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 Referring to specific information inside an XML document is a little like finding a needle in a haystack: how do you differentiate the information you need from everything else? XPath and XPointer are two closely related languages that play a key role in XML processing by allowing developers to find these needles and manipulate embedded information. XPath describes a route for finding specific items by defining a path through the hierarchy of an XML document, abstracting only the information that's relevant for identifying the data. XPointer extends XPath to identify more complex parts of documents. The two technologies are critical for developers seeking needles in haystacks in various types of processing.

XPath and XPointer fills an essential need for XML developers by focusing directly on a critical topic that has been covered only briefly. Written by John Simpson, an author with considerable XML experience, the book offers practical knowledge of the two languages that underpin XML, XSLT and XLink. XPath and XPointer cuts through basic theory and provides real-world examples that you can use right away.

Written for XML and XSLT developers and anyone else who needs to address information in XML documents, the book assumes a working knowledge of XML and XSLT. It begins with an introduction to XPath basics. You'll learn about location steps and paths, XPath functions and numeric operators. Once you've covered XPath in depth, you'll move on to XPointer--its background, syntax, and forms of addressing. By the time you've finished the book, you'll know how to construct a full XPointer (one that uses an XPath location path to address document content) and completely understand both the XPath and XPointer features it uses.

Have you ever needed to share processing between two or more computers running programs written in different languages on different operating systems? Or have you ever wanted to publish information on the Web so that programs other than browsers could work with it? XML-RPC, a system for remote procedure calls built on XML and the ubiquitous HTTP protocol, is the solution you've been looking for. Programming Web Services with XML-RPC introduces the simple but powerful capabilities of XML-RPC, which lets you connect programs running on different computers with a minimum of fuss, by wrapping procedure calls in XML and establishing simple pathways for calling functions. With XML-RPC, Java programs can talk to Perl scripts, which can talk to Python programs, ASP applications, and so on. You can provide access to procedure calls without having to worry about the system on the other end, so it's easy to create services that are available on the Web. XML-RPC isn't the only solution for web services; the Simple Object Access Protocol (SOAP) is another much-hyped protocol for implementing web services. While XML-RPC provides fewer capabilities than SOAP, it also has far fewer interoperability problems and its capabilities and limitations are much better understood. XML-RPC is also stable, with over 30 implementations on a wide variety of platforms, so you can start doing real work with it immediately. Programming Web Services with XML-RPC covers the details of five XML-RPC implementations, so you can get started developing distributed applications in Java, Perl, Python, ASP, or PHP. The chapters on these implementations contain code examples that you can use as the basis for your own work. This book also provides in-depth coverage of the XML-RPC specification, which is helpful for low-level debugging of XML-RPC clients and servers. And if you want to build your own XML-RPC implementation for another environment, the detailed explanations in this book will serve as a foundation for that work.