Understand the importance of Web services
Use the technologies underlying Web services
Write Web services using ASP.NET
Consume Web services
This chapter covers Web services from an ASP.NET perspective. Over the last few years “Web services” has emerged as a buzzword for enabling the next generation of computer connectivity. While networking a bunch of computers together isn't trivial, it's generally a solved problem these days. Most workplaces in the modern world depend upon an internal network of computers to allow the people staffing the enterprise to communicate and work effectively.
With the rise of the internal company network comes the desire to tie machines together programmatically as well. That is, a program on one machine should be able to call program methods on another machine without human intervention. Many enterprises spent nearly the entire final decade of the twentieth century trying to get their computers to talk to one another programmatically. On the Microsoft platform, this was usually done with Distributed COM (DCOM).
The next step in connecting computers is happening over the Internet. There's already a ubiquitous connection available (computers connected via HTTP) and a well-understood wire format (XML). Together, these two elements make up Web services.