About this Book

Jakarta Commons Online Bookshelf provides detailed technical information about 18 components from Jakarta Commons Proper and 1 component from the Commons Sandbox (Chain, module 13). Modules, which can be purchased individually from the Manning web site at www.manning.com/goyal, are organized roughly according to related concepts, as follows:

Web related?HttpClient (module 1); FileUpload (module 2); Net (module 3)
XML related?Digester (module 4); JXPath and Betwixt (module 5)
Packages?Validator (module 6); Collections (module 7); BeanUtils and Lang (module 8)
Utilities?Pool and DBCP (module 9); Codec (module 10); Modeler (module 11); CLI (module 12)
Frameworks?Chain (module 13); Logging and Discovery (module 14)

To cater to this book?s various audiences, each module is organized in a similar format; each module is divided into sections with their own area of relevance. You can skip sections, depending on whether you?re reading from a software developer?s point of view or that of a technical architect. However, the boundaries between the sections aren?t hard and fast, and there is nothing stopping you from reading a module from start to finish.

The structure of each module is as follows:

Introduce a component.
Develop the background for the component?s technology.
Explain the technology with examples, if necessary.
Explain the component?s structure.
Show beginning to intermediate (to advanced, in some cases) examples of using the component.

If you?re a software developer, and you aren?t interested in the background technology of a component, you can skip the beginning of each module and jump to later sections. On the other hand, if you want detailed information about the technology behind each component?for example, if you want to know about a component?s background protocols and rationale?you may want to read the first part.

To make the best use of this book, I suggest that you do read the information about the background technologies before you try the examples. This is especially important for components that involve varied and obscure technologies, such as Modeler (module 11). Knowing how Dynamic MBeans work makes the task of understanding the Modeler component much easier.

What?s covered?

As I said before, this book provides detailed examples and thorough background information about 18 Commons components. This section gives you a bird?s-eye view of what is covered in each module:

Module 1, HttpClient?A component that helps you deal with the client side of HTTP.
Module 2, FileUpload?The server end of the processing required for uploading files.
Module 3, Net?Provides implementations for a diverse range of Internet protocols like FTP, SMTP, NNTP, and so on.
Module 4, Digester?An XML-to-Java object mapping technology to help parse XML configuration files.
Module 5, JXPath and Betwixt?JXPath traverses complex objects using the XPath syntax, whereas Betwixt is a Java-XML mapping tool.
Module 6, Validator?Provides a guideline and API for validating user data from any source.
Module 7, Collections?Leverages the Java Collection API by providing several new collection classes and enhancements for existing ones.
Module 8, BeanUtils and Lang?BeanUtils works with the Java Reflection and Introspection API to provide access to JavaBeans properties, whereas Lang enhances the classes of the java.lang API.
Module 9, Pool and DBCP?Pool is an object pooling architecture, whereas DBCP is a precise implementation that uses it to manage database connections.
Module 10, Codec?Provides several common (and some not-so-common) encoding and decoding routines.
Module 11, Modeler?Provides an easy way to manage Model MBeans, which are used in Java Management Extensions.
Module 12, CLI?Provides an easy-to-use interface to deal with application startup options.
Module 13, Chain?An implementation of the Chain of Responsibility pattern.
Module 14, Logging and Discovery?Logging is used as a wrapper around existing logging implementations. Discovery is an attempt to provide common resource-finding services.

Each module is independent of the others, so you can jump straight to the component of your choice. There are no dependencies on prior learning; for example, knowing about Logging isn?t a prerequisite to learning about any other component. However, it?s expected that you know about Java, know how to download each component, know how to set Java CLASSPATH, and know how to code and compile. However, if you?re reading this book without doing any coding, you don?t need to know how to download or compile the components. The background reference material doesn?t assume any coding experience.

You can access each component?s web page by going to http://jakarta.apache.org/commons and following the individual links.