Server side JavaScript: going all the way

Server side JavaScript: going all the way #rejectjs 29.09.11

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Node.js
Ideal use cases
Real time apps, infrastructure duct tape
Badly suited for
CRUD, command line tools, CPU heavy loads
Easy to get started with
Difficult to get into production

Akshell NarwhalJS RingoJS Wakanda GPSEE v8cgi

ServerJS Fragmentation

Sync vs. Async

“ async style is kicking sync style's ass”

sync is “on top of” async – a higher level of abstraction

Sync vs. Async function add(callback) { http.get(url1, function(response1) { var part1 = response1.data; http.get(url2, function(response2) { var part2 = response2.data; callback(part1 + part2); } } }

Sync vs. Async http.get(url1).data + http.get(url2).data

Interoperability
Pure JavaScript modules run anywhere
Templating, parsing, formatting, encoding
Anything doing I/O exposes sync or async API
Defines the interface exposed by higher level packages

CommonJS /1
Assert
Console
System/1.0

CommonJS /2
Binary/B
IO/A
Filesystem/A
JSGI 0.3
HTTP Client /A
Sockets/A
Subprocess

common-node
Implements synchronous CommonJS proposals using node-fibers
Traceur to support latest language features
Bridges the gap between platforms, sync and async

What it's good for?

everything!

What's it actually good for?
Business logic
Lots of state, fine grained error handling
CRUD
Java, Rails, PHP, Python
Command line tools
Cross platform portability

On Threads & Fibers
“ Threads suck”
- Brendan Eich, creator of JavaScript
“ Fibers introduce interleaving hazards — Any function call can cause a yield and then your closure invariants *may be* broken.”
- Kris Kowal, creator of CommonJS/Modules

Concurrency in JavaScript
“ You shouldn’t think that event-based concurrency eliminates synchronization, or shared memory, or anything other than preemption” - Sam Tobin-Hochstadt, member of the Ecma TC39 committee on JavaScript

fibers /1
Co routine implementation using libcoro
Co-operative multitasking
Implicit synchronization

fibers /2
Not a fork or a hack of Node
No wrapper script required
V8 Context and 64KB stack per fiber
Will run on Windows

Node.js process [ closure closure t ->

RingoJS (0.8) process thread stack process thread stack t ->

Common Node (fibers) process fiber stack fiber stack [ t ->

Comparison Node.js Common Node RingoJS Process Count Single Single Multiple State Closure Fiber Stack Thread Stack Multitasking User (co-op) Library (co-op) OS (pre-empt) Memory Usage Low Low High “ Jitter” High High Low

Internals - sleep
exports.sleep = function(milliseconds) {
var fiber = Fiber.current;
setTimeout(function() {
fiber.run();
}, milliseconds);
yield();
} ;

Internals – HttpClient /1
var req = http.request(options, function(r) {
fiber.run(r);
});
req.on('error', function(error) {
fiber.run(error);
});
this.guts.body.forEach(function(block) {
req.write(block.buffer || block);
});
req.end();

Internals – HttpClient /2
var result = yield();
if(result instanceof Error)
throw new Error(result.message);
return {
status: result.statusCode,
headers: result.headers,
body: new Stream(result)
};

Internals - IO
// on 'data', 'end', 'error'
// pause when draining
var listeners = attach(this.stream);
var data = yield();
detach(this.stream, listeners);

Examples

JSGI
exports.app = function(request) {
return {
status: 200,
headers: {},
body: ['Hello World!']
// openRaw(module.filename)
};
};

Spawn & Sleep
spawn(function() {
sleep(10000);
console.log('Hello Server!');
});
return {
status: 200,
headers: {},
body: ['Hello Client!']
};
};

HTTP Proxy
var HttpClient = require('httpclient').HttpClient;
exports.app = function(req) {
req.url = 'http://nodejs.org';
return new HttpClient(req).finish();
};

Twitter Streaming /1
var stream = new TextStream( new HttpClient({
method: 'POST',
url: '...',
headers: {}
body: ['track='+system.args[4]],
timeout: 10000
}).finish().body);

Twitter Streaming /2
var line;
while(true) {
line = stream.readLine();
if(!line.length) break;
if(line.length > 1) {
var message = JSON.parse(line);
console.log(message.text);
}
}

Telnet Chat /1
var socket = require('socket');
var server = new socket.Socket();
var clients = [], client;
server.bind('localhost', 23);

Telnet Chat /2
while(true) {
clients.push(client = server.accept().getStream());
spawn(function() { var stream = client, line;
while((line = stream.read(null)).length) {
clients.forEach(function(c) {
if(stream != c)
c.write(line);
});
}
clients.splice(clients.indexOf(stream), 1);
});
}

Demo
telnet 10.0.0.97

Benchmarks ab -n 50000 -c 50

hello-world
exports.app = function() {
return {
status: 200,
headers: {
'Content-Type': 'text/plain'
},
body: ['Hello World!n']
};
};

string-alloc
for( var i = 1; i <= 50; i++)
b.decodeToString("ascii");
return {
status: 200,
headers: {},
body: [b]
};
};

parse-json
JSON.parse(json);
return {
status: 200,
headers: {},
body: [json]
};
};

static-file
return {
status: 200,
headers: {},
body: openRaw('../README.md')
};
};

set-timeout
sleep(100);
return {
status: 200,
headers: {},
body: []
};
};

Throughput

SyncJS Fragmentation

Road map
common-utils
tests in separate project
narhwal-mongodb fork
hns/stick fork
higher level packages (see project wiki)

Contributing
Google “ common node ”
github.com/olegp/common-node/
npm -g install common-node

Thank you!
@olegpodsechin

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Server side JavaScript: going all the way

by Oleg Podsechin on Sep 24, 2011

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