Configuring a Windows X Server

Alternatively to VNC, users may wish to run a Windows X Server on their local windows machine, thus enabling graphical applications to be executed from a putty session (when X forwarding is enabled).

Some of the benefits of using this method to display GUI applications includes:

• It natively uses your windows environment, so you can easily resize windows and move windows to a separate screens (if using more than one computer monitor).
• Interacting with the application may be faster and smoother, as there is no delay in moving the mouse, when compared running the application within a VNC session.

Some of the disadvantages of using this method to display GUI applications includes:

• Depending on the number of "GUI" applications and the screen size used, but it is most likely that "X Forwarding" your display to your X Windows Server will use more bandwidth.  This may perform slower over the internet.
• If the SSH session is disconnected at any time (SSH time out, computer gone to sleep or the computer is shut-down), the application is abruptly closed and you cannot resume the connection.   VNC exports a virtual desktop, whereas ssh (using X Forwarding) will run your application and shows its application windows on your computer. Therefore, VNC allows you to resume at any-time, as you are simply connecting to the "virtual" desktop.  Simply put, the the virtual desktop will continue to run, even if you are not connected to it.

It is generally recommended to use X Window forwarding, when developing models or anything else that is highly interactively.  This method of running GUI applications is not recommended for running simulations, solving problems and/or use a remote or long distance connection.

Installing a windows X Server

There are many different Windows X Server applications around, but the one recommend to use is "VcXsrc".  VcXsrc is an open source applications that is free to download and use.  To download and install the VcXsrc software, simply follow these instructions:

• Download VcXsrv from http://sourceforge.net/projects/vcxsrv/files/latest/download?source=files

• Click on the Save File button.
• Once the installer has downloaded, simply run the installer

• Simply click on the Next button

• Click on the "Install" button to begin the install process.  The program will take a minute or two to install

• Once the installation has completed, click on the Close button

The installer should have installed a "VcXsrc" application to your desktop.  Double click on the icon to start the X Server.  You won't see anything "pop up", but you may notice VcXsrc running in the lower right hand side of the Taskbar.

Configuring Putty to enable X Forwarding

Once the X Windows Server is running, you will need to configure your "putty" session to enable "X11 forwarding".  To do this:

• Start Putty
• If you have already a saved "Session", select the appropriate session and click on the load button (an example can be seen in the screen shot below).

• Once the the session is load, select the Putty Category Connection -> SSH -> X11, as can be seen in the screen shot below.

• Click on the "Enable X11 Forwarding" check box.
• It is also advised to enable "compression", has it will decrease the amount for bandwidth required.  To do this, select the Putty Category Connection -> SSH and tick the "Enable compression" check box, as displayed in the image below

• Once options have been enabled, go back to your "session" within Putty, then click the save button, as this will save the X Forwarding and compression options for future use.
• Connecting to the HPC system and starting a GUI application.
• Double click on your save session to connect to the HPC session.

• You will notice a SSH session has been established.  Simply execute any application command (matlab as an example) and it should open as a separate window within your windows environment.

Select different VcXsrc Display Settings

There are some applications, such as ABAQUS, that will not work using the default "Multiple windows" display setting.

To use a different VcXsrc Display Settings, simply:

• Close any  VcXsrc sessions currently running.
• Run the XLaunch application - there should have been a desktop icon provided when application was installed.
• Select an alternative VcXsrc Display Settings option, such as "One Large Window", as can be seen the image below.

• Then click on the next button a few times (no other options are required to change) until you have finished.
• This will then start a Windows X Server in a different mode and should allow GUI applications to be display on your local machine.