Usually patterns provide indirections and abstractions, invoker and invokee are separated. This pattern acts opposite, exposes feature that is internal by its nature. Persistence Contexts are internal features of any EJB. The aim is to externalize it, to make it remote, a part of distributed environment.
This pattern was presented in Adam Bien’s Real World Java EE Patterns – Rethinking Best Practices and contributions belong to the author. The name Gateway comes from this publication.