Current Internet of Things (IoT) development requires service distribution over Wireless Sensor and Actor Networks (WSAN) to deal with the drastic increasing of network management complexity. Because of the specific constraints of WSAN, centralized approaches are strongly limited. Multi-hop communication used by WSAN introduces transmission latency, packet errors, router congestion and security issues. As it uses local services, a decentralized service model avoid long path communications between nodes and applications. But the main issue is then to have such local services installed on the desired nodes. Environment Monitoring and Management Agent (EMMA) system proposes a set of software to deploy and to execute such services over Wireless Sensor and Actor Networks (WSAN) through a middleware based on Resource Oriented Architecture (ROA). Its Internet integration and the local management of data heterogeneity are facilitated through the use of current standard protocols such as IPv6 LoW Power Wireless Area Networks (6LoWPAN) and Constrained Application Protocol (CoAP). This contribution presents EMMA middleware, methodology and tools used to determine efficient service mapping and its deployment.