Software as a service (SaaS) providers exploit economies of scale by offering the same instance of an application to multiple customers typically in a single-instance multitenant architecture model. Therefore the applications must be scalable, multi-tenant aware and configurable. In this paper we show how the services in a service-oriented SaaS application can be deployed using different multi-tenancy patterns. We describe how the chosen patterns influence the customizability, multi-tenant awareness and scalability of the application. Using the patterns we describe how individual services in a multitenant aware application can be not multi-tenant aware while maintaining the overall multi-tenant awareness of the application. We show based on a real-world example how the patterns can be used in practice and show how existing applications already use these patterns.

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Adaptable pervasive flows are dynamic workflows situated in the real world that modify their execution in order to adapt to changes in the execution environment. This requires on the one hand that a flow must be context-aware and on the other hand that it must be flexible enough to allow an easy and continuous adaptation. In this paper we propose a set of constructs and principles for embedding the adaptation logic within the specification of a flow. Moreover, we show how a standard language for web process modeling (BPEL) can be extended to support the proposed built-in adaptation constructs. This work is partially funded by the FP7 EU FET project Allow IST-324449.

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