Bloom filter-based workflow management to enable QoS guarantee in wireless sensor networks

As a popular service composition technology, workflow has been successfully used in wireless sensor networks (WSNs) to compose a set of atomic services for service-oriented WSN applications. However, in a resource-constrained WSN, the sensed data is usually inaccurate or even missing, and this affects the normal execution of atomic services and may result in the non-guaranteed workflow QoS. Because the implementation of workflows in WSNs is usually hierarchical, effective workflow management in a WSN should consider both aspects of atomic services and sensor nodes, though this has largely been overlooked in existing research. Hence, a dynamic QoS-oriented, effective and efficient hierarchical workflow management mechanism is necessary. In this paper, we propose a Bloom filter-based hierarchical workflow management model, which coordinates both the atomic service level and the node level for guaranteed workflow QoS. Through constructing the service-level counting Bloom filter (CBF) to maintain the set of normal atomic services, and constructing the node-level Bloom filter (BF) to maintain the set of attribute strings of the current working nodes, an effective and efficient QoS degradation locating can be realized. Furthermore, the corresponding adaptation mechanism for guaranteed QoS is also developed. The case study and experimental evaluations demonstrate the capability of the proposed approach in WSNs.