http://www.sajim.co.za/news.main.3nr4.asp?print=1


   
  Technical news Vol.3(3/4) December 2001

Web services - putting it all together 
Margaret van Steenderen 
Margaret.vansteenderen@commercequest.co.za 

Pierre van Dyk 
pvandyk@global.co.za 

The previous columns have discussed various innovative standards, which come together to 
produce Web services. According to Rhody (2001) the real value of Web services is the 
ability to 'unite companies in commerce transactions at the business process level'. The 
advantages of open standards, the ability to use current Internet infrastructure and platform 
and system independence aside, Web services very basically provide companies with the 
ability to communicate. 

What are Web services? 

Web services - these two words are receiving more and more press coverage, being touted 
as the next 'big thing' on the Internet. Supporters of Web services claim that it will change 
the face of electronic commerce forever. Detractors claim that it is nothing new, has been 
with us for years and once the hype is over will sink into obscurity. But what is a Web 
service, if one takes away all the hype? 

One definition for a Web service is 'a term used to describe technical services that are 
exposed via some public standard. Examples include purchasing services, catalogue 
services, search services, shipping or postal services exposed over transports like HTTP or 
electronic mail' (UDDI, 2000). 

The public standards used by a Web service have been defined - typically a Web service 
will be executed across HTTP (thus anybody with an Internet connection can use it). The 
message that will be sent - and the reply that may be received - will be in an XML 
format .The protocol used to format the messages is the Simple Object Access Protocol 
(SOAP). 

The above does not describe where the user will get information about a Web service, or 
how to access such a Web service, and this is where Universal Description, Discovery and 
Integration (UDDI) comes into the picture. UDDI describes a Web service, tells the user 
where it is and how to integrate it into another application. 

There are further XML-based standards that have appeared around Web services, namely 
WSDL that defines the endpoints of a Web service, WSFL that defines a flow language to 
model a business process flow between multiple Web services, and X-LANG, the Microsoft 
equivalent of WSFL. 

Why Web services? 

But what does all this mean? Why the interest in something that appears functionally 



equivalent to CORBA or DCOM, both distributed protocols that have been available for a 
much longer period than Web services?  

Everybody has heard of the client/server paradigm, where business logic is split off from the 
presentation view, thus allowing for loosely coupled systems that can easily grow over time. 
Web services introduce an even looser coupling due to the use of open standards like SOAP 
and HTTP. A Web service is designed from the outset to be platform, operating system and 
language independent; it does not enforce anything except the use of a transport mechanism 
- typically HTTP and the ability to produce and understand XML. One can thus view it as a 
type of client/service architecture, where services are exposed to a large number of clients. 

The loose coupling used by Web services allows pretty much any two computers linked to 
the Internet to be able to communicate with each other, irrespective of the operating system 
or programming language that is used on each of the computers. 

However, Web services do introduce some interesting questions that one needs to think 
about, such as issues around security. One can introduce certain security measures, such as 
using a secure transport protocol (HTTPS), but it still leaves one with the question of 
identifying users of a Web service. Another question is a more fundamental one - if 
software is going to be sold as a service, how does one charge for it? The user of a Web 
service will not be able to buy an off-the-shelf application or component, but will integrate 
to a service on an 'as required' basis. Different payment mechanisms (per use, per time 
period, etc.) can be envisaged, but again the issue of security comes to the fore. 

There is another fundamental difference between Web services and the other distributed 
protocols. Normally, a company that wished to integrate between a number of applications 
using CORBA or DCOM had to spend a fair amount of money as well as time to produce an 
application that was very specific to the problem at hand. Using Web services leads to an 
open application, one that is easily extendable. 

A last point in favour of the Web services route is the open standards around it - and support 
from all vendors on the various standards. Different vendors - even ones that in the past 
have been at loggerheads - agree on the different standards, thus ensuring that the tools used 
by different vendors all talk to each other in a seamless manner. 

Examples of Web services 

Not any application needs to be converted to a Web service, or to make use of it, but 
customer-targeted applications should consider it. Examples of applications well suited to 
be a Web service would be: 

The querying of parcel tracking within postal companies - instead of going to a Web 
site and getting the information one can query it using a Web service. One can also 
build such a query into a company-specific application, making it look part of the 
normal business flow and automating the check;  
doing a credit check on a person or company;  
trading shares across the Internet. The beauty of a Web service in such a situation is 
that it does not prescribe anything except the message format and where the service is 
located. Thus it does not enforce any other requirements.  

This does not mean that one is limited to only the above, hopefully it will give the reader an 
idea of the kind of Web services that may be published. 

Summary 



Web services is leading development of distributed applications using the Internet in a new 
direction - one that uses open standards and even open source (free) tools. It uses a 
ubiquitous transport protocol (HTTP) and XML standards to achieve its integration across 
different platforms, operating systems and languages. 

The Gartner Group estimates that 'Web Services will serve as an attractive means through 
which enterprises can gain access to software and business services. Through 2H02, 75 per 
cent of enterprises with greater than $100 million in revenue will interface periodically with 
Web services (0.8 probability). Through 1H03, 50 per cent of enterprises with less than 
$100 million in revenue will interface periodically with Web services (0.8 probability). This 
'next big thing' will fulfill on many of the broken promises of the past and present a 
compelling opportunity for enterprises of all sizes.' 

References 

Gartner Group (Andrews W, Plummer D, Smith D). 2001. How Web services mean 
business. Gartner Group Research Note. 

Rhody, S. 2001. The rise of Web services. Web Services Journal, Preview Issue, June 2001. 

UDDI.ORG. 2000. UDDI Programmer's API Specification. Available WWW:  

http://www.uddi.org (6 September, 2000). 

For additional information 

http://www-106.ibm.com/developerworks/Webservices/  - IBM's Web services zone, 
provides access to tutorials, discussion forums and overviews. 

http://www.w3.org/  - The W3C's site, do a search for Web Services, to find papers, 
'roadmaps' and workshops around Web services. 

http://www.sun.com/software/whitepapers.html#sunone  - Sun's software white papers, 
many relating to Web services. 

  

   

Disclaimer 

Articles published in SAJIM are the opinions of the authors and do not 
necessarily reflect the opinion of the Editor, Board, Publisher, Webmaster 
or the Rand Afrikaans University. The user hereby waives any claim 
he/she/they may have or acquire against the publisher, its suppliers, 
licensees and sub licensees and indemnifies all said persons from any 
claims, lawsuits, proceedings, costs, special, incidental, consequential or 
indirect damages, including damages for loss of profits, loss of business 
or downtime arising out of or relating to the user’s use of the Website. 

 

ISSN 1560-683X

Published by InterWord Communications for the Centre for Research in Web-based Applications,



Rand Afrikaans University