Book excerpt: In-depth examination of concepts and principles of Web application development Completely revised and updated, this popular book returns with coverage on a range of new technologies. Authored by a highly respected duo, this edition provides an in-depth examination of the core concepts and general principles of Web application development. Packed with examples featuring specific technologies, this book is divided into three sections: HTTP protocol as a foundation for Web applications, markup languages (HTML, XML, and CSS), and survey of emerging technologies. After a detailed introduction to the history of Web applications, coverage segues to core Internet protocols, Web browsers, Web application development, trends and directions, and more. Includes new coverage on technologies such as application primers, Ruby on Rails, SOAP, XPath, P3P, and more Explores the fundamentals of HTTP and its evolution Looks at HTML and its roots as well as XML languages and applications Reviews the basic operation of Web Servers, their functionality, configuration, and security Discusses how to process flow in Web browsers and looks at active browser pages Addresses the trends and various directions that the future of Web application frameworks may be headed This book is essential reading for anyone who needs to design or debug complex systems, and it makes it easier to learn the new application programming interfaces that arise in a rapidly changing Internet environment.