Cloud Computing: Read before Use -- Differential Erasure Codes for Efficient Archival of Versioned Data in Cloud Storage Systems -- Secure Integration of Third Party Components in a Model-Driven Approach -- Comprehending a Service by Informative Models -- Providing Ontology-Based Privacy-Aware Data Access through Web Services and Service Composition.

The LNCS journal Transactions on Large-Scale Data- and Knowledge-Centered Systems focuses on data management, knowledge discovery, and knowledge processing, which are core and hot topics in computer science. Since the 1990s, the Internet has become the main driving force behind application development in all domains. An increase in the demand for resource sharing across different sites connected through networks has led to an evolution of data- and knowledge-management systems from centralized systems to decentralized systems enabling large-scale distributed applications providing high scalability. Current decentralized systems still focus on data and knowledge as their main resource. Feasibility of these systems relies basically on P2P (peer-to-peer) techniques and the support of agent systems with scaling and decentralized control. Synergy between grids, P2P systems, and agent technologies is the key to data- and knowledge-centered systems in large-scale environments. This, the 30th issue of Transactions on Large-Scale Data- and Knowledge-Centered Systems, contains five in-depth papers focusing on the subject of cloud computing. Topics covered within this context include cloud storage, model-driven development, informative modeling, and security-critical systems.