Summary

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This chapter discussed RPC, explaining how they could be used to implement distributed, network-based applications. It then went on to apply RPC theory to the web, examining how XML and HTTP could be combined to encode and transport procedure calls over the Internet and discussing two XML-based protocols, XML-RPC and SOAP, which are designed to do just that.

With the broad overview out of the way, this chapter then proceeded to a detailed examination of PHP's RPC extension, examining how it could be used to encode and decode RPC data, create and manage an RPC server, and examine itself to automatically deliver documentation on its available procedures. Finally, two real-world examples (and one not-so-real-world illustration) put the theory to the test, demonstrating how PHP and XML can be used to build distributed web applications such as a meteorological data retrieval utility and a POP3 mail notification service.

The next chapter will focus on connecting XML with other data sources, using a MySQL database to dynamically generate XML data, and apply XSLT stylesheets to it.

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