Chapter 9. Python, Web Services, and SOAP

The Internet has opened many eyes to the possibilities of easily accessible digital information. With systems connected together, there is no reason why an airline ticket agent can't have an email sent to your hotel when you're boarding your flight 45 minutes late. Likewise, an Internet-enabled PDA and GPS should have no trouble automatically updating driving directions for you when notified that your hotel has changed due to overbooking. In other words, web services enable distributed systems to communicate with each other, sharing relevant pieces of user information to trigger the right kinds of events, alerts, and notices. However, web services hold a great deal of promise for those other than end-users or business travelers. For corporations, web services provide a greater degree of interoperability with trading partners, allowing the automation of business transactions and tighter integration between production and supply-chain systems. As previously mentioned, for humans, web services hold the promise of tying together distributed information in such a way that the Web can become a unified, seamless whole, regardless of a user's location or device. Understanding the impact of such innovation can shed light on the current interest in and excitement over web services. Understanding the technology behind them can give you the tools to create more powerful, integrated, and dynamic web applications.

Web services are distributed systems on the Web. When you visit a rich Internet portal, chances are much of the content that you see there was derived from sites talking to one another before the actual content is delivered to you; this is commonly referred to as content syndication. The technology behind this distributed model is just beginning to emerge and take hold. Typically, the components needed for servers to talk to one another include a common wire protocol and a common transactional protocol. If the wire protocol encapsulates external data formats, those formats must also be agreed on. When these elements are in place, it becomes possible for one service (such as a credit bureau) to talk to another (such as a financial web site).