Revision with unchanged content. Descriptions of data in the Semantic Web easily grow larger and more complex than the descriptions of traditional web pages and are thus more difficult to handle. The problem of how to structure complex systems has been addressed in traditional software engineering for decades and is commonly solved by splitting systems into components using different techniques. Recently, new techniques, like Aspect-Oriented Programming or the more generic Invasive Software Composition, were developed to fulfill newly emerging composition needs. These gray-box composition approaches access components through a well-defined interface, but modify internal parts of components during composition. This book investigates in trans­ferring composition techniques from the software engineering to the semantic web domain using the concepts of Invasive Software Composition. It shows how composition operators can be defined for software, query and ontology composition alike and how they can be tailored for specific needs of the Semantic Web domain. This book targets software engineers, researchers and students interested in modern software composition techniques and the emerging challenges of the Semantic Web.