HP-UX 11i June 2002 Release Notes

Internet and Networking Services
Low Bandwidth X Extension (LBX)
Chapter 12
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Low Bandwidth X Extension (LBX)
The Low Bandwidth X extension (LBX) uses several compression and local caching
techniques to improve performance on wide-area networks and on slower speed
connections. These techniques reduce the amount of protocol data transported over the
network and reduce the number of client-to-server round trips required for common
application startup operations.
LBX is implemented in two pieces: an X server extension and a proxy application. The X
server extension provides the new optimized protocol. The proxy application, lbxproxy,
translates a normal client X protocol stream into an LBX stream. This permits any
existing application to gain the benefit of the optimized protocol with no changes. The
proxy is especially useful when multiple applications are running on the same local area
network separated from the X server by a slower network. In this case, the full benefit of
the local cache is shared by each application using the same proxy process.
The lbxproxy binary has been added to the /usr/bin/X11 directory. It must be started
by an end user either directly or through the Proxy Manager (proxymngr) and Find
Proxy (xfindproxy).
Performance Issues
When X clients are separated from the X server by a slow connection such as a modem,
performance will be improved by going through lbxproxy. However, when the client and
X server are separated by a fast connection such as a local area network, performance
may be degraded by running through lbxproxy.
Proxy Manager (proxymngr)
The Proxy Management Protocol is an ICE-based protocol that provides a way for
application servers to easily locate proxy services such as the LBX proxy. (LBX is
currently the only supported proxy service.)
Typically, a service called a “proxy manager” is responsible for resolving requests for
proxy services, starting new proxies when appropriate, and keeping track of the
available proxy services. The proxy manager strives to re-use existing proxy processes
whenever possible.
The proxymngr executable has been added to the /usr/bin/X11 directory. It must be
started directly by the user. The proxymngr executable can also be used in conjunction
with xfindproxy, which is also in /usr/bin/X11.
Remote Execution (RX) Service
The remote execution (RX) service specifies a MIME format for invoking applications
remotely (for example, via a Web browser). This RX format specifies a syntax for listing
network services required by the application (for example, an X display server). The
requesting Web browser must identify specific instances of the services in the request to
invoke the application.
There are two methods to demonstrate this service:
1. xrx (the helper program)