Web
Servers: Understanding the Basics
SolveYourProblem.com Article Series: Web Site Design
There are a lot of web servers out there.
Whenever you go to a website, you're downloading it from a
web server. When you pay money to a web host, what you're really
doing is renting a space on their web server. The Internet
consists of millions of computers networked together, but it's
the servers that are providing all the information that makes
up the web you can't have a website unless it's on a server.
What is a Web Server?
A web server is really just a powerful computer they use
the same kinds of processors and memory that normal computers
use, but they have more of it. Servers usually run a Unix or
Unix-like operating system like Linux or BSD, but they can
just as easily run Windows.
What makes these computers servers isn't their hardware
it's the software they run. Web server software includes the
HTTP server itself, as well as databases and other things that
are needed to make a web server work however it needs to. This
is why different hosts offer different features: they have
different programs installed on their servers.
Web Servers Serve Files
The role of the web server, at its most basic level, is to
send people your files over HTTP. It has a hard disk (often
more than one) and stores your files like any other computer
if you don't upload a file called 'index.html', many servers
will list all your files for you instead of providing a web
page. It's the replacement of the index.html (named because
it is supposed to be an index of files) that creates the illusion
of everything on the server being one 'web site', instead of
a set of files linked together.
Web Servers Run Scripts
Of course, web servers don't always just serve the same files
over and over again. Sometimes they need to insert other information
into pages, especially information that comes from databases.
This is done with scripting languages like PHP and Perl the
server is told that it should give files that end in .pl or
.php to the appropriate script interpreters, and these interpreters
then tell the server what to send to the browser. This means
that dynamic websites can often be slow, as the server is having
to produce a different page for each visitor.
Virtual Servers and Dedicated Servers
When you buy web hosting, though, you're not necessarily getting
a whole server to yourself in fact, the chances are that
you're not, unless you're paying lots of money. Instead, you'll
be sharing a server with the hosts' other customers. You might
not realize this, since the server doesn't appear to have anything
on it that isn't yours, but the other customers are simply
being hidden from you you're using what is known as a 'virtual
server'.
For small websites, there isn't really any option other than
virtual servers: they're a great idea for letting resources
be shared among lots of websites that don't use much of the
server's power or space. If one of the sites does start growing,
though, you might find your website slowing down. Oddly enough,
this fact means that it's often better to find a host that
offers price plans with limits instead of one that offers 'unlimited'
disk space and bandwidth to each customer your website will
be much faster at the 'limited' host.
More Than You'd Think One thing that people don't often think about is that there's
more than one web server program out there. It's not really
visible to visitors, since they all do basically the same thing,
but there are lots of servers available, and they're all quite
different in the way they work. There are three main groups:
Apache. The open source Apache software is the most popular
server software out there, with around 70% of the market share.
Microsoft
servers. Microsoft are responsible for the various
versions of IIS (Internet Information Server) and PWS (Personal
Web Server), which altogether have around 20% of the market.
Sun
servers. Sun produce lots of servers, most notably the
Netscape-branded ones. The market share of these servers depends
on whether you count all sites (making it 3%) or just the actively
maintained ones (in which case it drops to less than 1%).
Source for statistics: netcraft.com.
Other servers available are mostly 'simple' servers that don't
have all the somewhat unnecessary features of these servers,
such as thttpd (the 't' is for tiny or turbo). There are literally
hundreds of them, but they have mostly negligible market share.
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SolveYourProblem.com : 2007
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