## 1 Introduction
They monitor the changes, detect failure or degradation of performance, begin diagnostic procedures, and conduct preventive, corrective and proactive actions [11]. However, in the case of maintaining dynamic interoperability, the monitoring of these functionalities is not a simple task. Mainly because the dynamic and unpredictable changes of a WSN's status cannot be represented using a linear cause-effect approach. For instance, usually if a node has a low level of energy, the action could be to \"sleep\" this node. But if this node is interoperating in an emergency situation (e.g. natural disaster, terrorist attack), then it must continue sensing and transmitting data instead of sleeping. This reasoning process of monitoring and adaptation needs to be _contextualised_ because it depends on the context inside which the sensing is carried out [12]. Therefore, our research premise is the existence of different contexts, both at in-network and data repository levels, which play an important role in the dynamic interoperability of WSNs. From a pragmatic point of view, the dynamic interoperability of WSNs at different periods of time can be maintained by using a set of metadata elements in order to provide a description of observations, processes and functionalities, as well as their current configuration that can enable the understanding of a network itself [13-15]. Metadata are the common thread that can connect all the status and functionalities of WSNs as well as preserve the context of the sensing data [16,13]. This paper describes the development of a context model based on metadata elements for maintaining the dynamic interoperability of WSNs. The reasoning process to contextualise the dynamic interoperability of WSNs using metadata elements is carried out by two types of reasoning rules. One of them, the contextualising rule, is introduced in the scope of our research to identify different WSN status according to a specific context using metadata elements. The other type, called bridge rules, was previously introduced by [PERSON] [12], and it is used to represent the relationship between contexts and the dynamic interoperability. It is important to point out that previous developed context models have mainly considered sensors as a mechanism to capture information about the context itself [17]. In contrast, this paper proposes a model focused on a context decision-making representation about how to maintain the sensor dynamic interoperability instead of only handling the WSN status changes. The next section describes the concept of metadata and their principal requirements in the scope of WSNs. Section 3 describes what notion of context has been envisaged and why contexts are needed to reason about the WSN status changes in order to maintain the dynamic interoperability. The developed context model and the relevant aspects of its representation are discussed in Section 4. Furthermore, Section 5 describes the reasoning mechanisms of inferring and connecting contexts by providing examples of contextualising rules. Section 6 provides a discussion about the impact of the context model in WSN interoperability by providing examples of bridge rules. Finally, the main conclusions are summarised in Section 7.