.s. if the WG is formed, I suggest Jeff's slides would be good to
include in the useful links section of their Web page.

[1] Task Computing: http://taskcomputing.org/
[2] Jeff's Slides: http://www.flacp.fujitsulabs.com/tce/WSDL-S.pdf
-- 
Professor James Hendler                   Director
Joint Institute for Knowledge Discovery                 301-405-2696
UMIACS, Univ of Maryland                    301-314-9734 (Fax)
College Park, MD 20742                       
http://www.cs.umd.edu/~hendler 
(New course: http://www.cs.umd.edu/~hendler/CMSC498w/)
Received on Friday, 18 November 2005 18:02:01 GMT

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