Endong Tong

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.

Context-Aware Service Ranking in Wireless Sensor Networks

Wireless sensor networks (WSNs) are widely used in practice for comprehensively monitoring and gathering physical information via a multitude of sensors. As the development of WSNs, the integration of them with the external Internet is a urgent need. By wrapping the sensor functionality as a WSN service, the Web service is considered as the most promising technology to incorporate WSNs into the Internet. The quest for selecting the service with the best performance promotes service ranking technology. However, due to the dynamic WSN environment, traditional quality of service (QoS) based ranking approaches for general Web services are no longer suitable for the WSN service. In this article, in order to fit the characteristics of the WSN environment, we propose a context-aware WSN service ranking approach by aggregating the user rating and WSN service context. First, the User QoS Assessment(UQA) and Context QoS Assessment(CQA) are proposed, respectively. Then, through the performance influence on the WSN service by the variations in their context, a Fuzzy mechanism is further developed to aggregate the UQA and the CQA. Finally, the experiments are presented to confirm the validity of the proposed approach.

Hierarchical workflow management in wireless sensor network

To build the service-oriented applications in a wireless sensor network (WSN), the workflow can be utilized to compose a set of atomic services and execute the corresponding pre-designed processes. In general, WSN applications rely closely on the sensor data which are usually inaccurate or even incomplete in the resource-constrained WSN. Then, the erroneous sensor data will affect the execution of atomic services and furthermore the workflows, which form an important part in the bottom-to-up dynamics of WSN applications. In order to alleviate this issue, it is necessary to manage the workflow hierarchically. However, the hierarchical workflow management remains an open and challenging problem. In this paper, by adopting the Bloom filter as an effective connection between the sensor node layer and the upper application layer, a hierarchical workflow management approach is proposed to ensure the QoS of workflow-based WSN application. The case study and experimental evaluations demonstrate the capability of the proposed approach.

Reasoning-Based context-aware workflow management in wireless sensor network

Workflow technology is regarded as the automation of an execution process in which the information or tasks are passed from one service to another, according to the predefined execution sequence. Recently, workflow technology has been successfully used in wireless sensor networks (WSNs) for service composition. Although workflows can dynamically change according to current context, there is still limited work to facilitate the atomic services reuse. In this paper, we propose a reasoning-based context-aware workflow management(Recow) approach, in which a rule-based reasoning module is responsible for extract semantic information so that the lower sensor data will have a loose couple connection with the upper logic process. By using the semantic information as service I/O, we reconstruct atomic services, then they can be reused in workflow construction. Usually more than one rule will be matched and they can not be executed simultaneously in the rule matching process, so a conflict resolution algorithm is further proposed based on context-aware priority. Finally, two case studies demonstrate that our approach can effectively facilitate resource reuse and also indicate the performance of the Recow approach as well as the precision of the conflict resolution algorithm.

Energy Efficient Sleep Schedule with Service Coverage Guarantee in Wireless Sensor Networks

Service oriented architecture has been proposed to support collaborations among distributed wireless sensor network (WSN) applications in an open dynamic environment. However, WSNs are resource constraint, and have limited computation abilities, limited communication bandwidth and especially limited energy. Fortunately, sensor nodes in WSNs are usually deployed redundantly, which brings the opportunity to adopt a sleep schedule for balanced energy consumption to extend the network lifetime. Due to miniaturization and energy efficiency, one sensor node can integrate several sense units and support a variety of services. Traditional sleep schedule considers only the constraints from the sensor nodes, can be categorized to a one-layer (i.e., node layer) issue. The service oriented WSNs should resolve the energy optimization issue considering the two-layer constraints, i.e., the sensor nodes layer and service layer. Then, the one-layer energy optimization scheme in previous work is not applicable for service oriented WSNs. Hence, in this paper we propose a sleep schedule with a service coverage guarantee in WSNs. Firstly, by considering the redundancy degree on both the service level and the node level, we can get an accurate redundancy degree of one sensor node. Then, we can adopt fuzzy logic to integrate the redundancy degree, reliability and energy to get a sleep factor. Based on the sleep factor, we furthermore propose the sleep mechanism. The case study and simulation evaluations illustrate the capability of our proposed approach.

Recover Fault Services via Complex Service-to-Node Mappings in Wireless Sensor Networks

With the motivation of seamlessly extending wireless sensor networks to the external environment, service-oriented architecture comes up as a promising solution. However, as sensor nodes are failure prone, this consequently renders the whole wireless sensor network to seriously faulty. When a particular node is faulty, the service on it should be migrated into those substitute sensor nodes that are in a normal status. Currently, two kinds of approaches exist to identify the substitute sensor nodes: the most common approach is to prepare redundancy nodes, though the involved tasks such as maintaining redundancy nodes, i.e., relocating the new node, lead to an extra burden on the wireless sensor networks. More recently, other approaches without using redundancy nodes are emerging, and they merely select the substitute nodes in a sensor node’s perspective i.e., migrating the service of faulty node to it’s nearest sensor node, though usually neglecting the requirements of the application level. Even a few work consider the need of the application level, they perform at packets granularity and don’t fit well at service granularity. In this paper, we aim to remove these limitations in the wireless sensor network with the service-oriented architecture. Instead of deploying redundancy nodes, the proposed mechanism replaces the faulty sensor node with consideration of the similarity on the application level, as well as on the sensor level. On the application level, we apply the Bloom Filter for its high efficiency and low space costs. While on the sensor level, we design an objective solution via the coefficient of a variation as an evaluation for choosing the substitute on the sensor level.

Exploring probabilistic follow relationship to prevent collusive peer-to-peer piracy

P2P collusive piracy, where paid P2P clients share the content with unpaid clients, has drawn significant concerns in recent years. Study on the follow relationship provides an emerging track of research in capturing the followee (e.g., paid client) for the blocking of piracy spread from all his followers (e.g., unpaid clients). Unfortunately, existing research efforts on the follow relationship in online social network have largely overlooked the time constraint and the content feedback in sequential behavior analysis. Hence, how to consider these two characteristics for effective P2P collusive piracy prevention remains an open problem. In this paper, we proposed a multi-bloom filter circle to facilitate the time-constraint storage and query of P2P sequential behaviors. Then, a probabilistic follow with content feedback model to fast discover and quantify the probabilistic follow relationship is further developed, and then, the corresponding approach to piracy prevention is designed. The extensive experimental analysis demonstrates the capability of the proposed approach.

A Physical Layer Key Negotiation Mechanism to Secure Wireless Networks

The rapid technological developments in computing technology and the proliferation of wireless network nodes with light infrastructure, have emerged large quantities of security requirements of informational privacy in cyberspace. Due to the inherent nature of open medium, diversity and variability of network topology, wireless networks are greatly difficult to secure by traditional methods. A physical layer key negotiation mechanism to secure wireless networks is proposed to quickly exchange and establish conventional cryptographic keys by exploiting the wireless channel’s characteristics. The physical layer key negotiation mechanism and its supplementary exception handling caused by the variations in communication paths are both described step by step. The simulation results verify the consistency of the keys of legitimate users, robustness and feasibility of this mechanism. Furthermore this cross-layer security technology is an exemplary complement to existing wireless network protocols to improve their security and enhances the ability to resist replay attacks, brute-force attack and eavesdropping.

Towards Optimal Lifetime in Wireless Sensor Networks for QoS Guaranteed Service Selection

Due to the efficiency and practicability, workflow has been successfully used in service-oriented Wireless Sensor Networks (WSNs). In general, Quality of Service (QoS) can be utilized to select the optimal service. However, WSNs are resource constrained, especially the energy. If we ignore the issue of limited energy, services with best QoS will consume their energy heavily and disabled earlier, which will shorten the network lifetime. Hence, in this paper, we will propose an energy efficient and QoS guaranteed service selection approach in WSNs. Through decomposing the global QoS constraints into a set of local QoS constraints, we can get a group of QoS guaranteed candidate services. Furthermore, considering of the service profile (i.e. running status, energy and QoS), we adopt fuzzy logic technique to rank the candidate services and then select the optimal one. Experimental evaluations demonstrate the capability of the proposed approach.

An Agent Collaboration-Based Data Hierarchical Caching Approach for HD Video Surveillance

In the research of networked HD video surveillance, the agent collaboration has been utilized as an emerging solution to collaborative caching in order to achieve effective adaption among the front-end HD video capture, the network data transmission and the data management for lossless video storage and complete playback. However, the cluster characteristic of various caches embedded in the IP camera, the network proxy server and the data management server, essentially contain important knowledge. How to utilize the cache clustering for collaborative stream controlling is still an open problem. In this paper, we propose an agent collaboration-based 3-level caching (AC3Caching) model, in which a cache storage space-based AP clustering mechanism is developed for fast grouping of “similar” caches on different levels. Furthermore, based on the cache cluster, transmission planning is designed based on the agent collaboration and reasoning. The experimental evaluations demonstrate the capability of the proposed approach.