Difference between a Message Broker and an ESB

Question

I have gone through different questions/articles on Message Brokers and ESBs(Even on stackoverflow). Still not a clue as what is the CLEAR demarcating difference between an Mess

Answer 1

Disclaimer: I am an IBM consultant and specialise in WebSphere ESB. This comment isn't left in any official capacity.

An ESB is more of an architectural pattern or concept than a product - broadly, a service-based way of engineering loose coupling. Its definition is fought over and not exactly set in stone. In general, an ESB is set of unrelated (in a technical sense) services - they expose interfaces, and they consume them from other services. Generally there isn't a hub and spoke architecture involved, although there can be.

IBM certainly markets both WebSphere Message Broker and WebSphere ESB as products that make it easy to build an ESB (along with the DataPower hardware appliance). They have different technological roots, but have some overlap in purpose. Also, that's not to say you can't build an ESB with lots of other things that aren't branded as an 'ESB product'.

That doesn't answer all your questions, but hopefully addresses the IBM part.