Given these considerations, solving the routing problem can be seen as a choice among three alternatives. Common to the three alternatives is the need to broadcast some piece of information to all the servers in the network, where the broadcast is required by the lack of a priori knowledge of locality. The first alternative broadcasts notifications, which implies that notification matching is performed at each local server based on the subscriptions received at that server. This alternative suffers from the drawback that all notifications are delivered to all local servers, whether or not they are serving any parties inter- ested in the notifications. The second and third alternatives try.
