What Is Web Services?

Motorola’s vice president and Director of IT Toby Redshaw says of Web services, “If it is confusing, that means you are paying attention.” And it is. Web services is Internet or other IP-based network applications built with four emerging standards: XML, simple object access protocol (SOAP), Web services description language (WSDL), and universal description discovery and integration (UDDI). That allows the applications to talk to each other?no human intervention needed. What Web services is all about is interoperability of applications, be they written in Perl or Java or Windows or whatever.

This is how it might work: You start a website called HowLongCanILiveIn.com, which tells users how long their money would last them if they ran away to, say, Paris. And what the weather will be like. The thing is, you don’t want to write programs for currency conversions and weather forecasting. So you put up your website with a client application (a Web service) that will go to the “yellow pages”?UDDI?to find listed services that will meet your needs. There, your client application downloads the WSDL that gives it the information it needs to invoke the Web service for, say, currency conversion. Never mind that the one you find was written in Java and your program is written in C++; the data is described using XML tags that both applications can understand. Your message asking for the currency conversion application is embedded in a SOAP envelope and shipped out on HTTP, the standard Internet transport protocol. Meanwhile, another application is doing the same for weather information. Within the blink of an eye, your first user has determined that with her current life savings, she can live in Paris for one month, which will be under partly cloudy skies and in the 70s. How about Costa Rica?

Note the use of the word emerging above. The standards are still very much under development.