  Wireless sensor networks have been a driving force of the Industrial Internet
of Things (IIoT) advancement in the process control and manufacturing industry.
The emergence of IIoT opens great potential for the ubiquitous field device
connectivity and manageability with an integrated and standardized architecture
from low-level device operations to high-level data-centric application
interactions. This technological development requires software definability in
the key architectural elements of IIoT, including wireless field devices, IIoT
gateways, network infrastructure, and IIoT sensor cloud services. In this
paper, a novel software-defined IIoT (SD-IIoT) is proposed in order to solve
essential challenges in a holistic IIoT system, such as reliability, security,
timeliness scalability, and quality of service (QoS). A new IIoT system
architecture is proposed based on the latest networking technologies such as
WirelessHART, WebSocket, IETF constrained application protocol (CoAP) and
software-defined networking (SDN). A new scheme based on CoAP and SDN is
proposed to solve the QoS issues. Computer experiments in a case study are
implemented to show the effectiveness of the proposed system architecture.
