WHAT YOU WILL LEARN IN THIS CHAPTER:
So far, you’ve learned what XML is, how to create well-formed and valid XML documents, and you’ve even seen ways of programatically interfacing with XML documents. You also learned that XML isn’t really a language on its own; it’s a meta language, to be used when creating other languages.
This chapter takes a slightly different turn. Rather than discuss XML itself, it covers an application of XML: web services, which enable objects on one computer to call and make use of objects on other computers. In other words, web services are a means of performing distributed computing.
It is often necessary to design distributed systems, whereby the code to run an application is spread across multiple computers. For example, to create a large transaction processing system, you might have a separate server for business logic objects, one for presentation logic objects, a database server, and so on, all of which need to talk to each other (see Figure 14-1).
For a model like this to ...