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fioricet no online prescription The LBX Mini-HOWTO Paul D. Smith, psmith@baynetworks.com v1.04, 11 December 1997 LBX (Low Bandwidth X) is an X server extension which performs compres sion on the X prot fioricet no online prescription col. It is meant to be used in conjunction with X applications and an X server which are separated by a slow network connection, to improve display and response time. ___ fioricet no online prescription __________________________________________________________________ Table of Contents 1. Introduction 2. What's The Status Of LBX? 3. Who Can Benefit From LBX? 4. Who Doe fioricet no online prescription n't Need LBX? 5. How Does LBX Work? 6. What Do I Need To Use LBX? 7. What Don't I Need To Use LBX? 8. How Do I Start LBX? 9. Problems 10. Documentation 11. Alternative fioricet no online prescription 11.1 dxpc - The Differential X Protocol Compressor 11.1.1 Advantages 11.1.2 Disadvantages 11.1.3 Where Can I Get dxpc? 11.2 Ssh (Secure Shell) fioricet no online prescription 11.3 Which Is Better? ______________________________________________________________________ 1. Introduction Low-Bandwidth X (LBX) attempts to recognize that in this da fioricet no online prescription and age, not everyone will be a fast LAN hop or two away from the system that they are running their applications on. The X protocol can generate an extraordinary amount fioricet no online prescription f traffic, especially for simple-seeming things such as creating new windows. As anyone who has tried to use X over a dial-in modem at 28.8 or even higher can attest, cre fioricet no online prescription ting new X windows can involve an excruciating wait. LBX is fundamentally a compression and caching scheme designed to minimize the amount of X traffic generated between t fioricet no online prescription o systems. 2. What's The Status Of LBX? As of the X Consortium's release of X11R6.3 in December, 1996, LBX is a full extension to the X protocol. For XFree86 folks, that fioricet no online prescription s XFree86 version 3.3. 3. Who Can Benefit From LBX? If you use a modem to dial into a service provider, then run X applications on remote machines with their DISPLAYs se fioricet no online prescription to your local machine (or vice versa), LBX will speed up that connection. Also if you set DISPLAYs from systems across WANs (other countries, for example) or other slow fioricet no online prescription inks, LBX can help. 4. Who Doesn't Need LBX? LBX is useless, of course, if you're only running applications locally, or if you're not running X at all. Also, if you're r fioricet no online prescription nning on a fast LAN, LBX won't be much help. Some people say "if LBX cuts down on network traffic, wouldn't it be good to use even on fast LANs?" It might be, if your goa fioricet no online prescription is to reduce network traffic. But if your goal is to get better response time LBX probably isn't what you want. Although it does introduce caching and compression, that fioricet no online prescription comes at a cost on both ends (extra memory for caching, and extra CPU for decompression). If your link is fairly speedy LBX will probably result in an overall slowdown. 5 fioricet no online prescription How Does LBX Work? LBX works by introducing a proxy server at the client side, which performs caching and compression. The X server knows that the client is using a pro fioricet no online prescription y server, and decompresses accordingly. Here's a normal setup for remote X clients. In our discussion, LOCAL is always the workstation sitting in front of you, whose monit fioricet no online prescription r you're looking at, and REMOTE is the remote workstation, where the actual application is running. __________________________________________________________________ fioricet no online prescription ___ REMOTE LOCAL +-----+ +-----+ | APP |-\ Network +--- fioricet no online prescription ------+ | |\ +-----+ \--------------------------->| X SERVER |=>| || +-----+ / (X Protocol) +----------+ +-----+\ | APP |-/ fioricet no online prescription /_____// +-----+ ______________________________________________________________________ When using LBX, a proxy server (lbx fioricet no online prescription roxy) is introduced on the remote side, and the applications talk to that process instead of directly to the LOCAL server. That process then performs the caching and comp fioricet no online prescription ession of X requests and forwards them. It looks like this: ______________________________________________________________________ REMOTE fioricet no online prescription LOCAL +-----+ +-----+ +-------+ Network +----------+ | |\ | APP |->| fioricet no online prescription PROXY |----------------------------->| X SERVER |=>| || +-----+ +-------+ (LBX/X Protocol) +----------+ +-----+\ +-----+ / fioricet no online prescription /_____// | APP |--/ +-----+ ______________________________________________________________________ Details on exactly what caching and compression fioricet no online prescription BX does is beyond the scope of this document. 6. What Do I Need To Use LBX? You need an X server on your LOCAL system which has the LBX extension compiled in. Unless yo fioricet no online prescription explicitly told it not to when building it, X11R6.3 servers automatically enable LBX. Also, all XFree86 3.3 servers have LBX enabled by default. You can use the xdpyinfo fioricet no online prescription command to see if your server has the LBX extension: run xdpyinfo and look at the list just under "number of extensions"; you should see "LBX" listed there. Next, you need fioricet no online prescription to get an lbxproxy program compiled for the REMOTE system. This is the tricky part. If the remote system is not the same type as your local system, the lbxproxy on your l fioricet no online prescription cal system will do you no good, of course. There is unfortunately no "broken out" distribution of lbxproxy, so you will have to either (a) get and build most, if not all, fioricet no online prescription f X11R6.3 for the remote system, or (b) find someplace to get a pre-compiled lbxproxy binary for your system. The latter is much simpler of course. The lbxproxy is simpl fioricet no online prescription a single executable. There are no configuration files, resource files, etc. associated with it. 7. What Don't I Need To Use LBX? The REMOTE system does not need a new X fioricet no online prescription server (as always, the REMOTE system doesn't need any X server running). The application you want to run does not need to be linked with any special version of X, or any s fioricet no online prescription ecial libraries; I regularly use commercial X11R5 apps over LBX with no trouble. You do not need root or other privileged access on the REMOTE system; the lbxproxy process fioricet no online prescription runs under your normal access permissions. Further, you can run it right from your home directory: it does not have to be installed anywhere. 8. How Do I Start LBX? OK, fioricet no online prescription ere it is... after all that it's actually quite simple. Replace LOCAL and REMOTE below with the hostnames of your local workstation and remote system, respectively (don't fioricet no online prescription et them mixed up!) On LOCAL: 1. Start your X server. 2. Tell your X server that the remote system is allowed access. Using the host-list method, type xhost +REMOTE. fioricet no online prescription f you use xauth you may need to do more than this; see the xauth(1) man page for more information. You should consult the Remote X Apps Mini-HOWTO if you're not familiar with remote X access permission setup. On REMOTE: 1. Start lbxproxy and tell it to forward to the LOCAL X server, l fioricet no online prescription ke this: $ lbxproxy -display LOCAL:0 :1 & This tells lbxproxy to use display :1 on the REMOTE system; if that system has >1 display already you can use :2 or wh fioricet no online prescription tever instead. 2. Set your DISPLAY environment variable to point to the display that lbxproxy is providing, instead of the normal display: $ DISPLAY=:1 $ fioricet no online prescription export DISPLAY Or, if you use csh or clones: % setenv DISPLAY :1 3. If you're using xauth you will need to ensure that your cookie is available locally. See th fioricet no online prescription Remote X Apps Mini-HOWTO for more information on this. 4. Start your X applications! That's it; all X apps that are start fioricet no online prescription d up pointing to :1 will use LBX. Of course, there's no reason you couldn't also start X apps pointing to LOCAL:0 and have both running at the same time. 9. Problems Her fioricet no online prescription are some common problems: Q) lbxproxy exits with an "access denied" error. A) This means the LOCAL system isn't accepting connections from the REMOTE system d fioricet no online prescription e to permissions errors. See the Remote X Apps Mini-HOWTO for details on these issues. As a simple trouble-sho fioricet no online prescription ting measure, try running a simple X app like xclock on REMOTE and have it display on the local system without using lbxproxy: $ xclock -display LOCA fioricet no online prescription :0 If that doesn't work, it's xhost or some other basic X problem, not LBX. 10. Documentation The only documentation available in a standard X distribution may be the lbxproxy(1) man page. If you have access to the X source tree, then very interesting information on LBX is available there: · xc/doc/specs/Xext/lbx.mif (Framemaker MIF) · xc/doc/hardcopy/Xext/lbx.PS.Z (Compressed Postscript) · xc/doc/hardcopy/Xext/lbxTOC.html (HTML) More detailed discussion of specific LBX algorithms is available here: · xc/doc/specs/Xext/lbxalg.mif (Framemaker MIF) · xc/doc/specs/Xext/lbxalg.PS.Z (Compressed Postscript) If you don't have access to the X11 source, you can obtain these files from the X Consortium's FTP site . 11. Alternatives If you don't like lbxproxy for some reason: you're not satisfied with the performance, it doesn't work for you, you don't want to hassle with creating an lbxproxy for the remote host, or you simply are interested in trying other options, there is at least one other package for X protocol compression (anyone have others?) 11.1. dxpc - The Differential X Protocol Compressor · Original Author: Brian Pane · Current Maintainer: Zachary Vonler dxpc works in essentially the same way as LBX. However, to avoid having to implement an X extension and modify the X server code, dxpc uses two proxies: one that runs on the REMOTE host, like lbxproxy, and one that runs on the LOCAL host. The REMOTE host proxy communicates between the X clients and the LOCAL host proxy, and the LOCAL host proxy communicates between the X server and the REMOTE host proxy. So, to both the X clients and
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