The Arrowhead framework enables interoperability and integrability for new and legacy systems by applying Service Oriented Architecture (SOA) principles at the Industrial Internet of Things (IIoT) domain. The core systems of Arrowhead provide service registration, discovery, security and other services for application systems within the System of Systems domain under their authority. While the application systems can communicate with each other using any protocol that fits them, the core Arrowhead services have been available as RESTful HTTP implementation only. This practically meant that those application systems without built-in HTTP protocol support, must have used translators to connect to the Arrowhead services. The current paper describes a pragmatic enhancement for OPC Unified Architecture (OPC UA) endpoints, so they are now able to utilize Arrowhead core services natively. Moreover, the paper provides a solution for IEC 61499 Programmable Logic Controller (PLC) integration, and a practical use case description as proof of concept.