Revision with unchanged content. Context-awareness is a requirement of many modern applications. While several solutions exist to gather, represent and process context, very few provide management of context-aware data. In this book, a two-dimensional version model is presented, that allows managing context-dependent variants, while, at the same time, keeping track of the revision history. Queries are processed based on a matching algorithm that uses the current context of the system to select the best object. As an application of this extended database, a content management system has been designed and implemented. This Extensible Content Management System (XCM) provides a flexible platform for web engineering, built on the separation of content, structure, view and presentation. Metadata about these concepts is managed within the extended data­base and therefore all aspects of a web system become context-aware. Using XCM, a mobile tourist information system (EdFest) was developed. EdFest offers multi-channel interaction through standard web channels and a novel paper-based channel. This book is targeted at developers and researchers in mobile, ubiquitous and pervasive computing as well as in web engineering.