In one embodiment, a first one of a plurality of message processors receives a request with respect to a topic, and determines whether the first message processor itself is currently responsible for the topic. If so, then the first message processor services the request. If not, then the first message processor determines whether any of the other ones of the message processors is currently responsible for the topic. If so, then the request is redirected to another message processor to be serviced. If not, then the first message processor selects one of the message processors to be responsible for the topic and to service the request.