This is Volume III of the long-awaited second edition of the 'bible' and expert guide to deploying, using, and managing IBM DataPower Gateway Appliances. It is updated through firmware version 7.2 and focuses on DataPower development. The authors present DataPower information and insights that are available nowhere else. Writing for working architects, administrators, developers, and security specialists, they draw extensively on their deep experience, helping IBM customers use DataPower technologies to solve challenging system integration problems. This volume focuses on all aspects of developing custom code for DataPower, including XSLT, JavaScript/GatewayScript and much more. The lead author is a DataPower original employee, responsible for creating and developing core sections of the WebGUI and other components of the products firmware and has the experience of performing scores of actual customer implementations. This volume walks through an introduction to DataPower development concepts and technologies, including XSLT, EXSLT, JSON, REST, XQuery, and JSONiq and then moves in-depth, providing a chapter on real world examples. The volume concludes by covering development tools and transforming secondary data formats. IBM DataPower appliances can simplify deployment, strengthen security, enhance performance, and dramatically improve return on investment for many use cases, such as mobile, Web, API, legacy, cloud, and SOA/Web Services. In this book, a team of leading experts show how to make the most of DataPower appliances in any IT environment.