Although the benefits of Service-Oriented Architectures (SOA) are well-understood in the area of software engineering, e-learning platforms are commonly still implemented in the form of monolithic applications. The latter resemble one another to a large extend, but a reuse of functionalities between platforms in the form of services is uncommon or impossible. The reuse of e-learning content is addressed by many competing standards and specifications making the physical exchange of these learning objects difficult. The book of Peter Westerkamp transfers the concepts of SOAs to the field of e-learning. It starts with a short overview of the e-learning field and discusses different approaches to implement a SOA for e-learning. In addition, it defines reasonable e-learning services based on existing e-learning architecture standards. It turns out that the consequent design and implementation of e-learning functionalities in the form of Web services provides mechanisms to reuse e-learning functionalities and to create flexible platforms that can easily be adapted to the individual needs of learners. By using already existing standards from the field of Web services, functionalities can easily be integrated. Content, too, is delivered in the form of Web services, which makes a physical distribution of learning objects obsolete. This means that several e-learning standards and specifications are also obsolete because content is stored only once on the server of the content provider and accessed via Web services. The book covers models of the internal and external architecture of a Web-services-based e-learning environment. The service concept for e-learning is implemented in the Learn Serve environment and can be interpreted as a more general model for elearning Web services. The book also covers economical and organizational perspectives of e-learning Web services and discusses differences to monolithic platforms.