UGP provides users the ability to run interactive GUI applications on the cluster compute nodes and to interact with these applications via their web browsers. UGP impliments this by using VNC, a program that allows users to interact with interactive programs accross the network. To use VNC, UGP runs the VNC Server on the cluster compute node as the user and the VNC Viewer applet in the users web browser. All the tasks normally required to run VNC, such as the generation of a VNC password for the user, the creation of a VNC startup file, etc., are taken care of for the user by UGP.
The following is the steps when the user runs xterm in the browser:
- Runs the VNC Server as the user on the cluster compute node. It does this by using Globus GRAM to start up a fork job on the Grid Appliance conected to the cluster. The fork job, SSHs to the compute node where it starts up the VNC Server. As part of starting up the VNC Server, UGP generates a random password for VNC, and places all necessary files in a subdirectory of the .vnc directory under the user’s login id.
- Runs the VNC Viewer Applet in the user’s web browser, passing it the VNC password and a port and address that it is to use to communicate with the VNC Server.