Why Web Services?

One of the primary advantages of the Web services architecture is that it allows programs written in different languages on different platforms to communicate with each other in a standards‑based way. SOAP is significantly less complex than earlier approaches, so the barrier to entry for a standards‑compliant SOAP implementation is significantly lower. The other significant advantage that Web services have over previous efforts is that they work with standard Internet protocols - XML, HTTP, and TCP/IP. A significant number of companies already have an Internet infrastructure, and people with knowledge and experience in maintaining it, so again, the cost of entry for Web services is significantly less than for previous technologies.

Exposing existing applications as Web services allows you to build new, more‑powerful applications that use Web services as building blocks. For example, you could develop a purchasing application to automatically obtain price information from a variety of vendors, allow the user to select a vendor, submit the order, and then track the shipment until it is received. The vendor application, in addition to exposing its services on the Web, could in turn use Web services to check the customer's credit, charge the customer's account, and set up the shipment with a shipping company.