OpenESB is a Java-based open-source enterprise service bus. It can be used as a platform for both enterprise application integration and service-oriented architecture. OpenESB allows developers to integrate legacy systems, external and internal partners and new development in business processes. It supports a multitude of integration technologies including standard JBI (Java Business Integration), XML with support for XML Schemas, WSDL, and BPEL with the aim of simplicity, efficiency, long-term durability, and low TCO (Total Cost of Ownership).
It used to be owned by Sun Microsystems, but after Oracle and Sun Microsystems merged (see: Sun acquisition by Oracle), the OpenESB Community was created to maintain, improve, promote and support OpenESB.