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 prototypes, group communication stays confined to small niches and academic prototypes. In contrast, message-oriented middleware such as the Java Messaging Service (JMS) is widely used, and has become a de-facto standard. We believe that the lack of standard interfaces is the reason that hinders the deployment of group communication systems. Since JMS is well-established, an interesting solution is to map group communication primitives onto the JMS API. This requires to adapt the traditional specifications of group communication in order to take into account the features of JMS. The resulting group communication API, together with corresponding specifications, defines group communication primitives compatible with the JMS syntax and semantics.