Abstract
Recent years have seen a rising demand in integrating real world information into existing applications and business processes. The Internet of Things (IoT), which is based on networked embedded devices such as passive and active Radio-frequency identification (RFID) tags, wireless sensor nodes, etc. plays a key role in providing the link to the physical world. Efficient integration of the IoT into Internet of Services is considered as a major challenge, mainly due to the heterogeneity of the existing IoT solutions. The prevalence of IPv6 over Low power Wireless Personal Area Networks (6LoWPAN) has enabled sensor nodes to communicate using Internet technologies and services. While the integration of the Internet Protocol (IP) into wireless sensor networks brings huge opportunities to provide Internet and Web based communications and interactions with other networks, the power, network and resource constraints of the sensor nodes and wireless sensor networks pose major challenges to adopting IP-based solutions in wireless sensor networks. Service Oriented is a well-established architecture and has been successfully used for many years on the Internet. Service Oriented Architecture (SOA) and the web services provide interoperability and reusability of software components and enabling the design of distributed and loosely coupled systems that are supported by multiple platforms. Using service oriented interactions over wireless sensor networks can enable seamless integration of the data and functionalities that are provided by these networks. Using service oriented architecture, the data and functionalities of wireless sensor nodes and networks can be represented as a service to the Internet and Web. The services can also be used for managing and monitoring the networks. This will create a huge potential for interaction and integration of the wireless sensor network enabled services into the Web. This thesis describes the design and development of a flexible and efficient Web service Architecture for wireless sensor networks. The research has developed an energy efficient and adaptable discovery mechanism for ad hoc and dynamic wireless sensor networks. Our proposed solution is based on the IP protocol suite and takes into account the inherent resource limitation of wireless sensor networks. Our solutions support both SOAP and RESTful services in an integrated framework and can interact with different types of services on the Web and enterprise systems. We also provide solutions for service discovery that uses a reinforcement learning technique to improve the performance of the service discovery process according to the dynamicity of the network. The work is implemented and evaluated on a wireless sensor test-bed accompanied by a demonstrator application to represent the functionality of the proposed solutions. The evaluation results show that the proposed solutions can significantly reduce the payload and size of the service discovery message in service communications up to 94% compared with the traditional service oriented solutions over the Web. The proposed service discovery mechanisms improve the power and communication efficiency by decreasing size of the service discovery messages and the process overload by up to 25%. The proposed solutions can co-operate with other solutions such as Constrained Application Protocol (CoAP); however the discovery and service communication solutions significantly reduce the messaging overload and can enhance CoAP or other SOAP based services. The discovery process can also be used with SOAP and CoAP (i.e. RESTful) services and enables efficient discovery solutions for the services in dynamic wireless sensor networks.