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Post by Ulas Gregory with Palo Alto IT Consulting, Ltd
What is a Web Server?
Before we get into the
particulars of Apache, let\'s talk about what a web
server is.
A web server is a program that runs
on a host computer (also, confusingly enough, called a web server) that serves
up web sites. In
other words, the web server program sits around awaiting
requests from visitors\' web browsers for objects it has in its possession,
and
then
sends these objects back for the visitor\'s viewing pleasure. Objects that
web servers can serve include HTML documents, plain
text, images, sounds,
video, and other forms of data.
These objects may not necessarily exist in
static form, but instead are generated
on-the-fly by programs run by the
server; CGI scripts are the most common of these programs.
Web servers and browsers
communicate using HTTP, Hypertext
Transfer
Protocol,
a simple but effective language for requesting and transmitting data over a
network. Thus, you\'ll sometimes hear web servers referred
to as HTTP servers.
Web servers come in various
shapes and sizes. They run under a variety of operating systems, have varying
levels of power
and complexity, and range in price from rather expensive to
free.
What's so special about Apache?
Apache is:
Powerful
Apache\'s performance and reliability is legendary.
Feature-Rich
The Apache
server sports a host of features, including: XML support,
server-side includes, powerful URL-rewriting, and virtual hosting, to name
but a few. We\'ll
be talking about some of these features in future articles.
Modular
-- Looking for a feature not implemented in the core Apache server?
Chances
are
you\'ll find a module that can add the functionality you need.
Extensible
-- Can\'t find a module that suits your purposes? Well, as Apache
is open
source,
you can write one yourself. In fact, you can even make changes to
the inner workings of Apache. All the information you need is right
there in
the
source code and numerous online resources. Share your patches or modules
with the community by making them open source as well!
Popular
-- At the time
of this writing, Apache holds a smidge under 60 percent of
the web server market.
And, yes, popularity does count; help
abounds and is
only a mailing list or newsgroup posting away......................
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Free
-- This is one
instance where you don\'t necessarily get what you pay for.
Where does Apache live?
Apache is maintained by the
Apache Software Foundation\'s Apache
Server Project at
http://www.apache.org.
Apache
Web Server
The Apache Web
server, for
those of you who haven\'t heard of it, is arguably the most popular Web server
in use on the Internet today. While
Microsoft contends that its Internet
Information Server (IIS) is making huge gains, it\'s still struggling in many
ways against Apache.
Why?
For
starters, you don\'t have
to be running Windows to run Apache. It was first developed on the various
Unix/Linux/BSD platforms, then recently ported to
Win32. Internet
Information Server, while a very good Web server on the NT
platform, is trapped in the \"Windows-only\" world. While IIS
has many handy
features, not everyone wants to run NT for their Web server\'s OS.
Another reason for Apache\'s
widespread acceptance is its overall
stability. While you can slow down an
Apache Web server (especially if you run tons of PERL/CGI scripts on it), you
can rarely, if
ever, kill one. The Apache Web server service is near
bombproof.
Lastly, it\'s relatively
fast. I say \"relatively\" as it\'s relative
to what you\'re doing with it. If
you\'re hosting a Web site with mostly static content, Apache is a fireball. If
you throw tons of CGI scripts at it,
while making database calls at the same
time, you\'re going to slow it down. Though much of the slowdown will come from
your scripts themselves,
and not Apache.
This article is going to
cover the basics of Apache configuration on Red Hat Linux 6.x-7.1, but fear
not; most of the Apache configuration features are cross
platform. That means
that if you make a modification to Apache on Linux, that same modification, or
one extremely similar, is available
on other various flavors of Linux using
the same syntax!
Getting
Apache
Apache is available from
http://www.apache.org. While you\'re
downloading the Apache package that\'s
appropriate for your Operating System,
be sure to grab the documentation.
If you\'re a Linux user, the
odds are in your favor that Apache has
been pre-installed. With the exception
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of desktop-centric
Linux such as Caldera, it\'s rare that you won\'t have the
Apache server installed.
During your Linux installation, if
you see an option
for \"Web services\" make sure to select it so that Apache will be installed.
If you\'re new to the
Unix/Linux/BSD world, I should warn
you about something. There are two types
of installation packages - source and binary. If you\'re new to the
Unix world, try to download a binary
format. A
binary
is the fully compiled version of the application that\'s ready to be
installed on your system.
A source package is just
that, it\'s the source code to the application.
This means you have to compile
it into an executable program all by yourself. One often messes up while
compiling an application. If you\'re
fortunate, you\'ll find your error
immediately. If you\'re unlucky, it could be hours, days or weeks before you
find out, and then you have to spend time re-compiling
it again to fix your
mistakes. Do yourself a favor when first learning Apache - find the binary
package for your OS.
You can learn the finer
points of compilation later.
Installing, and Running Apache
Those of you
running the RedHat Linux distribution may want to take
advantage of
RedHat\'s RPM (\"RedHat Package Manager\") system.
Almost identical to a binary, an RPM is further customized to play
nicely with
other RPMs and provide a consistent interface to
installing, updating, and removing binaries. They often entail a loss of
flexibility and
clarity -- for instance, it\'s not readily apparent where the
contents of some packages will end up.
That said, for
Linux newcomers or when
installing a small standard component, RPMs are
simple and reliable.
Bear in mind
that an Apache RPM may already be installed on your
system depending on how
Linux was originally installed on your computer. To find out, at the shell
prompt, type:
rpm
-qa | grep apache
If
you see
something
like apache-1.3.9xxx, an Apache RPM has already been installed and
you can skip on to
\"Starting
Apache\".
If you don\'t
have an Apache RPM, you must obtain one. RedHat 6.x
Onwards ships with apache-1.x.x-x.i386.rpm in the RedHat/RPMS directory
on
the installation CD. Or, point your Web browser at ....................
ftp://ftp.redhat.com/pub/redhat/current/i386/RedHat/RPMS
and pick yourself
up a copy. If you\'ve not already done so, you\'ll need to
become root. Navigate to the same directory as the .rpm file you obtained,
and
then
type the following command, substituting the name of the .rpm you\'re
using for apache-1.x.x-x.i386.rpm.
rpm
-ivh apache-1.x.x-x.i386.rpm
RPM should
grind away, displaying
its progress with a primitive ####### progress bar.
Barring any errors, you\'re done.
If you\'re
interested in knowing how to install Apache from scratch,
read on. Or you can
skip on to
Starting Apache.
Building
Apache from source
may seem a daunting proposition to newcomers,
but the Apache developers have
done a wonderful job of making the task about as simple as could be. Just
three more commands than a binary installation and you
skip the arduous task
of figuring out which binary is the right one for your particular operating
system. Let\'s give it a whirl, shall we?
Point
your Web browser at
http://www.apache.org/dist and
download the gzip\'d form of the current
version of
Apache.
Now let\'s uncompress that
archive using gunzip and tar. You should replace
the
apache_1.3.11.tar.gz
below with the name of the gzip\'d file
you
downloaded.
gunzip apache_1.3.11.tar.gz | tar xvf -
You should end up with an
apache_1.3.x directory,
x being the particular sub-version of Apache you downloaded.
Move into the
newly created directory.
cd apache_1.3.x
Now we\'ll use
the
the
configure and
make commands to
(you
guessed
it) configure, make, and install Apache. If you\'ve not already done
so, now would be the time to become root.
./configure
Your screen should
look
something
like:
# ./configure
Configuring for Apache, Version 1.3.11
...
Creating Makefile
Creating Configuration.apaci
in src
Creating
Makefile in src
+ configured for Linux platform
+ setting C compiler to gcc
+ setting C pre-processor to gcc -E
+ checking for system header files
+ adding selected
modules
+
checking sizeof various data types
+ doing sanity check on compiler and options
...
Next Post I will
include all the pkg add-ons for client-server pairing...to the LAN-Cloud....