Integration of heterogeneous information becomes again a requirement with the emergence of large-scale distributed applications such as Web-services based applications. Enterprise service buses (ESB) deals with distribution and communication, but they still do not fix all the mediation issues such as design, deployment and administration of mediators. It turns out however that current solutions are technology-oriented and beyond the scope of most programmers. In this paper, we present an approach that clearly separates the specification of the mediation operations basing on a service component model, and their execution on a distributed ESB. Model and ESB are independent of the targeted middleware used by applications. This work is made within the European-funded S4ALL project (services for all).