Enterprise Service Bus (ESB)
An Enterprise Service Bus (ESB) facilitates the transfer of data and intructions among services, processes, applications, existing internal systesm, data warehouses, analytical systems, and so on. The term bus is borrowed from computer architecture, since a computer bus similarly transfers data and instructions among components in a computer.
There are no standard features for an ESB. Nevertheless, all can serve as a router and all need to provide the functionality of adapters. This allows a designer to delegate routing, protocol conversion, and message transformation to the ESB.
An Enterprise Service Bus can also be offered in a Cloud.
More on the general topic: Messaging Components