Node.js - As a networking tool

Node.js
As a networking tool

28.12.2010

About

Contributor Co-founder

Felix Geisendörfer
node.js driver node-formidable

Node's goal is to provide an easy way to build
scalable network programs.

Node.js

• Created by Ryan Dahl

• Google’s V8 JavaScript engine (no DOM)

• Module system, I/O bindings, Common Protocols

N
et
w
or
k

Hello World
Ed
it
io
n

$ cat hello.js
var net = require('net');
net.createServer(function(socket) {
socket.write('hello worldn');
socket.end();
}).listen(0x27C3);

$ node hello.js &
[1] 3591
$ nc localhost 10179
hello world

Why JavaScript?
3 Reasons

V8 (Chrome)

SpiderMonkey (Firefox) JavaScriptCore (Safari)

#2 - JS Engine Wars

Chakra (IE9) Carakan (Opera)

Blocking I/O

db.query('SELECT A');
console.log('query A done');

db.query('SELECT B');
console.log('query B done');

Time = SUM(A, B)

Non-Blocking I/O
db.query('SELECT A', function(result) {
console.log('query A done');
});

db.query('SELECT B', function(result) {
console.log('query B done');
});

Time = MAX(A, B)

libev
• An inﬁnite loop (event loop)

• Polls the OS for events (select, epoll,
kqueue, ...)

• Allows you to register watchers / callbacks
for the events you care about

Buffers

• Raw C memory allocation

• Similar to an array of integers

• Can be converted to and from JS strings

Buffers

buffer.write('Hello Buffer');

buffer.toString('utf-8');

buffer[0] = 23;

buffer.slice(10, 20);

Reverse Hello World
$ cat reverse_hello.js
socket.on('data', function(buffer) {
console.log(buffer);
});
}).listen(0x27C3);

$ node reverse_hello.js &
[1] 3523
$ echo "hello world" | nc localhost 10179
<Buffer 68 65 6c 6c 6f 20 77 6f 72 6c 64 0a>

“Streams are to time as arrays are to space.”
-- Jed Schmidt @ JSConf.eu

Streams

stream.write(new Buffer([0x27, 0xC3]);

stream.pause();

stream.resume();

stream.destroy();

Streams
stream

.on('drain', function() {})

.on('data', function(buffer) {})

.on('end', function() {});

Streams
$ cat echo.js
socket.pipe(socket);
}).listen(0x27C3);

$ node echo.js &
[1] 6207
$ nc 127.0.0.1 10179
Hi, how are you?
Hi, how are you?

pcap module
Snifﬁng data with node.js

pcap module

• Node.js bindings for libpcap

• Simple install: `npm install pcap`

• “Scriptable tcpdump”

pcap module
$ cat pcap.js
var util = require('util');
var pcap = require('pcap');
var filter = 'tcp port '+0x27C3;
var session = pcap.createSession('lo0', filter);

session.on('packet', function(packet) {
packet = pcap.decode.packet(packet);
console.log(pcap.print.packet(packet));

if (packet.link.ip.tcp.data) {
util.print(packet.link.ip.tcp.data.toString());
}
});

pcap module
$ node hello.js > /dev/null &
[1] 3592
$ sudo node pcap.js &
[2] 3593
$ nc 127.0.0.1 10179 > /dev/null
loopback 127.0.0.1:54078 -> 127.0.0.1:10179 TCP len 64 [syn]
loopback 127.0.0.1:10179 -> 127.0.0.1:54078 TCP len 64 [ack,syn]
loopback 127.0.0.1:54078 -> 127.0.0.1:10179 TCP len 52 [ack]
loopback 127.0.0.1:10179 -> 127.0.0.1:54078 TCP len 64 [ack,psh]
hello world
loopback 127.0.0.1:54078 -> 127.0.0.1:10179 TCP len 52 [ack]

Recap

• Binary data handling (Buffers)

• I/O abstraction (Streams)

• Packet snifﬁng (node-pcap)

Node can also do
• HTTP
• Child processes
• Unix domain sockets
• DNS
• UDP
• Crypto
• ...

Speed

var http = require(’http’)
var b = new Buffer(1024*1024);

http.createServer(function (req, res) {
res.writeHead(200);
res.end(b);
}).listen(8000);

by Ryan Dahl

Speed
100 concurrent clients
1 megabyte response

node 822 req/sec
nginx 708
thin 85
mongrel 4

(bigger is better)
by Ryan Dahl

Speed

• NGINX peaked at 4mb of memory

• Node peaked at 60mb

• Very special circumstances
by Ryan Dahl

Danger, Will Robinson

Node makes it trivial to manage
thousands of connections on
multiple protocol levels.

File uploading & processing as a
service for other web applications.

Questions?

✎ @felixge / felix@debuggable.com

Addons

• Add bindings to your favorite C/C++
libraries

• Can be written as a mix of C++ / JavaScript

Addons
#include <v8.h>
#include <node.h>
#include <unistd.h>

using namespace v8;

static Handle<Value> Fork(const Arguments& args) {
HandleScope scope;

pid_t pid = fork();

if (pid < 0)
{
return ThrowException(Exception::Error(String::New("fork: could not fork, pid < 0. see man fork")));
}

if (pid == 0)
{
ev_default_fork();
}

return scope.Close(Number::New(pid));
}

extern "C" void init (Handle<Object> target)
{
HandleScope scope;
NODE_SET_METHOD(target, "fork", Fork);
}

Node.js - As a networking tool

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Editor's Notes