The App URI in the ThingWorx Remote Thing Tunnel configuration specifies the endpoint of the specified tunnel. The default value (/Thingworx/tunnel/vnc.jsp) will point to the built in ThingWorx VNC client that can be downloaded through the Remote Access Widget in a Mashup to provide VNC remote desktop access. Leaving the App URI blank will result in the Tunnel being connected to the listen port on the users machine as specified in the Remote Access Widget. In this case the user must supply the application client (e.g. an ssh client) in order to connect to the tunnel endpoint.