DO A GOOGLE SEARCH ON THE TERM “WEB Services” and you’ll come up with nearly three million hits—and literally thousands of individual references and resources—on the topic. Clearly, interest in Web Services is at an all-time high. Yet, despite this abundance of information, the concept of Web Services remains unclear to many business professionals. So, to help provide some clarity, consider the following “off line” analogy of a universal service known to all of us: the taxi. In any major city, step on to the curb, put your hand up in the air and everyone knows that you are trying to get a taxi. When a taxi stops to pick you up, you and the taxi driver will then engage in a simple, well-understood transaction.
The business rules and interactions involved in finding, using and paying for taxicab services are very well defined (in most places, at least). There is generally no need to explain the mechanics of the activity of moving people from the pickup point to the destination, nor the associated financial transaction. The world of taxi services is comparable to the world of Web Services in several important ways: discovery, protocols, entry points, authentication, payment and service availability.
Discovery
The existence of taxi services in any city is given. Taxis are usually labeled “TAXI” and marked in a distinctive yellow. They are typically listed in the local phone directory, similar to the Universal Description Discovery and Integration (UDDI) registry in the Web Services world so that interested outside parties can find a particular service.
UDDI enables a business to •describe its business and its services, •discover other businesses that offer desired services, and •integrate its services and products with the services of those other businesses.
Protocols