Cloud computing markets face challenges, such as a large variety of different resource types in the market. A large variety of resource types results in a low number of matches of ask and bids. Consequently, the market has a low liquidity, which is economically inefficient and can lead to market failure. To counteract this problem, SLA templates (i.e., templates for electronic contracts) have been introduced. However, until now, SLA templates were static, not able to reflect changes in users ’ requirements. In this paper, we apply the adaptive SLA mapping approach for deriving public SLA templates from private SLA templates of users. To achieve the adaptation of SLA templates, we combine clustering algorithms with adaptation methods. The result is a set of new public SLA templates, which reflect the market situation more accurately. This way, we enable marketplaces to automatically adapt to observed changes of market conditions. For the simulationbased evaluation of our approach, we formalize a utility and cost model, calculate the overall net utility, and assess the scalability of the approach. Our results show that the use of clustering algorithms can significantly improve the performance of the adaptive SLA mapping approach. 1

Summary Cloud Computing represents a novel and promising approach for implementing scalable ICT systems for individual-, communities-, and business-use relying on the latest achievements of diverse research areas, such as Grid computing, Service oriented computing, business processes, and virtualization. From the technological point of view Grid computing is considered as the most related predecessor technology of Cloud computing. Although, Cloud and Grid computing differ in many aspects, as for example, in the general idea of the provision of computational resource, which is in Clouds commercial based and in Grids community based, there are many similarities. In this paper we investigate the similarities and differences between Clouds and Grids by evaluating two successful projects, namely for the provision of native hight performance copmputing applications as Grid workflows and for the self-management of Cloud infrastructures. ◮◮ ◮ Zusammenfassung Cloud Computing ist eine neuartige Methode für die Implementierung skalierbarer ICT Systeme, die von den Individuen, Gemeinschaften und Geschäftsprozessen benutzt wird. Cloud Computing basiert auf diversen Technologien wie z. B. Grid Computing, Serviceorientierte Architekturen, Geschäftsprozess-Management und