Oracle made a big decision a couple of years ago. The company decided to open certain aspects of its relational database management system (RDBMS) to manipulation by outside software. That architectural decision enabled a whole community of specialized software developers to thrive. In Oracle & Open Source, Andy Duncan and Sean Hull explore the universe of open source (that is, modifiable and largely free) software for Oracle applications. The authors approach the subject from two angles: that of database administrators who simply want to locate, download, and use tools that others have created, and that of the software developer who wants to learn about and take advantage of the hooks Oracle has built into its products. The downloaders will be pleased with documentation of Orac, Oddis, Karma, Oracletool, GNOME-DB, and other ready-to-run administration and design tools. The book explains what each tool does, where it comes from, how to install it, and how to use it (complete with hallmark O\'Reilly options lists in most cases). The programmer set, eager to contribute to the collection of open-source Oracle tools, will learn a lot from documentation of Oracle-specific libraries for various languages, including Oratcl for Tcl/Tk, several Perl modules, DCOracle for Python, and the Java Database Connectivity (JDBC) classes for Java. Some programmers may find the introductory sections too general in focus, but they\'ll be pleased by sections that explain the use of specific methods and functions.