In this chapter, we present a service-oriented architecture designed for the use of wireless sensors networks (WSNs) in industrial applications such as the operation and maintenance of industrial installations. This architecture comprises the OCARI wireless sensor network and the OPC-UA/ROSA middleware, as well as the KASEM predictive maintenance system. In contrast to well-known communication stacks for wireless sensor networks such as ZigBee and WirelessHart, OCARI has been designed to support mobility of sensor nodes. Furthermore, the OPC-UA/ROSA middleware provides service discovery to enable the interconnection of the WSN with the Internet of Things (IoT). This architecture targets various industrial applications such as process monitoring, pollutant detection, monitoring of fuel storage area, fire detection in temporary worksites, health monitoring of people working in hazardous conditions, etc.