Wireless Sensor Networks

7.5 Programming Beyond Individual Nodes: State-Centric Programming 277

Publish/Subscribe Group. A group may also be defined more dynam-

ically, by all entities that can provide certain data or services, or

that can satisfy certain predicates over their observations or internal

states. A publish/subscribe group (PSG) comprises consumers express-

ing interest in specific types of data or services and producers that

provide those data or services. Communication among members of

a PSG may be established via rendezvous points, directory servers, or

network protocols such as directed diffusion.

Acquaintance Group. An even more dynamic kind of group is the

acquaintance group (AG), where a member belongs to the group

because it was “invited” by another member ...