An optimized WS-eventing for large-scale networks

Web Services are becoming more and more relevant also in the domain of embedded devices as they are becoming an important aspect of the Internet of Things. Embedded devices, especially in the field of automation, require real-time behavior. The Devices Profile for Web Services defines WS-Standards for embedded systems. The WS-Eventing is one of this standards within DPWS and enables the distributions of events. However, WS-Eventing has a scalability problem as in ad-hoc networks the notification is transmitted sequential by an event source. Under these circumstances, it is not suitable for large-scale networks with a high amount of devices. Therefore, a new approach is presented to solve this issue by acquiring helping devices. The communication is only based on unicast IP communication and thus is easy to integrate into automation infrastructures and could be established over several subnets. This approach has been investigated with an experimental setup and shows the high scalability compared to the original notification mechanism. Additionally, the real-time capability is given due to the chosen platform and real-time operating system. Thus, the new approach enables the idea of Internet of Things in automation scenarios.