Matt Gauger - Lamp vs. the world - MKE PHP Users Group - December 14, 2010

and is probably a far more
appropriate title.

Giving not just one talk,
not two, but three talks
in December!

Already gave:
Git & Github at Web414
blog.mattgauger.com/git-github-a-beginners-guide

Just go to: blog.mattgauger.com

MKE Ruby User’s Group:
What’s new & great in Rails 3
Dec 20th 7PM

Slides from this talk will be
online at blog.mattgauger.com
tomorrow (probably)

Simple agenda for tonight:
Webservers:
where we came from,
where we are now, and
where we’re going

All web sites (web apps)
have a need.

Let’s start with some basics.

A Request or Response is
made of 4 parts:

• Request line, such as GET /index.html
• Headers, such as Accept-Language: en
• An empty line
• An optional message body

A system of Verbs and
Nouns

for interacting with a web
resource.

Roy Fielding ﬁrst deﬁned REST
10 years ago in his dissertation
Architectural Styles and the
Design of Network-based
Software Architectures.

Since then, REST is often held as
the standard for usable, well-
designed, easy-to-integrate APIs.

A little history of
web servers

Created in February 1995
from the NCSA httpd 1.3
+ some patches

First ofﬁcial public release
of the Apache server
came in April 1995.

Apache has the legacy of
being one of the most
popular web servers.

You might also say that it is
limited by that legacy.

Where is that
behavior deﬁned?

Example /etc/apache2/sites-available/default
<VirtualHost *:80>
ServerAdmin webmaster@mattgauger.com
DocumentRoot /var/www/
<Directory /var/www/>
Options Indexes FollowSymLinks MultiViews
AllowOverride None
Order allow,deny
allow from all
</Directory>
ErrorLog /var/log/apache2/access.log combined
</VirtualHost>

Request comes in,
spin up a thread,
form a response,
send it back.

Apache’s method of
scaling:

Threads wait for
incoming connection

OS-level threads
incur a penalty

Each one has an
execution stack
that uses memory.

Context switching
between threads isn't
free.

Memory climbs and
climbs and the server
runs out

Swapping to disk
incurs a huge
penalty

This isn’t an ideal
way to scale

For massive
concurrency, we cannot
use an OS thread for
each connection.

You can throw more
CPUs, more RAM,
and more servers at it,
but it doesn’t solve it.

Sidenote: How does
PHP work on Apache?

PHP is a module to
Apache

It executes PHP
passed into it and
Apache sends a
response back

Execution stays within
Apache

The original idea for
PHP was to ﬁll in some
spots in HTML.

It was a HTML
“Preprocessor”

<?php $name = “Matt”; ?>
<p>My name is
<?php print $name; ?>
.</p>

Before it is sent back to the
browser.

So how do we get past
Apache’s scaling issues?

nginx can serve
HTML pages back to
a browser

but that isn’t why
you’d want to use it.

the event loop waits
and dispatches
events, or messages

the event causes an
event handler to be
called

event loops can be
highly concurrent

Its memory footprint
stays constant as #
of clients increases

nginx is intended to
be used as more of a
reverse proxy

What’s a ʎxoɹd
ǝsɹǝʌǝɹ?

Typically, reverse
proxies are used in front
of web servers.

Connections coming in
go to the reverse proxy
ﬁrst.

The proxy may deal with
the request itself, or pass
it off to some other
service.

nginx doesn’t handle
your PHP scripts for you

You have to tell it to give
PHP scripts to something
that can parse PHP

Here’s a default nginx
conﬁguration

Example /etc/nginx/sites-available/default
server {
listen 80 default;
server_name mattgauger.com;

index index.html;
root /var/www;

access_log /var/log/nginx/localhost.access.log;
}

FastCGI version of the same conﬁg
server {
listen 80;
server_name mattgauger.com;
index index.php;
root /var/www;

location ~* .php$ {
if (!-f $request_ﬁlename) {
return 404;
}

fastcgi_pass 127.0.0.1:9000;
}
}

Anything matching the
pattern ~* .php$
gets passed to FastCGI

FastCGI is actually a
service running on the
webserver on port 9000

In this sense, we can say
that FastCGI is a lot like
an application server in
other languages.

What does the app
server do?

Request comes in from
the reverse proxy

Or from some other means
(another server, data
transfers, APIs, RPCs, etc)

App servers run scripts,
but not in response to
incoming requests

The code is always
running, and when it
sees a request come in

It decides what it has to
do with that request

And it puts together an
HTTP Response

HTTP/1.1 200 OK
Date: Mon, 23 May 2005 22:38:34 GMT
Server: Etc.
Last-Modified: Wed, 08 Jan 2003 23:11:55 GMT
Etag: "3f80f-1b6-3e1cb03b"
Accept-Ranges: bytes
Content-Length: 438
Connection: close
Content-Type: text/html; charset=UTF-8
[blank line here!]
Response body.Neque porro quisquam est qui dolorem ipsum
quia dolor sit amet, consectetur, adipisci velit..."

Which is sent back as a
response to a browser,
or some JavaScript, or
whatever

Notice what’s going on
here.

We aren’t just serving
the contents of a ﬁle.

We aren’t just serving
the results of running a
PHP to ﬁll in some parts
of HTML either.

We’re writing an
application

But instead of having a
commandline interface
or GUI

This application uses
HTTP and REST.

Web applications are
typically structured with
something called MVC.

MVC = Model, View,
Controller

A full discussion on MVC
will have to wait.

But the important part is
that we’re not just
writing index.php

And index.php isn’t just
some preprocessor
code, ﬁlling out values in
an HTML template.

At this point in the talk,
I talked a lot about
where we’re going here,
which I argue is

node.js is written on top
of the Google V8 engine

Which is cool, because
you’re writing JavaScript
on the server-side.

node uses JavaScript’s
callback concept to
deﬁne applications

not just webapps;
other things are possible,
like DNS servers.

See this great talk by
node.js’s creator:
http://yhoo.it/e4Jx7i

I plan to write more blog
posts about webapps, web
servers, and application
servers in the future.

Matt Gauger - Lamp vs. the world - MKE PHP Users Group - December 14, 2010

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