Enterprise Service Bus (ESB) allows the integration of pervasive, distributed and networked systems more and more designed as a composition of atomic and heterogeneous services. Offered services have various types of Quality of Service (QoS) that can be unpredictable and may lead to undesirable situations such as service unavailability, high response time, decrease of reliability, etc. These kinds of situation may be unacceptable for service consumers or systems that require a more controllable reliability, efficiency, performance, etc. Being between the service providers and requesters, the goal of this paper is to show how efficient strategies can be associated to the ESB to give it the ability to guarantee or to take into account the satisfaction of non-functional requirements during the service mediation. Using a cloud-based deployment, we will show also how to guarantee the ESB scalability when a large number of concurrent services can be provided and consumed via the ESB.