Node.js is a JavaScript runtime built for building scalable network applications. It uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, particularly for real-time web applications with many concurrent connections. The presentation covered server models like multi-threaded and single-threaded approaches, how Node.js implements non-blocking asynchronous I/O, its event loop programming model, and demonstrated a simple Node.js web server.

1. node.jsbuilding for high performance & high concurrency Nam Ho KMS Technology

2. About me ALT.NET Saigon (a .NET user group) Twitter - @hotrannam #altnetsg

3. Agenda Server models Non-Blocking I/O Programming model Demo

4. Multi-Threaded server Request A thread is created in response to the request

5. Multi-Threaded server Spawning threads to handle concurrent requests

6. Multi-Threaded server Long running operations cause threads to block. Subsequent requests are in queue.

7. Multi-Threaded server Disadvantages Thread context switching is slow Threads take up too much memory Thread-per-connection does not scale

8. Blocking I/O Synchronous I/O Wait for I/O operations to complete Idle time var post = db.query(“select * from posts where id = 1”); // waiting, waiting, waiting showPost(post); // do something unrelated to post doAnotherThing();

9. Non-Blocking I/O Asynchronous I/O Continue processing Improve throughputand latency var post = db.query(“select * from posts where id = 1”, callback); doAnotherThing(); callback = function(post){ showPost(post); }

10. Single-Threaded server Endless event-loop fires off long running operations and then moves to next request

11. Multi-Threaded vs. Single-Threaded http://blog.webfaction.com/a-little-holiday-present

12. Multi-Threaded vs. Single-Threaded http://blog.webfaction.com/a-little-holiday-present

13. What is Node Created by Ryan Dahl Google’s V8 JavaScript engine Event loop Non-blocking I/O Event binding

14. Where does Node fit Node is ideal for apps which have tens of thousands of concurrent connections.

15. Why JavaScript First class function Closure V8 is fast

16. A simple web server var http = require("http"); http.createServer(function(req, res){ res.writeHead(200, {"Content-Type": "text/plain"}); return res.end("Hello Barcamp Saigon"); }).listen(8080); console.log("Server running at port 8080");

17. Callback var http = require("http"); var callback = function(req, res){ res.writeHead(200, {"Content-Type": "text/plain"}); return res.end("Hello Barcamp Saigon"); } http.createServer(callback).listen(8080); console.log("Server running at port 8080");

18. Event binding var fs = require(“fs"); var readStream = fs.createReadStream(“/etc/sources”); readStream.addListener(“data”, function(data){ console.log(data); }); readStream.addListener(“end”, function(data){ console.log(“file ended”); });

19. Parallel vs. Serial var fs = require("fs"); function writeBarcamp(){ return fs.writeFile('./barcamp.txt', 'Hi Barcamp!', function writeFile(err){ fs.readFile('./barcamp.txt', 'UTF-8', readFile); }); } function writeNode(){ return fs.writeFile('./node.txt', 'Hi Node!', function writeFile(err){ fs.readFile('./node.txt', 'UTF-8', readFile); }); } function readFile(err){} writeBarcamp(); writeNode();

20. Demo

21. Thanks you! @hotrannam