In a world of pervasive computing where count-less computers and software component of different communicate permanently with each other a proper infrastructure to handle and monitor the traffic between the machines is required. They are referred to under the common name "Message oriented Middleware". There exist several architecture to fulfil this challenging task but the Enterprise Service Bus (ESB) architecture has proven to be superior to any other architecture in most common use cases. This seminar teaches what an ESB is, how it is implemented and used in practice and what commercial software exists to implement this principle.