This page describes the downloadable server
extensions available for the ViewStation's server.
Integral
X11 Server Extensions
The HDS ViewStation server software contains a number of built-in
X11 server extensions. These are software modules that allow the server
to do special functions which are not necessary for the standard X11
server functionality, but operate as optional extensions. One example of
an extension of this type is the Shape extension, which allows the
server to draw a round window, such as the window used for the "oclock"
client application. The X utility program, xdpyinfo, shows what
extensions are available for the active display. Check the HDSware
version for the extensions currently supported.
Downloadable X11 Server Extensions
There are some
additional extensions that are not built in but are available for the
server to download from the HDSware location on the network. There are
four extensions of this type included on the HDSware tape, the XTrap
extension, the Multi-Buffering extension, the Shared Memory extension,
and the PEX 3-D drawing extension.
Loading the X11 Server
Extensions
These can be used by loading them into the server
code with entries in the clients.config file (in the default
configuration, these clients are commented out of this file). You can
load them by removing the comment characters in this file as you would
one of the HDSperx clients and the extension will be loaded with the
server code.
You should note that these extensions are installed as an
integral part of the server code, not as independent clients. For this
reason, you should always be careful to match the server code version
with the extension files on the same HDSware tape. If you mix different
file versions, they won't work. This is not generally a problem, since
the extension files are included on the same tape; you just have to be
careful not to mix tape sources.
XTrap Extension
The XTrap extension is used to test the operation of the X server
and X software, typically with third party software testing application
programs. It is often used with scripts that capture keypresses and
mouse movements, or replay scripts to simulate sessions with user and
application interaction. The XTest extension is part of the XTrap
extension, though it is often installed separately. Refer to the X11
manual pages for a more complete specification.
Multi-Buffering
Extension
The Multi-Buffering extension is used to enhance the display of
graphics images. The displayed image is swapped for another buffered
image which was drawn while it was off-screen, thus giving a fast
replacement with the actual drawing invisible to the viewer. Refer to
the X11 man pages for more detail.
Shared Memory Extension
The Shared Memory extension is used to provide local downloaded
clients with a mechanism to use high performance direct shared memory
access for X pixmaps. This extension is loaded by default (refer to the
clients.config file).
PEX-3D Extension
The PEX-3D extension is a 3D Protocol extension to the X Window
System. It adds over 200 X protocol requests for defining and
displaying 3D pictures.
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