The ESB architecture has a notion of a message context. In Web Services, the standard approach for this is OASIS WS-Context. Although our ESB is not tied to Web Services, it makes sense that we should support WS-Context. We already have an implementation that has been tested for interoperability with IONA and Oracle, so this is a good starting point. It will need some updating to bring it in line with the latest version of the specification.