A page that uses JSON, JavaScript and HTTP to call methods on an OPC UA server.

This page uses JavaScript to construct a JSON call request and HTTPS to POST it to the OPC UA ReferenceServer. The same methods can be called by any OPC UA Client using TCP and the binary data encoding. The parameters in the Call requests and responses are defined here.

The following figure illustrates the interactions between the website and the OPC UA ReferenceServer:

Call Sequence Diagram

Restrictions on cross-site scripting require the web server to forward requests to the HTTP endpoint exposed by the OPC UA ReferenceServer.

A BadUserIdentityToken rejected error will appear if not logged in. The access token is sent to the server as the Authorization header in the HTTP request.