The Industrial Internet of Things (IIoT) covers many computing devices and sensors constantly generating and exchanging data in a complicated network. Ongoing research tries to fit decentralized edge computing architectures in IIoT environments with urgent computation and action requirements. This paper investigates state-of-the-art edge computing applications based on security, latency, resource utilization, and energy efficiency aspects as well as application domains. Accordingly, a set of case studies for researchers and practitioners to explore or develop applications of edge structures in industrial environments are presented. It is identified that socio-technical issues related to organizations going through digital transformation can point to a possible future research area.