OPC UA is a platform-independent standard through which various systems and devices communicate by sending request and response Messages between Clients and Servers or Network Messages between Publishers and Subscribers over supported network types such as HTTPS and HTTP.
In the OPC UA Client-Server model, a set of Services acts as the interface between Clients and Servers. Object information from the Server that is made available to the Client is called the Address Space and is exposed in formats such as XML and JSON.
The basic component of the Address Space is a Node, that contains values or references to other nodes. The referenced nodes represent the hierarchy structure.
The OPC UA Agents allow you to traverse the Server Address Space represented by Branches and to include nodes as tags in your Data Stream, using the OPC UA Client-Server model to connect to an OPC UA Server endpoint.
In order to retrieve and publish Tag values on the OPC UA Server, the Nodes should have the proper Read and Write configuration on the OPC UA Server.