Understanding the Node.js Platform

understanding
the

platform
Domenic Denicola
http://domenicdenicola.com
@domenic

Domenic Denicola
@domenic
https://npmjs.org/profile/domenicdenicola
http://github.com/domenic
http://github.com/NobleJS

@domenic

agenda

how to node
why to node
coding time

@domenic

why to node

new and shiny
fast
scalable
low-level
community

@domenic

let’s look at the most-used
node.js packages.

@domenic

 socket.io: used by 306 other packages
 redis: 259 (hiredis: 70)
 stylus: 148 (less: 134)
 mongodb: 144 (mongoose: 135)

@domenic

New HTTP Parser
I've implemented a new HTTP/1.1 request and response parser by hand. (My
previous parser was written with the help of Ragel.) It requires 124 bytes per
HTTP connection, makes zero allocations, has no dependencies, is nearly optimal
in its use of CPU instructions, interruptible on any character, has extensive tests,
and is MIT licensed.

README

http_parser.h

http_parser.c

(Only one user at the moment: I've just merged it into Node.)

http://four.livejournal.com/1033160.html
@domenic

q: what do web servers actually do?

a: i/o

@domenic

Response.Write("hello, world!");

@domenic

move_uploaded_file(
$_FILES['userphoto']['tmp_name'],
"/var/www/userphotos/" . $_POST['username']
);

@domenic

import memcache

mc = memcache.Client(['127.0.0.1:11211'])

mc.set("heavily_used_data", "data")
value = mc.get("more_data")

@domenic

class Post < ActiveRecord::Base
attr_accessible :content, :name, :title

validates :name, :presence => true
validates :title, :presence => true
end

@domenic

move this stuff out of the context of
the web for a moment

@domenic

q: how do last-generation web
servers fix this problem?

a: threads
@domenic

let’s talk about threads.

@domenic

they suck.

the end.

@domenic

q: how does node solve this problem?

a: javascript
@domenic

My next project
I'm going to write a special thin web server tied to the V8 javascript interpreter
The web server will execute javascripts in response to requests in real-time.
The beautiful thing about this is that I can lock the users in an evented box where they have no choice
but to be fast. They cannot touch the disk. They cannot access a database with some stupid library that
blocks because they have no access to blocking I/O. They cannot resize an image by linking imagemagick
into the web server process (and thus slowing down/blocking the entire thing). They cannot crash it
because they are very limited in what they can do.
Why javascript?
 because its bare and does not come with I/O APIs
 web developers use it already
 DOM API is event-based. Everyone is already used to running without threads and on an event loop
already.
I think this design will be extremely efficient and support very high loads. Web requests are transformed
into mysql, memcached, AMQP requests and then return to the event loop.
Web developers need this sort of environment where it is not possible for them to do stupid things. Ruby,
python, C++, PHP are all terrible languages for web development because they allow too much freedom.

http://four.livejournal.com/963421.html
@domenic

javascript has never had
blocking i/o

@domenic

javascript has never had
more than one thread

@domenic

instead we use callbacks
and events

@domenic

$.get("http://nodejs.org", function (data) {
document.body.innerHTML = data;
});

@domenic

var dbReq = indexedDB.open("my-database");

dbReq.addEventListener("success", function () {
var dbConnection = dbReq.result;
});

@domenic

it’s the same in node

@domenic

fs.readFile("/etc/passwd", function (err, data) {
console.log(data);
});

@domenic

request.on("data", function (chunk) {
response.write(chunk);
});

@domenic

db.users.find({ name: "domenic" }, function (err, users) {
users.forEach(function (user) {
response.write(user);
});
});

@domenic

io.sockets.on("connection", function (socket) {
socket.emit("news", { hello: "world" });
socket.on("my other event", function (data) {
console.log(data);
});
});

@domenic

 STDIO  Timers  Process  Utilities
 Events  Domain  Buffer  Stream
 Crypto  TLS/SSL  String Decoder
 File System  Path  Net  UDP/Datagram
 DNS  HTTP  HTTPS  URL  Query Strings
 Punycode  Readline  REPL  VM
 Child Processes  Assertion Testing  TTY
 ZLIB  OS  Cluster

http://nodejs.org/docs/latest/api/
@domenic

that’s it.

that’s all you get.

@domenic

codingTime();
https://github.com/domenic/understanding-node

@domenic

Understanding the Node.js Platform

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