Brief Overview on Enterprise service Bus (ESB)

An enterprise service bus (ESB) provides provision for  a communication system between mutually communicating  software applications in a service-oriented architecture . ESB provides it services across various applications and across various message structures. If you imagine that your application recognizes one type of input, and it has to communicate with other application which recognizes entirely separate type of input. E.S.B operates as a moderator and makes communication possible between those two Applications which speak two diverse languages, in short ESB can be seen as  a translator. 

ESB implements a software architecture for spread computing, enterprise service bus implements a unique alternate for common client-server model. Whereas in broad any application using ESB can act as server or client in turns. ESB endorses dexterity and flexibility with regard to high protocol-level communication between applications. WebSphere Message Broker also provides similar service. It transforms routs & enhances the incoming message and broadcasts it to the output side.

As the below illustration exhibits the consumers are consuming services from the service providers via E.S.B.  Now Consumer-1 only understands ### and not anything else, that's the similar scenario with Consumer-2 who understands  *** only. Now they have to use services supplied by Provider-1 who can communicate only in $$$ followed by Provider %%% and HHH . imagine this scenario without E.S.B in the middle.

The E.S.B acts as a translator it transforms data coming from Consumer-1 into such format that it is well-matched with Service-1. this makes easier  the coupling between Service Consumer and Service Provider.