Group communication provides communication primitives with various semantics and their use greatly simplifies the development of highly available services. However, despite tremendous advances in research and numerous prototype, group communication stays confined to small niches and academic prototypes. In contrast, message-oriented middleware such as the Java Message Service (JMS) is widely used, and has become a de-facto standard. We believe that the lack of a well-defined and easily understandable standard is the reason that hinders the deployment of group communication systems. Since JMS is a well-established technology, an interesting solution is to extend JMS adding group communication primitives to it. Foremost, this requires to extend the traditional semantics of group communication in order to take into account various features of JMS, e.g., durable/non-durable subscriptions and persistent/non-persistent messages. The resulting new group communication specification, together with the corresponding API, defines group communication primitives compatible with JMS.