30

[root]# xhost +localhost

localhost being added to access control list

[root]# su tomcat

bash$ mathematica

bash$

This  is  not  a  good  technique  since  there  is  a  potential for  security  problems,  these  are  probably limited  since  it is

only connections from the same machine. Another problem is that every time the front end is used, a window will be

drawn on the screen, which may be annoying to a user of the system.

A more satisfactory alternative is to run a virtual X server, such as 

Xvnc

.

Xvfb

Xvfb  is  a  virtual  frame  buffer  server  described  at  http://www.xfree86.org/4.3.0/Xvfb.1.html.  It  can  be  used  as  an

alternative to Xvnc, but typically we have found Xvnc to be easier to use and provide more functionality.

For Linux, you can download an RPM archive from http://www.redhat.com. After installation, you can launch it as

follows (you will probably run this as root).

su tomcat  c "/usr/X11R6/bin/Xvfb :1  fp 

unix/:7100,/usr/local/Wolfram/Mathematica/4.2/SystemFiles/Fonts/Typ

e1,

/usr/local/Wolfram/Mathematica/4.2/SystemFiles/Fonts/BDF   screen 0 

800x600x24 " &

This command launches Xvfb referencing a font server on port 7100 and adding directories that contain the Mathe 

matica fonts. Note that if you install Mathematica in some alternative location, you should modify these directories.

Under some Mathematica installations  the location  of Mathematica fonts is added  to the font server configuration;

in  this  case  the  Mathematica  fonts  do  not  need  to  be  referenced  when  Xvfb  is  launched.  Xvfb  could  then  be

launched as shown here.

su tomcat  c "/usr/X11R6/bin/Xvfb :1  fp unix/:7100" &

In these examples, Xvfb expects to use port 7100 on the local machine for the font server. The actual setting may

need to be modified  if some alternative  configuration of  font server is used.  For example, under  Redhat 6 the font

server uses a local unix socket and Xvfb should be launched as follows.

su tomcat  c "/usr/X11R6/bin/Xvfb :1  fp 

unix/: 1,/usr/local/Wolfram/Mathematica/4.2/SystemFiles/Fonts/Type1

,

/usr/local/Wolfram/Mathematica/4.2/SystemFiles/Fonts/BDF   screen 0 

800x600x24 " &

If you are not running a font server, you may need to launch Xvfb with no font server reference. In this case, it may

be  necessary  to  copy  the  Mathematica  fonts  into  the  X  distribution  layout  as  described  in  the  section  below  on

manual font installation.

 .