## 4 Emergent Configurations in the IIoT
### Administration of SDN-Based Ubiquitous Computing-Aided EC in Oil and Gas Explorations
#### 4.4.1 Overview of SDN Architecture in Wireless Network Applications  
As a result of the resource-constrained limitations of existing traditional network infrastructures due to pre-programmed application-specific integrated circuits, there is need to develop flexible network architectures that will efficiently adapt to changes in network conditions and operations in order to perform a dedicated task. Consequently, the SDN architecture is proposed in [70] where network control is decoupled from the conventional hardware devices [4]. In other words, the data plane (also known as forwarding plane) which is responsible for forwarding packets/frames from a given interface to another is separated from the control plane that is usually designed to manage network operations for decision-making procedures on traffic directions. The SDN technology is designed to consist of three distinct layers including infrastructure, control and application layers, where all the information housed in the data plane (infrastructure layer) are centrally managed and directed by the control plane. The application layer consists of network applications that are deployed for managing the technical configuration of network devices while the control layer (control plane) fundamentally consist of one or a given combination of SDN controllers that may otherwise be described as the wholistic brain of the entire SDN architectural system. Application program interfaces (API) are often used for interfacing (or interacting) between the layers of the SDN structure and may be classified into four groups including northbound API, southbound API, east and westbound API respectively. The communication between the application and control layer is interfaced by the northbound API while the southbound API is required for communication between the control and infrastructure layers as depicted in Figure 6. Network communication protocols such as OpenFlow protocol are good examples of southbound API which is often conventionally deployed in SDN-based networks for interaction between the control plane and the infrastructure layer. Finally, the east and westbound API are used as network interfaces between controllers especially when multiple controllers are engaged for enhancing communication performance in the software-defined network. A few examples of open-source controllers for enabling SDN include OpenDaylight, Nox/Pox, Cherry, ONOS, OpenKilda and RUNOS etc. 4.2 Description of Ubiquitous Computing-enabled SDN-based Architecture of EC for Maritime Operations  
Ubiquitous computing (or simply \"Ubicom\") is simply described as a paradigm where computing can be made by various device users in any given location and at any given time. The user in this context is described to interact with the computer which could either be desktop computers, laptops, electronic hardware, and terminals that are incorporated into everyday objects such as a pair of eye glasses, curtains, windows, doors and fridges. etc. This paradigm also known as _ambient intelligence_ or _pervasive computing_ is supported by some fundamental IoT enabling technologies such as sensors, actuators, microprocessors, internet connectivity and numerous specialised application layer protocols. Motivated by the works done in [62; 71], we propose an EC architecture for monitoring the operations of nautical explorations as illustrated in Figure 7 in such a way that the onshore marine users exploit the benefits of ubiquitous computing and SDN technology in order to satisfy user standards. In this architecture, the interaction between the seashore located marine user (i.e., UA) and an ECM is managed by an efficient _ubiquitous computing service system_ (UCSS) that is based on _matchmaking_ and _rule-based_ algorithms, where the UA of the EC network tries to exchange dynamic information to perform network diagnosis and high-quality evaluations for the improving the communication efficiency and throughput of the entire marine networks.