(Enterprise Service Bus) Universal integration backbone. An ESB acts as a shared messaging layer for connecting applications and other services throughout an enterprise computing infrastructure. It supplements its core asynchronous messaging backbone with intelligent transformation and routing to ensure messages are passed reliably. Services participate in the ESB using either web services messaging standards or the Java Message System (JMS). Originally defined by analysts at Gartner, ESB is increasingly seen as a core component in a service-oriented infrastructure.