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Client
Virtual X Window sessions

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# Server

The script startXvxMeta

verifies the command line arguments,

translates the arguments in corresponding configurations for the virtual X Window server xvx and the XmetaX proxy xmetax,

and starts the XmetaX proxy,

which in turn starts the virtual X Window server.

## Configuration startXvxMeta

The command

    /opt/XSOXmetaX/bin/startXvxMeta \
        [-help] \
        [-info] \
        [-dryRun] \
        [-auth file_name] \
        [:display_number_of_the_proxy [:display_number_of the_server]] \
        [screen_spezification...] \
        [configuration_statement...] \
        [-auth file_name]

starts the XmetaX proxy and the virtual X Window server with matching configurations or prints helpful informations. All arguments are optional — order is significant, though —, so that the command

    /opt/XSOXmetaX/bin/startXvxMeta

equals the following command, which shows all default values:

    /opt/XSOXmetaX/bin/startXvxMeta \
        -auth none \
        :10 :990 \
        1280x1024x8

In this case the startXvxMeta script generates the following configuration for the XmetaX proxy (Configuration of the XmetaX proxy) and — indirectly by the serverCommand statement (X Window server) — for the virtual X Window server:

    /opt/XSOXmetaX/bin/xmetax
    connection :10
    xdmcpMode query xdmcpHost localhost
    bell off extensions "X-SOFTWARE META" "X-SOFTWARE POSE" MIT-SHM SHAPE
        XInputExtension XTEST
    serverAuthorization own accessControl on
    pixmapFormats +1 +8
    metascreen metaScreen0
        visuals PseudoColor:8:8
    screen screen0
        ofMetaScreen metaScreen0
        display :990.0
        input clickTransfer on
        tags static
    serverCommand /opt/XSOXmetaX/bin/xvx :990 -screen 0 1282x1026x8

The X Window client connection (X Window client connection) as well as the X Window server connection (Screen) may be changed by additional arguments.

By default, the XmetaX proxy uses XDMCP to contact a local display manager (X Display Manager Control Protocol). Therefore, the login prompt gets displayed on the virtual X11 session usually.

The XmetaX proxy is authorized by the virtual X Window server using an automatically generated key (Authorization of the XmetaX proxy by the X Window servers).

Furthermore, a screen with the dimensions 1280×1024 and a color depth of 8 bits is defined by default.

After a click on the transferred screen, the remote user can provide input (Input source).

The configuration may be arbitrarily modified or enhanced by adding configuration statements at the end of the command line (Additional configuration of the XmetaX proxy). For instance, the following command disables XDMCP:

    /opt/XSOXmetaX/bin/startXvxMeta xdmcpMode off

The configuration options are described in the following sections.

### Printing informations

The argument

    -help

lets the startXvxMeta script print a short explanation of the command line arguments as well as the default configuration of the XmetaX proxy. Neither the Proxy nor the virtual X Window server are started.

The argument

    -dryRun

avoids execution, too: although the command line arguments are translated to configurations, only these configurations are printed.

### Authorization

The arguments

    -auth file_name|none

specify an authorization file, which is used by the XmetaX proxy for authorization of the X Window clients.

The default value none disables the authorization by keys. Though, the usual authorization by host access control remains active. Therefore, for a remote connection the corresponding hostname has to be written into the access file, usually /etc/Xdisplay_number_of_the_proxy.hosts.

For the case that the startXvxMeta script is called by a display manager (Display Manager) which automagically appends the authorization arguments to the command line, these arguments are correctly interpreted at the end of the command, too. The last -auth argument overrides all previous arguments.

### X Window client connection

The communication between the XmetaX proxy and the X Window clients uses TCP/IP, UNIX domain sockets or other local transport mechanisms. Clients connect to a certain communication port of the machine which executes the xmetax program. The port number is specified indirectly through the display number with the argument

    :display_number_of_the_proxy

The default value :10 corresponds to the port number 6010.

Since two servers cannot share a common communication port, each virtual session needs its own display number.

### X Window server connection

The second argument

    :display_number_of_the_server

indirectly specifies the port number for the communication between the XmetaX proxy and the virtual X Window server xvx. The default value is the result of the expression (1000 - display_number_of_the_proxy), hence 990, corresponding to the port number 6990, unless the display number of the proxy is specified.

Since two servers cannot share a common communication port, each virtual session needs its own display number, either specified explicitly or determined by the default subtraction expression.

### Screens

The arguments

    screen_specification...

specify dimensions and color depth of one or more virtual screens following the syntax

    width_in_pixelsxheight_in_pixelsxcolor_depth_in_bits

The color depth 8 is supported by a PseudoColor visual, the color depths 16 and 24 are supported by TrueColor visuals. One screen, 1280x1024x8, is defined by default.

### Additional configuration of the XmetaX proxy

The arguments

    configuration_statement...

are appended to the XmetaX proxy configuration initially composed by the startXvxMeta script (Configuration of the XmetaX proxy). This allows to modify the general proxy configuration as well as the configuration of individual meta screens or screens.

## Integration

### inittab

One or more virtual X11 sessions may be automatically started when the computer boots, for instance by the init process. Therefore for each session add to the configuration file /etc/inittab a line of the form

    token:levels:respawn:/opt/XSOXmetaX/bin/startXvxMeta >> /tmp/token.log 2>&1

Each line is identified by the field token, a word with usually only four characters at most (under some operating systems only two characters are significant). The field levels denotes the system runlevel(s) you want to execute the virtual X11 session.

The command

    init q

lets the init process re-read its configuration file and start the virtual X11 sessions.

### Display Manager

If you would like to integrate the virtual X11 session in an X Window environment like CDE, KDE, or Gnome, please contact <support@x-software.com> for individual instructions.

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Client
Virtual X Window sessions

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2009-12-10 19:06:25 +0100