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Caudium HOWTO
David Gourdelier
Caudium Group
  vida at caudium dot net
Copyright © 2002 by The Caudium Group.
September 2002
Revision History
Revision 2.2 2002-09-20 Revised by: dg
Few more fixes, document now contains images and icons. See revision history
for more information.
Revision 2.1 2002-06-14 Revised by: dg
Document is now well-formed XML, one more example. See revision history for
more information.
Revision 2.0 2002-06-14 Revised by: Tab
Converted to DocBook XML 4.1.2. See revision history for more information.
Revision 1.0 2002-06-06 Revised by: dg
Initial release
Revision 0.91
Indentation of the SGML document and one more paragraph. See revision history
for more.
Revision 0.9
This Howto is going into stable state. See the revision history for more
information.
Revision 0.05 2002-04-04
This HOWTO is in the DocBook format. See the revision history for more
information.
Revision 0.04
Added Introduction and license. See the revision history for more
information.
Revision 0.03
Added some useful corrections. See the revision history for more information.
Revision 0.02
Minor correction in other answers. See the revision history for more
information.
Revision 0.01 2002-03-11
Initial revision. See the revision history for more information.
This is the Caudium HOWTO. This document will give an overview of the
Caudium server. New users will learn how to set a basic virtual server up.
More experienced users will find useful tips on development and optimization.
Finally at the end I give some documentation on Caudium top priorities for
people who want to contribute.
-----------------------------------------------------------------------------
Table of Contents
1. License
2. Overview
2.1. What is Caudium?
2.2. Caudium vs Roxen: Why a fork?
2.3. Comparing Caudium with Apache
2.4. Advantages of Caudium
2.5. Disadvantages of Caudium
3. Getting packages
3.1. How to get packages for Debian GNU/Linux
3.2. How to get packages for FreeBSD
3.3. How to get packages for Solaris
3.4. How to get CAMAS from CVS/source
4. Creating your first server
4.1. Installing Caudium from sources
4.2. Starting
4.3. Stopping from command line
4.4. Directory organization
4.5. Upgrading Caudium
4.6. Configuration InterFace (CIF.)
4.7. Adding your first server
5. Customizing your server
5.1. How to run Caudium as a non-privileged user; How to secure Caudium
5.2. How to benchmark a web server
5.3. How to tune your system for best Caudium performances
5.4. How to use your own fonts
5.5. How to get UltraLog working
6. Developing with Caudium
6.1. Your first RXML file
6.2. The Pike tag
6.3. Your first Pike script
6.4. Your first module
6.5. How to use a backtrace
6.6. How to print something to debug log file
7. How to help the Caudium community
7.1. How to promote Caudium
7.2. How to write documentation
7.3. How to get a CVS account
7.4. How to test Caudium
7.5. How to send a bug report
8. Revision History/Credits/The End
8.1. Revision History
8.2. Credits and contributors
8.3. The End
A. GNU Free Documentation License
A.1. PREAMBLE
A.2. APPLICABILITY AND DEFINITIONS
A.3. VERBATIM COPYING
A.4. COPYING IN QUANTITY
A.5. MODIFICATIONS
A.6. COMBINING DOCUMENTS
A.7. COLLECTIONS OF DOCUMENTS
A.8. AGGREGATION WITH INDEPENDENT WORKS
A.9. TRANSLATION
A.10. TERMINATION
A.11. FUTURE REVISIONS OF THIS LICENSE
A.12. How to use this License for your documents
List of Figures
4-1. Ports in the CIF
4-2. Filesystem in the CIF
4-3. Example of output
List of Examples
4-1. Your user filesystem.
4-2. A simple virtual hosting regular expression.
4-3. A better and quicker regular expression.
6-1. Some simple RXML tags.
6-2. The PHP documentation as a Pike tag.
6-3. A basic Pike script.
6-4. A real world script.
6-5. A script for the power user.
6-6. A sample module.
-----------------------------------------------------------------------------
Chapter 1. License
Permission is granted to copy, distribute and/or modify this document under
the terms of the [http://www.gnu.org/copyleft/fdl.html#SEC1] GNU Free
Documentation License, Version 1.1 or any later version published as by the
Free Software Foundation; with no Invariant Sections, with no Front-Cover
Texts, and with no Back-Cover Texts. A copy of the license can be found in
Appendix A.
This document is a volunteer effort. Feel free to improve and make changes.
If you catch any mistakes, please correct them.
-----------------------------------------------------------------------------
Chapter 2. Overview
2.1. What is Caudium?
Caudium is a Web server based on a fork of the [http://www.roxen.com/]
Roxen Challenger 1.3 WebServer. Like Roxen, Caudium is written in [http://
pike.roxen.com/] Pike with parts written in C for performance reasons. Pike
is an interpreted language developed by Frederik Hübinette and Roxen Internet
Software (RIS), a Swedish company which also created the Roxen Web Server.
Caudium, like Pike, is distributed under the terms of the GPL license;
several companies and people are involved in its development.
Caudium features include:
  *  Single-process architecture.
  *  Optional multi-threaded mode.
  *  Backwards compatible with Roxen 1.3 on the API and RXML level.
  *  Runs on many Unix-like systems (GNU/Linux, FreeBSD, OpenBSD, NetBSD,
Solaris, AIX, Darwin/MacOS X).
  *  Web based interface for easy administration.
  *  Built in SSL capabilities. Enabling SSL on Caudium is as easy as filing
a web form.
  *  Written in Pike. Unlike most web servers, you don't need to learn C or
C++ and those pesky details like memory allocation to enhance the
server's capabilities.
  *  Extensible with custom modules.
  *  Powerful API.
  *  Lots of standard modules distributed with the server, including an FTP
server, the CAMAS web mail application, and the UltraLog log analysis
tool. The "module" directory in Caudium 1.2 with CAMAS contains 192
code-only files. Most of the modules are in a single file.
  *  RXML language. RXML stands for Roxen eXtensible Markup Language and is
a set of tags, containers and simple programming language constructs that
you put in your HTML source. Those tags and containers will be
interpreted at run-time by Caudium. This allows non-programmers to do
development.
  *  XML language. Using Sablotron, Caudium can render XML pages processed
with XSLT, DOM and XPath. You can find more information on Sablotron on
[http://www.gingerall.com/] http://www.gingerall.com/. It allows you to
use pages designed for Apache mod_xslt in Caudium without modifications.
Also the output of these generated pages can also be parsed by our RXML
parser before sending the result to the client.
-----------------------------------------------------------------------------
2.2. Caudium vs Roxen: Why a fork?
Caudium is backward compatible with Roxen Challenger 1.3. It has all the
Roxen 1.3 RXML tags and the Roxen 1.3 API, so, from a technical point of
view, it is quite the same (although Caudium has many improvements over Roxen
1.3). The main legal difference between Roxen 1.3 and Caudium is that Roxen
is property of Roxen Internet Software whereas Caudium is owned by its
developers, The Caudium Group. There are many functional extensions,
improvements and bug fixes over the original Roxen 1.3 code base from which
Caudium was created. Here you may say it is not a problem since it is under
GPL. The problem is that even it is licensed under the GPL, RIS may not
include your patch in its CVS tree, you may not have a CVS account, so you
can't really do all you want. The main reason for the fork, however, was that
RIS didn't pay attention to the users' needs, and proceeded to make the new
versions of the Roxen Web Server largely incompatible with the previous
versions, to the point where one couldn't switch to the new version of the
software without much effort put into conversion of the old source code.
Rewriting huge portions of RXML/Pike code just to switch to a new version of
the web server seemed to be quite counter-productive, and thus the Caudium
Project was born.
-----------------------------------------------------------------------------
2.3. Comparing Caudium with Apache
Caudium differs from Apache in many ways including the directory structure,
programming language, and type of configuration. Caudium has a fully
integrated web interface, while Apache relies on editing text files directly.
Moreover, any change to the Apache configuration requires a restart of the
server, while Caudium sees the changes immediately after you save them from
the web interface. There are also some differences in the vocabulary used in
the configuration interface. Another difference is that Apache 1.3 uses a
forked process model while Caudium uses threads or a monolithic process
model, depending on the features present in the copy of Pike it uses. Caudium
allows the programmer/user to easily extend the server using modules/scripts
written in Pike that integrate tightly with the core server and, thus, create
a more robust, faster and more intuitive entity than an Apache server
augmented with a set of external dynamically loadable libraries. While
changing anything in the source code of any Apache extension (or the server
itself) requires recompilation, relinking and restarting of the whole server,
Caudium allows one to add/remove/modify code without any interruption of the
server operation. If you modify a module all you need to do to see the
effects of your work is to reload the module in question using the
configuration interface. Caudium's architecture also provides easy means of
building highly dynamic web pages that use SQL, gdbm, Mird databases, LDAP,
dynamically generated graphics (including business graphics modules) and
more. The same effect can be achieved with Apache almost only by using
external set of Perl, Python, or other language, scripts running as CGI or
embedded using a dynamically loaded module. While allowing the programmer/
designer to use CGI modules, Caudium offers more power when the source code
is integrated with the Caudium core.
-----------------------------------------------------------------------------
2.4. Advantages of Caudium
  *  Stable multi-threaded programming (Roxen has been multi-threaded since
1994).
  *  Mostly written in an interpreted, object-oriented, language - Pike:
  +  Easy to program and extend. Just imagine if you could code
extensions to the Apache core in PHP or Perl.
  +  No buffer overflows, segmentation faults or any other problems of
that nature.
  +  RealNetworks is still using Roxen 1.3 as their main web platform
for its stability and speed.
  *  Low level API available for end-users.
  *  RXML tags.
  *  Lots of modules.
  *  Backwards compatible with Roxen 1.3.
  *  Different. If you are a Linux or BSD user for some time you already
know the most used is not always the best.
  *  Caudium won't run under win32 (thus letting us more time for useful
things). However some people are trying to port it using cygwin without
code modification.
  *  Embedded PHP4 support.
-----------------------------------------------------------------------------
2.5. Disadvantages of Caudium
  *  Too small of a community, and quite unknown in web server world. One
example of the problem you may have is if you write Pike code for
Caudium, and your hosting company doesn't support Pike, and you don't
have root access to your server. Of course, it is possible to compile
Pike on your account and run Caudium without the superuser privileges.
  *  RIS (Roxen Internet Software) owns Pike, but this is likely to change
in the not-so-distant future.
  *  Needs more testing for exotic modules or modules we don't use often.
Example of such modules include htaccess support.
  *  Too little documentation. One example is the lack of documentation
about FastCGI support.
  *  CGI performance on busy CGI based sites was lackluster -- no one will
take the time to rewrite CGIs. This seems to be somewhat resolved with
Pike 7.2/Caudium 1.2.
  *  It is sometimes impossible to get some features when you are a normal
user because configuration is only accessible with the CIF.
(Configuration InterFace). And the CIF. is accessible only by the admin
(this is being taken care of in the development series of the server).
Here is list of day to day problems submitted by Chris Davies:
Webmasters like to use mod_rewrite in the .htaccess files to
protect their sites from leeching, etc. Yes, there is referrerdeny
and browserdeny, but these are accessible to the System
Administrator, not the casual web user. On Apache, one can easily
specify rules on a per directory basis. This isn't easy in Caudium,
however, it is rare that someone would have more than two or three
different conditions.
Now, for people that are running their own server, many of these
issues disappear. Administration and adding servers is much easier.
I'm not sure I agree with the templates, but perhaps an Apache
Template could be tweaking beyond that to the System Administrator.
In most cases, Apache has SSI turned on for shtml files -- getting
the exec command enabled to mimic this in Caudium is not a task for
the beginner. The maze of options to find that one setting will
certainly frustrate anyone getting started.
  *  A graphical interface is not always the best. To create a virtual
server with Apache, you have to copy and paste five lines. If you use the
Caudium Interface it will take you more than one minute. And if you want
to change Caudium text file directly, you will have to write sed script.
-----------------------------------------------------------------------------
Chapter 3. Getting packages
3.1. How to get packages for Debian GNU/Linux
In Debian GNU/Linux Woody, also known as Debian 3.0, Caudium and Pike 7.0
and 7.2 are included in the distribution. If you use Woody, you will have
Caudium 1.0 and Pike 7.0/7.2. If you use Sid you will have the latest Caudium
and the latest Pike; these two packages are actively maintained by the
Caudium community, and you will have frequent updates. If you want to test
the latest Caudium under Woody, add this to your /etc/apt/sources.list:
deb http://grendel.firewall.com/debian/caudium/1.2 unstable main
This location is mirrored in other locations, so you can also use:
deb http://ftp.oav.net/caudium unstable main
deb ftp://ftp.oav.net/caudium unstable main
If you want php4 Debian package for Caudium, you can do:
# su -
# apt-get update
# apt-get install -f caudium caudium-modules \
caudium-ultralog caudium-pixsl caudium-dev
And then grab the PHP4 sources:
# exit
$ cd /usr/src; apt-get source -d php4; apt-get build-dep php4
If you don't have devscripts and debhelper installed, install them now. Then
enter the /usr/src/php-4* directory and do:
$ debuild binary
After some time and some coffee you should have php4 packages for Apache, CGI
and your fresh Caudium.
-----------------------------------------------------------------------------
3.2. How to get packages for FreeBSD
Caudium 1.0 and Pike 7.0 are in the official FreeBSD ports. There are also
available as a binary package in the FreeBSD 4.7 CDROMs.
Note Caudium 1.2 and Pike 7.2 are available as ports tarballs at [ftp://
ftp.oav.net/pkg_freebsd/ports.tar.gz] ftp://ftp.oav.net/pkg_freebsd/
ports.tar.gz. If you take the latest ports from this site use the
following command:
$ cd /tmp
$ fetch ftp://ftp.oav.net/pkg_freebsd/ports.tar.gz
Receiving ports.tar.gz (32468 bytes): 100%
32468 bytes transferred in 0.6 seconds (53.87 kBps)
$ su -
# cd /usr/
# tar xzf /tmp/ports.tar.gz
Another note, since Caudium and Pike have been added recently to FreeBSD
port tree, you must have an up to date port tree. See the FreeBSD
handbook at [http://www.freebsd.org/handbook/cvsup.html] http://
www.freebsd.org/handbook/cvsup.html about cvsup handling.
As root, go to /usr/ports/www/caudium10 to install current stable version,
/usr/ports/www/caudium12 to install the next stable version in Release
Candidate process, or /usr/ports/www/caudium-dev to install the current
developer's version. The script will automatically fetch and install Pike,
try to detect what library you've installed and compile all the necessary
libs for Caudium and Pike.
Here is the current Pike / Caudium options supported by the current port :
  *  WITH_MOST : Install the FreeType1 and FreeType2 support.
  *  WITH_OPTIMIZED_CFLAGS : Add some performance flags to the compiler.
  *  WITH_TTF : Install the FreeType1 support.
  *  WITH_FREETYPE : Install the FreeType2 support.
  *  WITH_MYSQL : Install the MySQL support.
  *  WITH_POSTGRES : Install the PostgreSQL support.
  *  WITH_MSQL : Install mSQL support.
  *  WITH_UNIXODBC : Install UnixODBC support (incompatible option with
WITH_IODBC).
  *  WITH_IODBC : Install iODBC support (incompatible option with
WITH_UNIXODBC).
  *  WITH_SANE : Install SANE backend.
  *  WITH_PDF : Install PDF support
  *  WITH_MESA/HAVE_MESA : Install MesaGL support.
  *  HAVE_GNOME/WANT_GNOME : Install GNOME support.
There are some options related only to Pike, like the GNOME / Mesa ones that
are uninteresting to Caudium, but exist for Pike support.
A little example on how to install Caudium on FreeBSD :
# cd /usr/ports/www/caudium12
# make WITH_MOST=yes WITH_MYSQL=yes WITH_OPTIMIZED_CFLAGS=yes install clean
===> Extracting for caudium-1.2.6
>> Checksum OK for caudium-1.2.6.tar.gz.
===> caudium-1.2.6 depends on executable: pike - found
===> caudium-1.2.6 depends on executable: gmake - found
===> caudium-1.2.6 depends on shared library: sablot.67 - found
[...]
===> Generating temporary packing list
***************************************************************
If this is the first installation of Caudium, please go the
caudium's directory and execute the server/install script
to finish the Caudium installation.
If your are upgrading, just start caudium as usual.
NOTE: there is an automatic starting script in etc/rc.d/
***************************************************************
===> Registering installation for caudium-1.2.6
===> SECURITY NOTE:
This port has installed the following startup scripts which may cause
network services to be started at boot time.
/usr/local/etc/rc.d/caudium.sh.sample
If there are vulnerabilities in these programs there may be a security
risk to the system. FreeBSD makes no guarantee about the security of
ports included in the Ports Collection. Please type 'make deinstall'
to deinstall the port if this is a concern.
For more information, and contact details about the security
status of this software, see the following webpage:
http://caudium.net/
===> Cleaning for libiconv-1.7_5
===> Cleaning for gdbm-1.8.0
===> Cleaning for mird-1.0.7
===> Cleaning for mysql-client-3.23.49
===> Cleaning for autoconf-2.53
===> Cleaning for autoconf213-2.13.000227_1
===> Cleaning for automake14-1.4.5
===> Cleaning for bison-1.35_1
===> Cleaning for gettext-0.11.1_3
===> Cleaning for gmake-3.79.1_1
===> Cleaning for libtool-1.3.4_3
===> Cleaning for m4-1.4_1
===> Cleaning for nasm-0.98,1
===> Cleaning for jpeg-6b_1
===> Cleaning for tiff-3.5.7
===> Cleaning for pexts-20020121
===> Cleaning for pike72cvs-7.2.356_5
===> Cleaning for libgmp-4.0.1
===> Cleaning for freetype-1.3.1_2
===> Cleaning for freetype2-2.0.9
===> Cleaning for libmcrypt-2.5.0
===> Cleaning for mhash-0.8.14
===> Cleaning for expat-1.95.2
===> Cleaning for Sablot-0.81_1
===> Cleaning for caudium-1.2.6
#
Now if you need to install PHP4 support for Caudium, just go to /usr/ports/
www/caudium_php4 and do a make install clean as well.
-----------------------------------------------------------------------------
3.3. How to get packages for Solaris
Bill Welliver has made some packages. They are available on [http://
hww3.riverweb.com/dist/] Riverweb and mirrored to [ftp://ftp.oav.net/caudium/
pkg/solaris/] Oav.net.
-----------------------------------------------------------------------------
3.4. How to get CAMAS from CVS/source
To get CAMAS from the CVS, go to the [http://camas.caudium.net/] CAMAS web
site and follow the link.
-----------------------------------------------------------------------------
Chapter 4. Creating your first server
4.1. Installing Caudium from sources
You need to install Pike before you can install Caudium. The version of
Pike is different depending on the Caudium version you want to install. For
Caudium 1.0, use Pike 7.0; for Caudium 1.2, use Pike 7.2. You can find some
Pike packages for the most popular systems: Debian GNU/Linux (Woody/Sid),
FreeBSD, Solaris.
Note To take a CVS source snapshot of Pike 7.2+, you will need to have a
preinstalled Pike (any version) on your system in order to compile the
fresh CVS checkout. This is because the CVS sources need to pre-process
certain parts of the sources with some special Pike scripts. Downloading
a tarball from the RIS site (always outdated) will free you from the
requirement of having the Pike installed before compiling the CVS
snapshot.
For more information, see the quick start guide at [http://caudium.net/]
http://caudium.net/.
-----------------------------------------------------------------------------
4.2. Starting
The first time you install Caudium from the sources, you will need to type
the following commands:
# su -
# cd /usr/local/caudium
# ./install
This script will allow you to give login information for the Configuration
InterFace (CIF.), the web based configuration interface, and the port address
for the CIF.. But if you want to start Caudium manually, you don't need to
use install, just use the start script. This script will fork Caudium once
and restart it automatically if it dies. A consequence is that if you kill
start, the server will always be running but it will not restart if it dies.
There are many useful options to start. The first is --help. Here is a
non-exhaustive list of options:
  *  --once: Do not fork Caudium and output debug to stdout (screen). If you
hit CTRL-C, Caudium will be killed
  *  -t: Display all Pike calls
  *  --gdb: Run Caudium inside gdb, useful only for developers.
  *  --with-threads: Run Caudium with threads (run better on *BSD and
Solaris)
  *  --without-threads: The opposite of --with-threads. It doesn't mean that
the Pike scripts/modules aren't able to use threads. It merely means that
the Caudium core server will not use threaded handler backend.
  *  --with-keep-alive: Enable keep-alive in HTTP. In the old days of the
web, the HTTP protocol was simple but not efficient: one connection was
made for each objects requested by a client. That means a web browser
made 20 connections to the webserver if there was 19 images on a webpage
and the HTML page itself. This result in a lot of overhead and response
time delay. With keep alive, the server don't close the connection for
each objects so the browser can request several objects with one HTTP
connection and does not need to reconnect each time. As a result, the
website seems to be faster for the client and the webserver can handle
more users.
Note Currently, the keep-alive option doesn't work with CAMAS (I use
CAMAS-1.1.7-DEV, Caudium 1.2RC1). Generally speaking, it is also not
ready for production use. Here is a comment from Xavier Beaudouin:
keep-alive is somewhat buggy on Caudium. My test shows that high
number of connections on keep-alived Caudium show some random
dropped returns. I do not recommend using keep-alive. If you'd
like keep-alive a "black box" like redline seems the best
solution... but expensive.
  *  --config-dir=DIR: Allows you to specify where your configuration files
are, where "DIR" is the name of the directory holding the configuration
files (typically /usr/local/caudium/configurations/). This is a very
useful option. For example you can start several Caudium instances with
different configurations by using different configuration directories.
This is also useful if you put the configuration files in a non-standard
directory: /usr/local/caudium/server/start --config-dir=/home/david/etc/
my_caudium_configuration/ For Apache users, this is the equivalent of the
-f option but points to the directory that contains the files.
Finally, the most important thing is debug log files. These files are
stored in ../logs/debug (relative to /usr/local/caudium/server in our
example). The current log file is named default.1. The log file from the last
Caudium start is default.2 and so on. If you didn't enable debug, these files
are always used but contain very few messages.
Note The location of files may be different on your system if you are using a
prepackaged version of the software.
-----------------------------------------------------------------------------
4.3. Stopping from command line
There are two ways to stop Caudium:
  *  Kill Caudium with a -9 signal. If you do this Caudium will restart.
Actually it will be restarted by the start script.
  *  Kill Caudium (with kill(1)'s default TERM signal) . In this case,
Caudium will stop cleanly. If you use Caudium 1.2 and later, you can use
the caudiumctl command. A man page for caudiumctl should be available on
your system.
Note In both cases Caudium will stop only after a few moments.
On Debian GNU/Linux, you can use the following commands to manipulate the
server status:
# /etc/init.d/caudium stop
# /etc/init.d/caudium start
# /etc/init.d/caudium restart
-----------------------------------------------------------------------------
4.4. Directory organization
  *  configurations:
Contains the config files used by the CIF.. These files use the XML
syntax. You don't have to modify them by hand. If for some reason you do,
make sure to do it when Caudium is stopped because they will get
overwritten with the server's current configuration when the server is
stopped. An alternate method is to edit the file, then send the HUP
signal to the Caudium process. Another method is to use the CIF.: Go into
Action -> Maintenance -> Reload configurations from disk. This will cause
Caudium to reload its configuration from disk. As you may have guessed,
each file has the name of the corresponding virtual server. One file
however has a special name - Global_Variables. This file contains
information about Caudium's global variables (See the Global Variables
tab in the CIF.).
  *  logs:
Contains useful information such as debug log, virtual server logs,
start/stop status. See also Section 4.2.
  *  readme:
It's all in the name.
  *  server:
This directory contains the actual server.
  +  base_server:
Contains the server core Pike code: API, CIF., etc. Newbies should
not modify these files.
  +  bin:
First binary code that is run when you use the start script. There
are also some Pike scripts running as CGIs and without Caudium API.
  +  caudium-images:
This directory contains Caudium static images from the Caudium
Group, such as the "powered by" series.
  +  config_actions:
These are files used in the Action tab on the CIF.. You may use
some of these functions in your code.
  +  etc:
Caudium includes files used by the Caudium core and its modules.
For example, it contains .html files for error messages. Two
directories are important for a module developer:
  o  include:
Put your .h files here.
  o  module:
Put your module files here (.pmod). Pike module files are used
to provide two-level functions/class/methods for your modules.
When you modify any of these files, you must restart the server.
  +  fonts:
Contains some compatibility fonts with some older versions. The new
directory is nfonts.
  +  languages:
Some basic language translations for time/date.
  +  lib:
Some of the C code used to speed Caudium up. This code is a set of
dynamic libraries (.so).
  +  modules:
Contains Caudium modules. These are all the modules you see when
you click Add Module after you have selected one of your servers in
the CIF.. Browsing this directory will be useful to understand
Caudium.
  o  3rdparty:
This special directory contains third party modules for
Caudium. These may be useful but are provided without any
warranty and will not be maintained by the Caudium Group but they
may be by the individuals who wrote them.
  +  more_modules:
Some modules that meet a specific need, are not up-to-date, or are
humorous.
  +  nfonts:
Fonts for graphical things like <gtext> and <gbutton>. You can have
several types of properties like bold or italic for the same font
name.
  +  Perl:
Needed to run Perl scripts within Caudium. At the time of writing
this document, Perl support is broken, and we will be pleased to get
help on this issue.
  +  protocols:
Contains protocol modules (for handling HTTP, FTP and the like).
  +  server_templates:
The templates you can choose from when you create a new a virtual
server.
  +  unfinished_modules:
For modules in development.
You can also see readme/README relative to /usr/local/caudium in our
example.
-----------------------------------------------------------------------------
4.5. Upgrading Caudium
Upgrading Caudium is simple. You should install it as if for the first
time. That is, get the new sources, unpack them, run ./configure; make; make
install and that's all. The new Caudium installation will detect your old
Caudium and keep all your old installation including your config files. The
config files will be compatible with the new version so you will never have
to begin the configuration task a second time. The old server directory will
be saved as server.old and so the new one will be put in the classical server
directory.
If you use a package system, just use the upgrading features of your
packaging system.
-----------------------------------------------------------------------------
4.6. Configuration InterFace (CIF.)
The CIF. is where the administrator manages the server. When you first
login it looks like this.
[cif_1stpage]
The first page you will see when you login on the CIF.
In the CIF, you'll find four tabs:
1. [virtual_servers]
The server(s) you have created in this Caudium installation. This is
where you will tune each server configuration.
2. [global_variables]
The configuration variables that affect Caudium as a whole, including
all virtual servers.
3. [event_log]
The log file output as a nice looking log. Note however, that neither
errors nor startup events are displayed in the event log. This means
developers should always look in the plain log file.
4. [actions]
Some actions you may take on you servers such as shutting down Caudium
or generating an SSL certificate. This allows you to avoid some of the
command line stuff.
As the CIF. is quite easy to cope with, I will try to describe some of the
hidden things you may need to know about. One of them is the [more_options]
button. This button is very useful. Furthermore, some Basic options will not
be available unless you turn it on. With this option, you will have more
control over Global Variables and some modules in Virtual Servers.
One of these controls is the [reload_module] button that you will have
when you are in a module. This button will allow developers to check the new
code of their modules without restarting Caudium. You should also know that
very few options in some modules will not be activated unless you reload the
module. So always reload a module when you think an option has not been read
by Caudium.
-----------------------------------------------------------------------------
4.7. Adding your first server
In this section, I will give you a step-by-step tutorial on how to create
your first site (virtual server) with Caudium. If you want to do something
useful with Caudium, you have to create at least one virtual server. Without
this first server, Caudium will not do anything. If you use your browser to
access your server, you will only get a dialog box prompting for the CIF.
login/password.
Note A virtual server allows you to have several servers running on the same
port. For example you can have www.foo.com and www.foo.org running on
the same port and machine. This is why it is called virtual server.
To create your first server, log into the web based CIF.. Click on the
Virtual Servers tab, then the [new_virtual_server] button.
Here, you are prompted for the server name:
[cif_newserver]
Type in an easily identifiable name. You also have to select the
configuration type. Depending on the configuration you choose, your server
will have a different set of modules. In other words, your server will have
different capabilities. For your first server, choose Basic server, and click
OK.
-----------------------------------------------------------------------------
4.7.1. Server variables
Now you'll see the Virtual Servers page again. As you can see, you have two
different folders to work on: Server variables (Figure 4-1) and File system (
Figure 4-2).
Figure 4-1. Ports in the CIF
[cif_ports]
Figure 4-2. Filesystem in the CIF
[cif_filesystem]
Server variables contain the URL of your site, and the port on which it will
be available. File system describes the files/directories containing the
.html and other files you want Caudium to serve.
In server variables, go into Listen ports and choose Configure a new port.
Use the default values, choose Use these values, and click [save] . Now
select the URL of your site, and select Continue. You can now go back to the
page displaying all of your modules, that is, where you were before you had
gone into Server Variables.
Under your server name, you'll see the status of your server. If it
contains the word "Open" in blue everything is okay, and you can continue
with configuring the file system.
If it contains the words "Not open" in red, there is a problem. You can go
into the Event Log via the CIF. tab to investigate. If you have an error
[err_3] Failed to open socket on 0:80 (already bound ?), you may have another
program or Caudium itself already running on this port. To fix the problem,
identify the program which is using this port, and restart Caudium [1]. To
restart Caudium, go into Action->Shutdown->Shutdown Caudium->Restart Caudium.
Wait a few seconds, and when prompted, select Virtual Servers. Now select
your server, and you should have the word "Open" in blue.
Note In the CIF. you may wonder what are those two different protocols http
and http2?
  The difference is that http2 uses Caudium's internal memory cache while
http is plain Pike http subsystem. So http2 is faster than http as you
might expect. However, there are some issues on some specific sites.
-----------------------------------------------------------------------------
4.7.2. Selecting file system
By selecting a file system, you tell Caudium which files it will send to
people browsing your site. For those who know other web servers, please pay
close attention to these explanations, because Caudium is quite different
from other servers in this respect.
Caudium file systems use the Unix philosophy of mount point, rather than
c:, d:, and so forth. The mount point concept allows you to put your files/
directory under any URL you want without changing the files on your local
file system. For example, assume you have the following local file system:
Example 4-1. Your user filesystem.
/home/customers/customer1
/home/customers/customer2
/home/customers/bigcustomer3
/home/friends/franck
/home/friends/bertrand
/home/friends/didier
And suppose your URL is http://www.iteam.org/.
With a default configuration, you would say that http://www.iteam.org
points to /home/ so that you will have customer1 under http://www.iteam.org/
customers/customer1, bertrand under http://www.iteam.org/friends/bertrand and
bigcustomer3 under http://www.iteam.org/customers/bigcustomer3.
But bigcustomer3 gives you a lot of money and he asks you for an URL such
as http://www.iteam.org/bigcustomer3. However, he doesn't want to be moved
from /home/customers/bigcustomer3 because of his FTP client's configuration.
Moreover, you can't move the other accounts. With the mount point philosophy,
you just have to create another mount point saying that /home/customers/
bigcustomer3 is mounted on /bigcustomer3 so that when someone uses http://
www.iteam.org/bigcustomer3, Caudium will serve them files from /home/
customers/bigcustomer3.
Now let's return to our setup. Go into the File System module, and select
NONE/ mounted on / -> Path -> Search Path. Here you will decide which of your
directories will be available when someone hits the root of your server.
Write, for example, /home.
You can now launch your favorite browser to the URL of your site and enjoy.
If you don't want visitors to get a listing of your files for security
reasons, you can disable listing by setting Directory Settings -> Enable
directory listing per default to No. Next you have to hit the More options
button, and then reload the module. Don't forget to click Save. It is
possible to put one of two "magic files" in any directory to make it
browsable/not browsable despite the setting in the CIF. for that particular
file system:
.www_browsable - the directory will always be browsable
.www_not_browsable - the directory will never be browsable
Finally, to allow bigcustomer3 to get to his URL, go to File System -> Copy
Module. Next, go to Path -> Search Path and type /home/customers/bigcustomer3
, then type /bigcustomer3 in Mount point.
The Figure 4-3 shows the output you should have.
Figure 4-3. Example of output
[cif_filesystem_example]
Note If you created these files/directories after you point Caudium to your
site, it is safe to go in the Actions tab, then to Cache -> Cache status
-> Flush caches.
-----------------------------------------------------------------------------
4.7.3. Creating a virtual server
A web server is usually running on a single port and on a single IP
address. So how can someone have different sites on this single port and
single IP? The solution is to tell Caudium that the server is different based
on the URL. This is the task of the Virtual Hosting module. As this module is
not present in the Generic template we use, you will have to add it. Just use
the Add module button, and click the image named "Virtual Host Matcher".
You are now able to do redirection with the help of regular expressions. If
you don't know what regular expressions ("regexp" for short) are, check the
man page for regexp, see Pike/Perl manual, or maybe buy a book on regular
expressions. To write these redirections based on the URL, go into Regular
expression rewrite rules and add the following rule:
Example 4-2. A simple virtual hosting regular expression.
www\.virtualhost\.com www.virtualhost.com
Example 4-3. A better and quicker regular expression.
^www\.virtualhost\.com$|^virtualhost\.com$ www.virtualhost.com
Save and type this command on your command line in order to get your
browser resolving www.virtualhost.com:
# echo "127.0.0.1 www.virtualhost.com" >> /etc/hosts.
You now have to add another virtual server with the button New Virtual
Server at the root of the virtual server tab. Put Virtual host as the server
name and choose the Generic server configuration type. Go into Server
variables -> Server URL and type http://www.virtualhost.com/. You should see:
This server is handled by the port in my first virtual server. Server URL:
http://www.virtualhost.com/
Change the file system root and /tmp in File system -> NONE/ mounted on / -
> Paths -> Search path.
You can now point your favorite browser to http://localhost/ and http://
www.virtualhost.com/ and see the result.
If you have an error telling you www.virtualhost.com is unknown check your
host file.
For more information about virtual hosting, see the Virtual-Web Mini-HOWTO
available at the [http://www.tldp.org/] LDP or in /usr/share/doc/HOWTO or /
usr/doc/HOWTO under Debian GNU/Linux.
-----------------------------------------------------------------------------
Chapter 5. Customizing your server
5.1. How to run Caudium as a non-privileged user; How to secure Caudium
Web servers are usually publicly accessible and represent your company,
group or entity so there are chances you want to strengthen the security of
this service.
As I already mentioned Caudium has a good security for public access behind
mostly written in a script language. However Caudium runs as root by default.
In the case a non-authorized user gains access to Caudium's process, he might
gain root privileges. Consequently,a lot of web servers run as another user
with minimal privileges. Doing this may require some work, as you will have
to change the owner of all the files Caudium needs access to, so I give
step-by-step instructions how to change those permissions:
1. Find a good user name. This user name should be a normal user with the
least privileges. Lots of distributions already have a special account
for this. Common names include "www", "www-data", "httpd", "nobody"
(Caudium on Debian GNU/Linux runs as www-data:www-data by default). We
don't recommend "nobody" though; to quote Theo de Raadt:
The user "nobody" has historically been doing too much. If you could
break into the user "nobody", you could cause great damage.
2. Change the owner of the files which Caudium needs to write to. These
include:
  +  Caudium internal log file (default.*).
  +  Per virtual server log file.
  +  All caches.
  +  The configurations files (they are written by the CIF.).
On a Caudium source install the following command should do the job:
# chown -R www-data.www-data logs/ var/
argument_cache/ bgcache/ configurations/ server/*.pem server
Here is the result:
$ ls -l
total 32
drwxr-sr-x 6 www-data www-data 4096 Feb 13 23:17 argument_cache
drwxr-sr-x 2 www-data www-data 4096 Feb 19 09:27 bgcache
drwxr-sr-x 2 www-data www-data 4096 Mar 4 22:28 configurations
drwxr-sr-x 4 root staff 4096 Feb 13 23:16 local
drwxr-sr-x 7 www-data www-data 4096 Mar 3 11:50 logs
drwxr-sr-x 2 root staff 4096 Feb 13 23:16 readme
drwxr-sr-x 19 www-data www-data 4096 Feb 19 20:13 server
drwxr-sr-x 2 www-data www-data 4096 Mar 3 19:28 var
$ id www-data
uid=33(www-data) gid=33(www-data) groups=33(www-data)
If users are allowed to log on the server, you might also change the
permissions of the logs directory.
If you have a Caudium specific distribution for your system (such as
Debian GNU/Linux) check manually.
3. Don't forget to change the permissions of any script/directory you made
and for which Caudium needs to write to in your public filesystem.
4. Log into the CIF., go in the main Global variables tab, then in Change
uid and gid type the uid:gid data you choose. We typed 33:33 in our
example. You can also type a login name and group name: www-data:www-data
. You can also enable the Change uid and gid permanently option but be
sure to read the documentation first.
I will now speak about general security measures you can take if you are
very strict about security.
1. Don't allow users to execute scripts that are part of the server.
As Caudium is a single process server, it is possible to stop it,
restart it, access it, etc. with a user script. This include pike
scripts, pike tag, and PHP modules for Caudium.
If you do want to let your users run scripts, you can always use CGI,
or better uniscript (in this case it will be transparent to the user), in
order to run a script in a separate process using the fork(2) system
call. This will decrease the performance of Caudium but the security has
a price, and it is up to you to decide how much you want to pay.
Note Uniscript is a CGI-like wrapper. It will execute programs as if they
were CGI scripts but unlike CGI, it does not require you to put
these programs under a specific directory like /cgi-bin/. For
example each user can have his or her CGI script in his or her
directory. Moreover Caudium can execute them with the uid of the
owner.
2. Don't use anything you don't need. Remove any modules you don't need in
your virtual server.
3. Physically restrict access to the CIF.. Don't access it from the
Internet if possible. Few people know this, but it is now possible to see
SSL connections in clear text with a man-in-the-middle attack. The dsniff
software contains all the tools and explanation for this.
4. Turn off these options:
  +  Global Variables -> show_internals.
  +  Global Variables -> Version numbers -> Show Caudium Version Number.
  +  Global Variables -> Version numbers -> Show Pike Version Number.
Turn off any debug options specific to a module. These options are for
developers, and they don't have security in mind when they debug output.
  Actually, this is security through obscurity and doesn't  
increase the security of the server.
--Grendel  
5. Output Caudium's log files to a separate partition. /var is a good
choice for that purpose.
6. Check the Caudium web site for patches.
7. If your job relies on your web server security, check the Caudium
source.
-----------------------------------------------------------------------------
5.2. How to benchmark a web server
First, benchmarking a web server is not an easy thing. To benchmark a web
server the time it will take to give a page is not important: you don't care
if a user can have his page in 0.1 ms or in 0.05 ms as nobody can have such
delays on the Internet.
What is important is the average time it will take when you have a maximum
number of users on your site simultaneously. Another important thing is how
much more time it will take when there are 2 times more users: a server that
take 2 times more for 2 times more users is better than another that take 4
times more for the same amount of users. If you run more than a web server on
your computer, you will also want to look at the load average and CPU time of
your system. Here is a typical output of the command uptime:
22:39:49 up 2:22, 5 users, load average: 0.01, 0.01, 0.00
And an extract from the top(1) man page:
" The load averages are the average number of process ready to run during
the last 1, 5 and 15 minutes "
So the lower your load average is, the better for the other programs on
your machine.
Now comes the next problem: how can you stress your web server with a
maximum number of connections when your client (the machine making the
request) will usually not be able to cope with the server and with the number
of users you have.
To do this, increase the number of sockets you can have on your system.
Under some systems it is 1024, which is too low, see Section 5.3 for more
information. The next thing to do is to have a good client program written
with threads and non-blocking sockets. If you use a multi-fork program on a
single client, it will never cope with any web server. It is also good to
have several clients stressing the server together.
Last, if you want to compare two web servers, be sure that they are on the
same hardware, OS, and network. The same holds for the client(s).
-----------------------------------------------------------------------------
5.3. How to tune your system for best Caudium performances
5.3.1. Linux
Until a Linux guru has time to make some nice documentation, here is
something that came from PureFtpd software :
o Increase your system max descriptors numbers :
# echo 60000 > /proc/sys/fs/file-max
# echo 180000 > /proc/sys/fs/inode-max
# ulimit -n 60000
o mount your filesystems with the "noatime" option
o make sure your disks holding the logs are "fast enough"
o You can tweak a bit your TCP/IP stack :
# echo 0 > /proc/sys/net/ipv4/tcp_syncookies
# echo 0 > /proc/sys/net/ipv4/tcp_ecn
# echo 0 > /proc/sys/net/ipv4/tcp_timestamps
# echo 0 > /proc/sys/net/ipv4/tcp_window_scaling
Finally don't forget to compile Pike with --with-max-fd=60000 (already done
in Debian packages).
Warning Warning from Caudium people
    * Personally deactivate window scaling seems to be a bad idea.
  * This needs some touches. 2.2 and 2.4 options are mixed above very
badly. Also, turning off ECN might do you more harm than gain.
Also see [http://linuxperf.nl.linux.org/] LinuxPerf, and [http://
linuxperf.nl.linux.org/general/kerneltuning.html] LinuxPerf kernel tuning
section.
-----------------------------------------------------------------------------
5.3.2. FreeBSD
Here are the optimizations you can try on your servers. They are provided
without any warranty.
Note All this is for FreeBSD 4.2 or more recent.
First, check to see if your filesystems use Soft Updates:
# tunefs -p /dev/da0s1a
tunefs: soft updates: (-n) disabled
tunefs: maximum contiguous block count: (-a) 15
tunefs: rotational delay between contiguous blocks: (-d) 0 ms
tunefs: maximum blocks per file in a cylinder group: (-e) 2048
tunefs: average file size: (-f) 16384
tunefs: average number of files in a directory: (-s) 64
tunefs: minimum percentage of free space: (-m) 8%
tunefs: optimization preference: (-o) time
If soft updates are set to disabled it may be a good idea to enable them. We
do not recommend you enable them on "/" filesystem on servers machines, there
are issues and in general this is not recommended by the FreeBSD team. If you
can unmount the others filesystems do this and remount them later:
# tunefs -n enable /dev/"whatever"
If you cannot unmount the others filesystem, drop into single mode (do a
shutdown now or a boot -s) and then type:
# tunefs -n enable "filesystem"
I suggest /usr or /var. In the fstab you can add ,async to the options of all
filesystems. As for soft updates we do not recommend that on server machines
for the root (/) filesystem.
In /boot/loader.conf add the following:
kern.ipc.maxsockets="5000"
kern.ipc.nmbclusters="65536"
If you have ATA (IDE / UltraDMA) disks you can add also in /boot/loader.conf:
hw.ata.wc="1"
Then in /etc/sysctl.conf you can add:
vfs.vmiodirenable=1
kern.ipc.maxsockbuf=2097152
kern.ipc.somaxconn=8192
kern.ipc.maxsockets=16424
kern.maxfiles=65536
kern.maxfilesperproc=32768
net.inet.tcp.rfc1323=1
net.inet.tcp.delayed_ack=0
net.inet.tcp.sendspace=65535
net.inet.tcp.recvspace=65535
net.inet.udp.recvspace=65535
net.inet.udp.maxdgram=57344
net.local.stream.recvspace=65535
net.local.stream.sendspace=65535
And then reboot (or for /etc/sysctl.conf use the sysctl(8) tool to setup this
by hand.
Another way to have good performance is to make a custom kernel, with the
minimum of drivers and processor support. A maxuser size = size of memory
(for example you have 512M of RAM, then set the maxusers value in your kernel
configuration variable to 512). Add Posix 1003.1b real time extensions to the
kernel with:
options P1003_1B #Posix P1003_1B real-time extensions
options _KPOSIX_PRIORITY_SCHEDULING
Enable the SMP options (only for FreeBSD 4.x, the FreeBSD 5.0 is now
automatic).
For French users, check these URLs :
  *  [http://gcu-squad.org/?viewtip+&tip_id=59] http://gcu-squad.org/?
viewtip+&tip_id=59.
  *  [http://gcu-squad.org/?viewtip+&tip_id=54] http://gcu-squad.org/?
viewtip+&tip_id=54.
-----------------------------------------------------------------------------
5.3.3. Solaris 2.x
Most of the optimization values are in /etc/system file. This file is read
by the kernel when it is loading. Please notice that the following
optimization is focused on Solaris 8 machines with at least 256M of RAM.
* A comment is started by a star '*'
*
* 1 maxusers per mega of ram. This machine has 512M then maxusers = 512
set maxusers=512
set hires_tick=1
set rlim_fd_max=10000
set rlim_fd_cur=4096
*set tcp:tcp_conn_hash_size=8192
* Don't setup this if you don't have more than 256M of RAM
set bufhwm=48000
* Folling are used to delay page reaping with databases.
set fastscan = 32000
set slowscan = 200
set maxpgio = 280
set lotsfree = 1024
set desfree = 512
set minfree = 128
set autoup = 280
* Hash buffer sizes during Specweb testing
set tcp:tcp_conn_hash_size = 2097152
* Nic Interface
set hme:hme_adv_100fdx_cap=1
set hme:hme_adv_100hdx_cap=0
set hme:hme_adv_10fdx_cap=0
set hme:hme_adv_10hdx_cap=0
set hme:hme_adv_autoneg_cap=0
* To prevent buffer overflow
set noexec_user_stack=1
set noexec_user_stack_log=1
Please notice that Solaris needs fast disks. If you have IDE / UDMA disks,
double check they are recent. For example the disks in Ultra 5 / 10 machines
are snail slow, and slow down the whole machine when you make read write
operation. Please consider getting faster disks.
Also, if you use software raid (Solaris Disk Suite) you will have optimal
performance if you have more than one SCSI controller in the machine.
Another good read is the well known [http://sunsite.uakom.sk/sunworldonline
/common/cockcroft.letters.html] document from Adrian Cockroft about tuning
Solaris. Sunhelp.org has also a good [http://sunhelp.org/info-faq.ph] section
about tuning. Finally, you can read a network guide at [http://www.sean.de/
Solaris/tune.html] http://www.sean.de/Solaris/tune.html.
-----------------------------------------------------------------------------
5.4. How to use your own fonts
Use the xdumpfont program in the tool directory of Caudium's sources. This
program will convert your X fonts to Caudium fonts.
If your Pike supports TrueType Fonts, (type pike --features and check if
Image.TTF is available) you can import TTF font by copying them into /usr/
local/caudium/server/fonts/ttf.
-----------------------------------------------------------------------------
5.5. How to get UltraLog working
See the Caudium documentation project at [http://caudium.info/] http://
caudium.info/, and [http://daviesinc.com/modules/docs/ultralog.rxml] http://
daviesinc.com/modules/docs/ultralog.rxml.
-----------------------------------------------------------------------------
Chapter 6. Developing with Caudium
6.1. Your first RXML file
You can try this code. This is a basic one with only four tags/containers.
You should go to [http://caudium.info/] http://caudium.info/ and download the
Roxen 1.3 documentation.
Example 6-1. Some simple RXML tags.
<html>
<comment>You have to put bgcolor for gtext to work properly</comment>
<body bgcolor="#FFFFFF">
<h1>Basic RXML examples</h1>
<table border="1">
<tr>
<td>This is a list of all RXML tags</td>
<td><list-tags></td>
</tr>
</table>
<table border="1">
<tr>
<td>Gtext render text as graphic</td>
<td><gtext scale=0.5>This is a gif/png graphic</gtext></td>
</tr>
<tr>
<td>Last modification of this page</td>
<td><modified></td>
</tr>
</table>
</body>
</html>
-----------------------------------------------------------------------------
6.2. The Pike tag
For a complete tutorial and reference manual on Pike, see [http://
pike.oav.net/] http://pike.oav.net/.
The Pike tag allows you to easily insert Pike code into your HTML page à la
PHP. This is a good way of learning Pike if you have a PHP background or if
you want to do things very easily and don't worry about perfect results.
To do this, you have to load a module in your server. Just select Load
module in the CIF. and click the "Pike tag" image. Then hit save and create
an .html file where your public web files are. Since everybody tells me that
PHP is easy, which is why it's so popular, I took the PHP examples and
converted them to Pike. Here is the result:
Example 6-2. The PHP documentation as a Pike tag.
<html>
<body bgcolor="#FFFFFF">
<h2>Escaping from HTML</h2>
<p>
There is one way of escaping from HTML and entering "Pike code mode"
<br />
<Pike>
output("This is the simplest, and SGML processing instruction");
</Pike>
</p>
<h2>Instruction separation</h2>
<p>
Instructions are separated the same as in C or Perl:
terminate each statement with a semicolon.
The closing tag (container, in fact) also implies the end of the statement,
so the following are equivalent:
<br />
<Pike>
output ("This is a test");
</Pike>
<br />
<Pike> output ("This is a test"); </Pike>
</p>
<h2>Comments</h2>
<p>
Pike supports C, C++ but not Unix shell-style comments. For example:
<Pike>
string tests = "This is a test<br />"; // this is a one-line C++ style comment
/* This is a multi line comment
yet another line of comment */
tests += "Yet another test";
return tests;
</Pike>
</p>
<h2>Melding RXML and Pike</h2>
You will never see this in PHP.
[2]
This will create a .gif image of 1-2-...-255.
This took 0.4s on my Duron 750 the first time and 0.1s after.
<p>
<gtext scale=0.5>
<Pike>
string output = "";
for(int I = 1; I < 255; I++)
output += I + "-";
return output;
</Pike>
</gtext>
</p>
</body>
</html>
The problem with using this is that you will soon see it is not powerful:
  *  The code will become an ugly mixture of data and code even if you use
an object orientation method. The more your project grows, the less you
will be able to produce something useful.
  *  The URL will require plenty of those "&" symbols and you will have a
lot of files without real organization.
  *  The performance will not be the best.
  *  This can be considered as a security risk for servers that are opened
to unknown users (eg. public web servers).
The next step is to write your first Pike script.
-----------------------------------------------------------------------------
6.3. Your first Pike script
A Pike script is quite like a Perl script. It is executed when the user
tries to access it. So a Pike script is usually where your public web files
are. This is a good choice if you already have a Perl background and want to
try Pike.
You have two choices when doing this. You can execute Pike as a CGI script
or internally within the server. If you don't know what CGI is, look up the
Apache-Overview-HOWTO at [http://www.tldp.org/] http://www.tldp.org/.
Here, we will run Pike scripts internally within Caudium. To achieve this,
you have to load another module in your server by selecting Load module in
the CIF.. You now have the list of all modules available in Caudium. As you
see, there are a lot of modules and reading this page should give you some
ideas for future development. To select the Pike script module, just click on
the image named "Pike script support" if you use a graphical browser.
You can now create a .pike file containing, for example,
Example 6-3. A basic Pike script.
// you have to inherit caudiumlib to have some basic things
// like the id object and response mapping
inherit "caudiumlib";
// the same as the main
// if you modify this script and you see that Caudium don't take your
// modification into account, reload the Pike script support module
// This is because Caudium uses a cache for performance reasons
string parse(object id)
{
string html = "<html><body>The id object contain some "
"very useful information<br />";
html += sprintf("The id->variables contain a list of "
"arguments given to this script %O\n", id->variables);
return html;
}
Pike scripts are usually used for little internal development. Pike scripts
can be very useful in this case because you can create something with very
little lines. Here is an example of such a script:
Example 6-4. A real world script.
/* Here is a Pike script (not a Caudium module).
This script is less than 20 lines (comments
and blank lines excluded) and will randomly
return one file to the web browser from a list of files.
This script was kindly provided by Xavier Beaudouin */
// first we need to inherit from caudiumlib in order to get
// the parse, http_redirect functions and id object
// recognized.
inherit "caudiumlib";
// we declare an array of files
array (string)files;
// an ASCII text containing the name of a file
// on the real filesystem.
// Each file name in this file will be
// randomly return (the files name have to be on
// a separate line).
#define FILELIST "/list"
#define BASEDIR "/thepath2yourfiles/"
// this function is the constructor, it will be loaded first
void create () {
// the array of strings 'files' will contain
// all the files we serve provided the file
// FILELIST list each file name on one line.
files = Stdio.read_bytes(FILELIST)/"\n";
}
// if no_reload return 1, Caudium will cache the
// result of this script for maximum performances
// and will not execute it a second time.
// As a result, If you give the argument
// ?reload=1 to your script, Caudium will
// reload it.
// This is useful to use cache for average
// content delivery unless you are doing
// developpement
int no_reload(object id)
{
if(!id->variables->reload)
return 1;
return 0;
}
// As this is a simple pike script (CGI like), this function
// will be called by Caudium and should return a string that
// will be display to the client's browser.
// It can also return a mapping containing all the HTTP response
// (headers + text)
mapping parse(object id)
{
// We randomly return one of the file we list in the FILELIST file
// (relative to BASEDIR directory).
// http_redirect will send a HTTP 301 header telling the browser
// where to get randomly selected file.
return http_redirect(BASEDIR + files[random(sizeof(files))],id);
}
But you can also create some powerful scripts:
Example 6-5. A script for the power user.
inherit "caudiumlib";
string|mapping|object parse( object id )
{
id->my_fd->write(id->clientprot + " 200 Ok\r\n");
id->my_fd->write("Server: Caudium !\r\n");
id->my_fd->write("Expires: 0\r\n");
id->my_fd->write("Content-Type: text/html\r\n");
id->my_fd->write("pragma: no-cache\r\n\r\n");
id->my_fd->set_id( ({ id->my_fd }) );
id->my_fd->set_nonblocking(0,send_data);
return http_pipe_in_progress();
}
void send_data(array (object) id)
{
id[0]->write("<pre>");
id[0]->write("test......................\n");
id[0]->write("test......................\n");
id[0]->write("test......................\n");
id[0]->write("sleep for 10 sec\n");
sleep(10);
id[0]->write("Done</pre>");
id[0]->close();
destruct(id[0]);
}
This example uses non-blocking sockets. my_fd is the file descriptor of the
HTTP socket. Here we change the type of the HTTP socket from blocking sockets
(default type) to non-blocking sockets. Non-blocking sockets are sockets that
won't block the program waiting for data. Instead, a read and write function
(the so-called callback functions) will be called automatically when there is
some data to read or write to the HTTP socket. Moreover, we return here a
special function, http_pipe_in_progress. This is because as the HTTP socket
is set to non-blocking, Caudium won't be able to wait for processing the HTTP
stuff like headers and so on. So we have to tell it not to wait for us and
send a http_pipe_in_progress.
This mechanism is very useful when you have to do some communication with
slow sockets on a single process server (multi-threaded one). In the case of
a single process, when you wait for a socket it is all the server, which will
wait. So all your users will be stalled. With non blocking sockets there is
no problem anymore; the server won't wait for each socket. Example of such
code includes CAMAS IMAP/NNTP clients. If you don't understand, don't worry,
you usually don't have to understand these mechanisms.
However, the Pike script allows you to write some complex code it is not
well suited for big projects. If this is the case, read the next paragraph
and enjoy.
Note The Caudium API is available at [http://caudium.net/] http://caudium.net
/. You should also read the Roxen 1.3 PDF available at [http://
caudium.info/] http://caudium.info/. Pike scripts are blocking, and
allow your users to run scripts with the same privilege as the server.
Blocking means that the server will be stalled if a socket from a pike
script is stalled (usually waiting for something). This applies even if
you use non-blocking sockets in your script. You don't have this problem
with modules.
-----------------------------------------------------------------------------
6.4. Your first module
With a custom module you can do all sorts of things:
  *  You can create a professional quality administration center very
easily.
  *  You don't need any more "&" symbols in the URL.
  *  You can also use per user variables, also known as session variables.
  *  You'll get better performance since the module is part of the server.
  *  You can separate big projects into different modules, and do calls
between different modules. This way, your project is not a big complex of
messy code, but a set of simple, easy to extend code modules.
  *  You can separate data from code by using tags and containers. This also
allows you to delegate the appearance to your webmaster, and lets you
focus on the important code.
  *  You can easily share your code with the Caudium community. If your code
is good and useful, it can become part of the Caudium distribution. This
way more people will test it, you will have more feedback, and some
people may help you with your project, and may even maintain it.
There are different types of modules, for example:
  *  Location:
This is the most common module, your code is called when the user hits
the URL you specify in the mount point.
  *  Parser:
Your code is called when Caudium parse a file containing the tags and/
or containers you define.
  *  Authentication:
Used to authenticate users with, for example, LDAP, shadow, or SQL.
  *  Directory:
For indexing files in a directory.
  *  First module:
Module that is called just after the authentication module, thus
letting you handle the whole request before normal processing.
There are other module types. For a complete reference see the Roxen 1.3
Programmer's Guide at [http://caudium.info/] http://caudium.info/.
For an example on how to write a container, see fnord.pike in /Caudium/
sources. Because the location module is a must, here is another example:
Example 6-6. A sample module.
// It is intended to show a simple example of a location module.
// This module output the result of the who(1) command. It is not meant to
// be really useful since it would be better to do a <who /> tag thus
// having data in the HTML files and code here
// This variable is shown in the configuration interface as the
// version of the module.
string CVS_version = "$Id";
// Tell Caudium that this module is 'thread safe', that is, there is no
// request-specific data in global variables.
int thread_safe=1;
#include <module.h>
inherit "module";
// for the http_string_answer API
inherit "caudiumlib";
// Documentation:
constant module_type = MODULE_LOCATION;
constant module_name = "Who";
constant module_doc = "Send the result of the who(1) command ";
constant module_unique = 1;
// The constructor of this module.
// This function is called each time you/Caudium load the module
void create()
{
defvar("location", "/who", "Mount point", TYPE_LOCATION,
"The mount point of this module");
/* each string have to be on a single
line, don't do: "The mount point of
this module".
You can however do "The mount point of "
"this module";
*/
defvar("path2who", "/usr/bin/who",
"Path to the who command", TYPE_FILE);
defvar("options2who", "-a",
"Options given to who", TYPE_STRING);
defvar("codebeforewho", "<html><body><p>",
"The code to output before who", TYPE_STRING);
defvar("codeafterwho", "</p></body></html>", "The code to output after who",
TYPE_STRING);
}
// This function is called when a user access mount point
// path is the path to the URL he used
// id contains Caudium global variables such as browser name,...
mixed find_file(string path, object id)
{
// get the contents of the CIF. variables path2who and options2who
// and put a single space between it.
string command = QUERY(path2who)+" "+QUERY(options2who);
// this will write the result of command to the debug log file
// very useful for debug
write(sprintf("command=%s\n", command));
string result = Process.popen(command);
// replacing \n by \n<br /> for better output
result = replace(result, "\n","\n<br />");
return http_string_answer(QUERY(codebeforewho)+result+QUERY(codeafterwho));
}
Put this code in ../local/modules/who.pike relative to /usr/local/caudium/
server in our example. Log into the CIF., if it is not the case and go into
the main Action tab -> Cache -> Flush caches. Check the Module cache check
the box and press Next, then OK.
Come back to the main Virtual servers tab and choose one of your servers.
Do Add module and select the who module. If you don't have the who module,
check your events log.
You don't need to compile to have a working module. You don't even need to
restart the web server. When you develop a module and change the code every
30 seconds, you just have to push the Reload button to get the changes. It
takes about one second and if there was a compilation error the old copy
remains for users.
-----------------------------------------------------------------------------
6.5. How to use a backtrace
A backtrace is text that will show you where your program come before the
error. This is very useful for developers when they debug. The best is to
take an example. Did you try the who module at the end of Section 6.4? If so
take it and check it works. Now change the line string command = QUERY
(path2who)+" "+QUERY(options2who); to string command = 0;. This will create
an error because we put an int into a string. If we want to do that, we have
to cast it (for example, use (string) 0). If you have not done it yet, press
the More options button in the CIF. and reload the module. Check that the
Global Variables -> show_internals option is set to yes, and try your module.
You will have an error which should look like this:
Caudium version: Caudium (Caudium/1.2.0)
Requested URL: /who
Error: Sprintf: Wrong type for argument 2: expected string, got int.
../local/modules/who.pike:76:
CaudiumModule(Who,My first virtual server)->find_file("",object)
base_server/configuration.pike (version 1.91):1587:
Configuration(My first virtual server)->low_get_file(object,0)
base_server/configuration.pike (version 1.91):1779:
Configuration(My first virtual server)->get_file(object,0)
base_server/configuration.pike (version 1.91):1760:
Configuration(My first virtual server)->handle_request(object)
protocols/http.pike (version 1.71):1549: unknown function()
protocols/http.pike (version 1.71):1610:
unknown function(0,"GET /who HTTP/1.1\r\nHost: localhost\r\nUser-Agent:
Mozilla/5.0 (X11; U; Linux i686; en-US; rv:0.9.8)
Gecko/20020214\r\nAccept: text/xml,application/xml,
application/xhtml+xml,text/html;q=0.9,text/plain"+[246])
/usr/local/pike/7.2.262/lib/modules/Stdio.pmod/module.pmod
(version 1.114):683:
Stdio.File("socket", "127.0.0.1 1260", 777 /* fd=-1 */)
->__stdio_read_callback()
This seems awful but it is not. The first line is the error in itself:
"Error: Sprintf: Wrong type for argument 2: expected string, got int."
The next line "../local/modules/who.pike:76:
CaudiumModule(Who,My first virtual server)->find_file("",object)"
is the program (../local/modules/who.pike at line 76)
where the error occurred. find_file is the name of the function where the
error occurred and you have also the arguments given to it. If you use the
source, you see mixed find_file(string path, object id). So here path="" and
id=object [3]. Next line is the function (low_get_file in configuration.pike)
that has called find_file in who.pike. You also have its arguments and so on.
This backtrace is very useful when the error doesn't come directly from your
code but from another code before.
-----------------------------------------------------------------------------
6.6. How to print something to debug log file
With Caudium you can output something to the web page or to the debug log
file located in ../logs/debug/default.*. This way the end-user will not see
any line you can output in your debug log file. Sending output to the debug
log file is simple, just write to stdout:
write("my message to log file\n");
It is also usually useful to use sprintf to format what you want to output:
int i = 2; write(sprintf("i=%d\n", i));
This line will output i=2, but it is better when you output array or mapping,
as Pike is able to print them in a human-comprehensible format:
array a = ({ "test", "test2", 2 }); write(sprintf("a=%O\n", a));
Which will output:
a = ({ /* 2 elements */
"test",
"test2"
})
Note the %O format is very useful since it can output any type from int to
mapping. The only type you can't format is object.
-----------------------------------------------------------------------------
Chapter 7. How to help the Caudium community
Caudium is a great product, but even with the best programmers in the world
it would be nothing if you didn't help us. This doesn't necessarily mean
working for Caudium twelve hours a day but thinking of it for a few seconds.
The next paragraph is mainly for users who just want to help us without
getting involved too much.
-----------------------------------------------------------------------------
7.1. How to promote Caudium
Caudium, and Roxen problems are not technical. Instead, they are
advertising and marketing. Caudium needs to become recognized. It could the
best product in the world, but if nobody knows, it will not be used. To help
Caudium to become recognized for its quality there are some simple things we
can do together:
  *  Try it, and give us feedback about your experience.
  *  Write some documentation. Without documentation, a project is useless.
  *  Recommend Caudium to some people you know. You don't really have to
tell them to try it now or they will die, just tell him about it. If
other people tell them the same thing, chances are that they will install
it. When these people install Caudium, they will look for documentation.
  *  Mention Caudium in newsgroups/web sites telling them what you think of
it.
  *  Translate documentation.
If you do this, you will help promote Caudium's success. Remember, one of
Caudium disadvantages is that the community is too small right now.
The next paragraph is for people who want to get involved a little more,
but don't have lot of time, and/or are not technically minded.
-----------------------------------------------------------------------------
7.2. How to write documentation
There are two types of documentation needed for Caudium:
  *  Press articles.
You can write press articles about Caudium.
Note Note for French writers:
  You can contact us for that.
This type of documentation is usually not really helpful since few in
the community will read it. It is useful mainly for advertising (even if
you made a very technical article, this is useful).
  *  Documentation available from Internet.
This type of documentation is a must; Caudium can't exist without it.
This documentation will help Caudium's newbies, and will also be useful
for developers. One good way to start with Caudium is using the Roxen 1.3
documentation. The developers should also see the autodoc. These are
in-line documents made in the sources, and available as formatted HTML
output at [http://caudium.net/] http://caudium.net/.
There is also a lack for a more in-depth documentation for developer.
Examples include how to code non-blocking sockets, how to use a
backtrace, how to use the do_output_tag, and when should I put
thread_safe=1. I remember spending hours trying to understand some of
these things on IRC without any documentation available. This sort of
documentation should be written by one of the top developers.
This documentation is written using XSLT, but if you don't know it,
that's not a problem. Give us whatever format you want, we will translate
it. It is the same for the language. If you don't speak English, you can
write it in your own language and we will translate. We will also
proof-read your work carefully in order to correct any typos or
inaccuracies you might leave.
To write this type of documentation, contact the person in charge of
the documentation project, ice at caudium dot net.
-----------------------------------------------------------------------------
7.3. How to get a CVS account
Unlike other projects, it's relatively not much hassle to get access to
Caudium cvs tree. Even if you are a beginner you can have cvs access; we just
ask you not to change Caudium's core at the beginning.
To get a CVS account, come on IRC or send a mail to kiwi at caudium dot net
and explain your plan.
-----------------------------------------------------------------------------
7.4. How to test Caudium
There is a test suite for Caudium written in Expect which uses TCL and
DejaGNU. If you want to use it, fetch it from Caudium's CVS repository with
the -P testsuite option (the information on this CVS repository is on [http:/
/caudium.net/] http://caudium.net/.) Note that this test suite is not
maintained, and needs some work.
-----------------------------------------------------------------------------
7.5. How to send a bug report
To send a bug report, copy/paste the error from Caudium's log file
(including backtrace, see Section 6.5), your configuration, and the context
in which it happened.
Go to [http://caudium.net/] http://caudium.net/ and choose bug tracking on
the left and follow the instructions.
-----------------------------------------------------------------------------
Chapter 8. Revision History/Credits/The End
8.1. Revision History
  * Version 2.2 : September 20, 2002
Added images and icons.
Better use of Docbook.
Updates in the FreeBSD ports section.
Few more fixes.
  * Version 2.1 : June 26, 2002
Little language and cosmetic corrections.
Added the script for image selection in the your first Pike script.
Corrections in the FreeBSD ports section.
The file is now well-formed XML.
  * Version 2.0 : June 14, 2002
LDP Review of documentation.
Added cross reference to full GFDL in Appendix A.
Converted to Docbook XML 4.1.2.
Removed editing notations that are corrected.
Corrected links to LDP (Linux Documentation Project).
Made sentence level corrections-spelling, grammar, etc.
  * Version 1.0 : June 6, 2002
Initial Release
Submitted to the LDP
  * Version 0.91 : May 22, 2002
The SGML source is now the authoritative source
The SGML source is now correctly indented
Many little SGML changes in the document
Added the Upgrading Caudium paragraph
Added a note about the start script config-dir option
  * Version 0.9 : May 7, 2002
Better HTML conformance to avoid Caudium crash on caudium.info.
Inserting the notes from Kiwi, Grendel and other into the document.
Removed all TODO and #define sections.
Completed the test suite section.
Added the contributors section.
Now docbook2ps and docbook2pdf correctly parse the SGML file.
  * Version 0.05 : April 4, 2002
This HOWTO is in Docbook format. Thanks to Thomas Marteau.
  * Version 0.04 : March 26, 2002
Added Introduction and license.
Added a note in "Your first pike script".
Corrected typo in paragraph number.
Re-organization of the document.
  * Version 0.03 : March 22, 2002
More Caudium disadvantages and some useful corrections from people at the
Caudium general mailing list.
Answers:
How to get UltraLog working.
How to benchmark a web server.
How to use a backtrace.
How to print something to debug log file.
How to get CAMAS from cvs/source.
  * Version 0.02 : March 18, 2002
Minor correction in other answers.
Answers:
How to run Caudium as a non-privileged user.
How to secure Caudium.
How to tune Caudium for best performance.
How to get packages for Debian GNU/Linux.
How to get packages for FreeBSD.
How to get packages for Solaris.
How to use your own fonts.
How to help Caudium Community.
  * Version 0.01 : March 11, 2002
Initial revision. Plain text format.
-----------------------------------------------------------------------------
8.2. Credits and contributors
Here is the list of people that helped me in one way or another to get this
HOWTO written:
Joe Follansbee <joef at compelinteractive dot com>
Grammar, spelling and syntax cleanup.
Bill Welliver <Bill.Welliver at fairchildsemi dot com>
Minor changes.
Chris Davies <mcd at daviesinc dot com>
Major contribution to the Caudium's disadvantages, many little fixes and
spelling corrections.
Martin Friese <mf at bauko dot bv dot tu-berlin dot de>
Update in the platform section.
Xavier Beaudouin <kiwi at oav dot net>
All tuning sections, cosmetics changes.
Marek Habersack <grendel at caudium dot net>
Minor fixes and latex conversion.
Thomas Marteau <marteaut at tuxfamily dot org>
Minor fixes and SGML conversion.
John Wenger <JohnWenger at EarthLink dot Net>
Editing, review and comments.
-----------------------------------------------------------------------------
8.3. The End
Thanks for reading. I hope this HOWTO will help you discover Caudium's power.
And remember this quotation:
  Documentation is like sex: when it is good, it is very, very  
good; and when it is bad, it is better than nothing.
--Dick Brandon  
If you have any questions about this documentation, contact me at <vida at
caudium dot net> or the Caudium general mailing list at <general at oav dot
net>
-----------------------------------------------------------------------------
Appendix A. GNU Free Documentation License
Version 1.1, March 2000
Copyright (C) 2000 Free Software Foundation, Inc. 59 Temple Place, Suite
330, Boston, MA 02111-1307 USA Everyone is permitted to copy and
distribute verbatim copies of this license document, but changing it is
not allowed.
-----------------------------------------------------------------------------
A.1. PREAMBLE
The purpose of this License is to make a manual, textbook, or other written
document "free" in the sense of freedom: to assure everyone the effective
freedom to copy and redistribute it, with or without modifying it, either
commercially or noncommercially. Secondarily, this License preserves for the
author and publisher a way to get credit for their work, while not being
considered responsible for modifications made by others.
This License is a kind of "copyleft", which means that derivative works of
the document must themselves be free in the same sense. It complements the
GNU General Public License, which is a copyleft license designed for free
software.
We have designed this License in order to use it for manuals for free
software, because free software needs free documentation: a free program
should come with manuals providing the same freedoms that the software does.
But this License is not limited to software manuals; it can be used for any
textual work, regardless of subject matter or whether it is published as a
printed book. We recommend this License principally for works whose purpose
is instruction or reference.
-----------------------------------------------------------------------------
A.2. APPLICABILITY AND DEFINITIONS
This License applies to any manual or other work that contains a notice
placed by the copyright holder saying it can be distributed under the terms
of this License. The "Document", below, refers to any such manual or work.
Any member of the public is a licensee, and is addressed as "you".
A "Modified Version" of the Document means any work containing the Document
or a portion of it, either copied verbatim, or with modifications and/or
translated into another language.
A "Secondary Section" is a named appendix or a front-matter section of the
Document that deals exclusively with the relationship of the publishers or
authors of the Document to the Document's overall subject (or to related
matters) and contains nothing that could fall directly within that overall
subject. (For example, if the Document is in part a textbook of mathematics,
a Secondary Section may not explain any mathematics.) The relationship could
be a matter of historical connection with the subject or with related
matters, or of legal, commercial, philosophical, ethical or political
position regarding them.
The "Invariant Sections" are certain Secondary Sections whose titles are
designated, as being those of Invariant Sections, in the notice that says
that the Document is released under this License.
The "Cover Texts" are certain short passages of text that are listed, as
Front-Cover Texts or Back-Cover Texts, in the notice that says that the
Document is released under this License.
A "Transparent" copy of the Document means a machine-readable copy,
represented in a format whose specification is available to the general
public, whose contents can be viewed and edited directly and
straightforwardly with generic text editors or (for images composed of
pixels) generic paint programs or (for drawings) some widely available
drawing editor, and that is suitable for input to text formatters or for
automatic translation to a variety of formats suitable for input to text
formatters. A copy made in an otherwise Transparent file format whose markup
has been designed to thwart or discourage subsequent modification by readers
is not Transparent. A copy that is not "Transparent" is called "Opaque".
Examples of suitable formats for Transparent copies include plain ASCII
without markup, Texinfo input format, LaTeX input format, SGML or XML using a
publicly available DTD, and standard-conforming simple HTML designed for
human modification. Opaque formats include PostScript, PDF, proprietary
formats that can be read and edited only by proprietary word processors, SGML
or XML for which the DTD and/or processing tools are not generally available,
and the machine-generated HTML produced by some word processors for output
purposes only.
The "Title Page" means, for a printed book, the title page itself, plus such
following pages as are needed to hold, legibly, the material this License
requires to appear in the title page. For works in formats which do not have
any title page as such, "Title Page" means the text near the most prominent
appearance of the work's title, preceding the beginning of the body of the
text.
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A.3. VERBATIM COPYING
You may copy and distribute the Document in any medium, either commercially
or noncommercially, provided that this License, the copyright notices, and
the license notice saying this License applies to the Document are reproduced
in all copies, and that you add no other conditions whatsoever to those of
this License. You may not use technical measures to obstruct or control the
reading or further copying of the copies you make or distribute. However, you
may accept compensation in exchange for copies. If you distribute a large
enough number of copies you must also follow the conditions in section 3.
You may also lend copies, under the same conditions stated above, and you may
publicly display copies.
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A.4. COPYING IN QUANTITY
If you publish printed copies of the Document numbering more than 100, and
the Document's license notice requires Cover Texts, you must enclose the
copies in covers that carry, clearly and legibly, all these Cover Texts:
Front-Cover Texts on the front cover, and Back-Cover Texts on the back cover.
Both covers must also clearly and legibly identify you as the publisher of
these copies. The front cover must present the full title with all words of
the title equally prominent and visible. You may add other material on the
covers in addition. Copying with changes limited to the covers, as long as
they preserve the title of the Document and satisfy these conditions, can be
treated as verbatim copying in other respects.
If the required texts for either cover are too voluminous to fit legibly, you
should put the first ones listed (as many as fit reasonably) on the actual
cover, and continue the rest onto adjacent pages.
If you publish or distribute Opaque copies of the Document numbering more
than 100, you must either include a machine-readable Transparent copy along
with each Opaque copy, or state in or with each Opaque copy a
publicly-accessible computer-network location containing a complete
Transparent copy of the Document, free of added material, which the general
network-using public has access to download anonymously at no charge using
public-standard network protocols. If you use the latter option, you must
take reasonably prudent steps, when you begin distribution of Opaque copies
in quantity, to ensure that this Transparent copy will remain thus accessible
at the stated location until at least one year after the last time you
distribute an Opaque copy (directly or through your agents or retailers) of
that edition to the public.
It is requested, but not required, that you contact the authors of the
Document well before redistributing any large number of copies, to give them
a chance to provide you with an updated version of the Document.
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A.5. MODIFICATIONS
You may copy and distribute a Modified Version of the Document under the
conditions of sections 2 and 3 above, provided that you release the Modified
Version under precisely this License, with the Modified Version filling the
role of the Document, thus licensing distribution and modification of the
Modified Version to whoever possesses a copy of it. In addition, you must do
these things in the Modified Version:
A. Use in the Title Page (and on the covers, if any) a title distinct from
that of the Document, and from those of previous versions (which should,
if there were any, be listed in the History section of the Document). You
may use the same title as a previous version if the original publisher of
that version gives permission.
B. List on the Title Page, as authors, one or more persons or entities
responsible for authorship of the modifications in the Modified Version,
together with at least five of the principal authors of the Document (all
of its principal authors, if it has less than five).
C. State on the Title page the name of the publisher of the Modified
Version, as the publisher.
D. Preserve all the copyright notices of the Document.
E. Add an appropriate copyright notice for your modifications adjacent to
the other copyright notices.
F. Include, immediately after the copyright notices, a license notice giving
the public permission to use the Modified Version under the terms of this
License, in the form shown in the Addendum below.
G. Preserve in that license notice the full lists of Invariant Sections and
required Cover Texts given in the Document's license notice.
H. Include an unaltered copy of this License.
I. Preserve the section entitled "History", and its title, and add to it an
item stating at least the title, year, new authors, and publisher of the
Modified Version as given on the Title Page. If there is no section
entitled "History" in the Document, create one stating the title, year,
authors, and publisher of the Document as given on its Title Page, then
add an item describing the Modified Version as stated in the previous
sentence.
J. Preserve the network location, if any, given in the Document for public
access to a Transparent copy of the Document, and likewise the network
locations given in the Document for previous versions it was based on.
These may be placed in the "History" section. You may omit a network
location for a work that was published at least four years before the
Document itself, or if the original publisher of the version it refers to
gives permission.
K. In any section entitled "Acknowledgements" or "Dedications", preserve the
section's title, and preserve in the section all the substance and tone
of each of the contributor acknowledgements and/or dedications given
therein.
L. Preserve all the Invariant Sections of the Document, unaltered in their
text and in their titles. Section numbers or the equivalent are not
considered part of the section titles.
M. Delete any section entitled "Endorsements". Such a section may not be
included in the Modified Version.
N. Do not retitle any existing section as "Endorsements" or to conflict in
title with any Invariant Section.
If the Modified Version includes new front-matter sections or appendices that
qualify as Secondary Sections and contain no material copied from the
Document, you may at your option designate some or all of these sections as
invariant. To do this, add their titles to the list of Invariant Sections in
the Modified Version's license notice. These titles must be distinct from any
other section titles.
You may add a section entitled "Endorsements", provided it contains nothing
but endorsements of your Modified Version by various parties--for example,
statements of peer review or that the text has been approved by an
organization as the authoritative definition of a standard.
You may add a passage of up to five words as a Front-Cover Text, and a
passage of up to 25 words as a Back-Cover Text, to the end of the list of
Cover Texts in the Modified Version. Only one passage of Front-Cover Text and
one of Back-Cover Text may be added by (or through arrangements made by) any
one entity. If the Document already includes a cover text for the same cover,
previously added by you or by arrangement made by the same entity you are
acting on behalf of, you may not add another; but you may replace the old
one, on explicit permission from the previous publisher that added the old
one.
The author(s) and publisher(s) of the Document do not by this License give
permission to use their names for publicity for or to assert or imply
endorsement of any Modified Version.
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A.6. COMBINING DOCUMENTS
You may combine the Document with other documents released under this
License, under the terms defined in section 4 above for modified versions,
provided that you include in the combination all of the Invariant Sections of
all of the original documents, unmodified, and list them all as Invariant
Sections of your combined work in its license notice.
The combined work need only contain one copy of this License, and multiple
identical Invariant Sections may be replaced with a single copy. If there are
multiple Invariant Sections with the same name but different contents, make
the title of each such section unique by adding at the end of it, in
parentheses, the name of the original author or publisher of that section if
known, or else a unique number. Make the same adjustment to the section
titles in the list of Invariant Sections in the license notice of the
combined work.
In the combination, you must combine any sections entitled "History" in the
various original documents, forming one section entitled "History"; likewise
combine any sections entitled "Acknowledgements", and any sections entitled
"Dedications". You must delete all sections entitled "Endorsements."
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A.7. COLLECTIONS OF DOCUMENTS
You may make a collection consisting of the Document and other documents
released under this License, and replace the individual copies of this
License in the various documents with a single copy that is included in the
collection, provided that you follow the rules of this License for verbatim
copying of each of the documents in all other respects.
You may extract a single document from such a collection, and distribute it
individually under this License, provided you insert a copy of this License
into the extracted document, and follow this License in all other respects
regarding verbatim copying of that document.
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A.8. AGGREGATION WITH INDEPENDENT WORKS
A compilation of the Document or its derivatives with other separate and
independent documents or works, in or on a volume of a storage or
distribution medium, does not as a whole count as a Modified Version of the
Document, provided no compilation copyright is claimed for the compilation.
Such a compilation is called an "aggregate", and this License does not apply
to the other self-contained works thus compiled with the Document, on account
of their being thus compiled, if they are not themselves derivative works of
the Document.
If the Cover Text requirement of section 3 is applicable to these copies of
the Document, then if the Document is less than one quarter of the entire
aggregate, the Document's Cover Texts may be placed on covers that surround
only the Document within the aggregate. Otherwise they must appear on covers
around the whole aggregate.
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A.9. TRANSLATION
Translation is considered a kind of modification, so you may distribute
translations of the Document under the terms of section 4. Replacing
Invariant Sections with translations requires special permission from their
copyright holders, but you may include translations of some or all Invariant
Sections in addition to the original versions of these Invariant Sections.
You may include a translation of this License provided that you also include
the original English version of this License. In case of a disagreement
between the translation and the original English version of this License, the
original English version will prevail.
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A.10. TERMINATION
You may not copy, modify, sublicense, or distribute the Document except as
expressly provided for under this License. Any other attempt to copy, modify,
sublicense or distribute the Document is void, and will automatically
terminate your rights under this License. However, parties who have received
copies, or rights, from you under this License will not have their licenses
terminated so long as such parties remain in full compliance.
-----------------------------------------------------------------------------
A.11. FUTURE REVISIONS OF THIS LICENSE
The Free Software Foundation may publish new, revised versions of the GNU
Free Documentation License from time to time. Such new versions will be
similar in spirit to the present version, but may differ in detail to address
new problems or concerns. See [http://www.gnu.org/copyleft/] http://
www.gnu.org/copyleft/.
Each version of the License is given a distinguishing version number. If the
Document specifies that a particular numbered version of this License "or any
later version" applies to it, you have the option of following the terms and
conditions either of that specified version or of any later version that has
been published (not as a draft) by the Free Software Foundation. If the
Document does not specify a version number of this License, you may choose
any version ever published (not as a draft) by the Free Software Foundation.
-----------------------------------------------------------------------------
A.12. How to use this License for your documents
To use this License in a document you have written, include a copy of the
License in the document and put the following copyright and license notices
just after the title page:
Copyright (c) YEAR YOUR NAME. Permission is granted to copy, distribute
and/or modify this document under the terms of the GNU Free Documentation
License, Version 1.1 or any later version published by the Free Software
Foundation; with the Invariant Sections being LIST THEIR TITLES, with the
Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST. A
copy of the license is included in the section entitled "GNU Free
Documentation License".
If you have no Invariant Sections, write "with no Invariant Sections" instead
of saying which ones are invariant. If you have no Front-Cover Texts, write
"no Front-Cover Texts" instead of "Front-Cover Texts being LIST"; likewise
for Back-Cover Texts.
If your document contains nontrivial examples of program code, we recommend
releasing these examples in parallel under your choice of free software
license, such as the GNU General Public License, to permit their use in free
software.
Notes
[1] To identify you can use lsof(8). If you want to know which programs
listen on port 80 just issue the following command as root
Note You need to be root if lsof has been compiled with the HASSECURITY
option which is the default for some GNU/Linux distributions
:
# lsof -i TCP:80
Here is the result:
COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME
caudium 1001 root 12u IPv4 3993 TCP *:www (LISTEN)
[2] In fact you can... just compile PHP for Caudium :)
[3] Pike can't display contents of an object but can display any other
types.
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