Very basic Node.js introduction

1. Node.js quick intro

2. Node.js
Platform for scalable network applications
servers and clients
Uses event driven, non-blocking I/O
epoll, kqueue, /dev/poll, or select
process never blocks, no deadlocks
internal event loop

3. Event driven platform
Non-blocking - not waiting for things to finish
Uses asynchronous platform-specific API’s
“Single-threaded” - sequential task execution
Runs synchronous API’s in threads

4. Node.js architecture
Based on V8
JavaScript Virtual
Machine (engine)
+ standard library
Google Chrome uses
V8 too

5. Event loop illustration
// event loop
while (true) {
lock (queue) {
var tickEvents = copy(queue);
queue.empty();
}
for (var i = 0; i < tickEvents.length; i++) {
InvokeJSFunction(tickEvents[i]);
}
}
// thread-safe event pushing
lock (queue) {
queue.push(event);
}
// io call
fs.readFile(“pwd”, function(e, d){
console.log(“file data:”, d);
});

6. Callbacks
var fs = require(“fs”);
var cb = function(err, data){
if (err) throw err;
console.log(“File contents: ” + data);
}
fs.readFile(“pwd1”, cb);
fs.readFile(“pwd2”, cb);

7. Http server app
var http = require('http');
http.createServer(function (req, res) {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.end('Hello Worldn');
}).listen(1337, "127.0.0.1");

8. Node.js launching
$ echo ‘console.log(“hey there”)’ | node
$ node app.js

9. Workers event loop

10. That was quick Node.js introduction
Thanks