The stream system: a data collection and communication abstraction for sensor networks

Sensor network software is still in its youth. Due to sensor hardware limitations and the highly specific nature of application domains, existing software is generally poorly structured. It mixes data collection activities with data management, data storage/retrieval and intra/inter-sensor data communication with the actual data processing required by the application. We identify data collection, intra-sensor and inter-sensor communication as recurring activities in sensor network applications and propose a software module that abstracts these activities: the Stream System. Applications developed on top of if can be organized as a set of computational entities that are provided with a uniform view of such activities through the concept of streams. Streams represent a flow of data records that either (i) originate from a local transducer and can be read by a local entity, (ii) originate from a local entity and can be read by another local entity or (iii) originate from a local entity and can be read by a remote entity i.e., one running on a different sensor. Applications disregard the actual implementation details of collecting transducer readings and passing such data to other local or remote computational entities and rely on the Stream System to provide a record oriented data service in this respect.