This extended abstract overviews some of the advantages and problems to overcome when implementing a publish/subscribe system over a wireless sensor network. Publish/subscribe usually relies on a set of intermediate nodes, brokers that gather and dispatch all the packets emissions. The presence of these brokers lightens the duty of most regular nodes, as they are the only ones who really need to know nodes identities and to maintain long-range routes. However, as computing power, memory, energy and channel bandwidth are scarce resources in WSN, defining an efficient brokering architecture is not trivial.

After presenting publish/subscribe in a wireless sensor network context, we examine various performance criteria and discuss on the brokering overlay. If a multi-brokers ar- chitecture seems necessary to distribute the load across the network, questions such as the correct number of brokers and their location are difficult when taking into account multiple criteria and that brokers need to remain synchronized. The dynamics of the system also requires attention, as brokers may appear or disappear according to the network traffic patterns or to battery levels.