Node.js Explained

Rising from non-existence a few short years ago, Node.js is already attracting the accolades and disdain enjoyed and endured by the Ruby and Rails community just a short time ago. It overtook Rails as the most popular Github repository in 2011 and was selected by InfoWorld for the Technology of the Year Award in 2012. This presentation explains the basic theory and programming model central to Node's approach and will help you understand the resulting benefits and challenges it presents. You can also watch this presentation at http://bit.ly/1362UGA

Transcript

1. explained Jeff Kunkle March 2, 2012
2. Node.js is a platform built on Chrome’s JavaScript runtime for easily building fast, scalable network applications. Node.js uses an event driven, non-blocking I/O model that makes it lightweight and efficient, perfect for data-intensive real-time applications that run across distributed devices. DOWNLOAD DOCS v0.6.11
3. Theory Benefits Challenges 1 2 3
4. Theory
5. I/O Latency L1 3 cycles L2 14 cycles RAM 250 cycles Disk 41,000,000 Network 240,000,000 Source: Ryan Dahl’s 2008.11.08 node.js presentation
6. 0 75,000,000 150,000,000 225,000,000 300,000,000 L1 L2 RAM Disk Network 240,000,000 41,000,000 250 14 3 CPU Cycles
7. I/O Latency L2 RAM Disk Network L1 5 83 13,666,666 80,000,000 L2 18 2,928,571 17,142,857 RAM 164,000 960,000 Disk 6
8. Waiting... route request query db or web service process results format response write to log file
9. Scaling with Threads thread 1 thread 2 thread 3 thread 4 Context switching overhead Execution stacks take up memory Complicates concurrency Handles up to 4 concurrent requests
10. Scaling with Processes process 1 process 2 process 3 process 4 High memory usage Handles up to 4 concurrent requests Process scheduling overhead
11. Scaling with an Event Loop process 1 network filesystem Thread Pool and Async I/O APIs Handles many concurrent requests in one process/thread
12. Event Loop filesystem network process other Event Queue Thread Pool Event Loop
13. Platform node standard library node bindings (http, socket, file system) V8 thread pool (libeio) event loop (libev) DNS (c-ares) crypto (OpenSSL)
14. Examples setTimeout(function () { console.log('This will still run.'); }, 500);
15. HTTP Server var http = require('http'); http.createServer(function (request, response) { response.writeHead(200, {'Content-Type': 'text/plain'}); response.end('Hello World\n'); }).listen(8124); console.log('Server running at http://127.0.0.1:8124/');
16. Serve a Static File var http = require('http'); http.createServer(function (request, response) { fs.readFile('/etc/passwd', function (err, data) { if (err) { response.writeHead(500, err.message); response.end(); } else { response.writeHead(200, {'Content-Type': 'text/plain'}); response.end(data); } }); }).listen(8124);
17. Read a File in Chunks var fs = require('fs'); var stream = fs.createReadStream('huge.txt'); stream.on('data', function (data) { console.log(data); }); stream.on('end', function () { console.log('done'); }); stream.on('error', function (err) { console.log(err); });
18. Challenges
19. Asynchronous I/O var fs = require('fs'); fs.stat('/etc/passwd', function (err, stats) { if (err) return; if (stats.isFile()) { fs.readFile('/etc/passwd', function (err, data) { if (err) throw err; console.log(data); }); } });
20. Debugging
21. CPU-intensive Tasks 1thread be careful!
22. Rapidly Changing v0.6.11 2012.02.17 v0.7.5 2012.02.23 v0.7.4 2012.02.14 v0.7.3 2012.02.07 v0.7.2 2012.02.01 v0.7.1 2012.01.23 v0.7.0 2012.01.16 v0.6.10 2012.02.02 v0.6.9 2012.01.27 v0.6.8 2012.01.19 v0.6.7 2012.01.06 v0.6.12 2012.03.02
23. Benefits
24. Multi-platform
25. Lightweight Single thread
26. Dead-lock Free Single thread simplifies concurrency
27. Monoglot Programming JavaScript on the client JavaScript on the server
28. Popular
29. Fast Ruby 1.9 used what fraction? times more? Ruby 1.9 used what fraction? times more? Ruby 1.9 used what fraction? times more? Ruby 1.9 used what fraction? times more? Benchmark Time Memory Code pidigits 1 /16 1/ 2 1/ 3 reverse-complement 1/ 2 1/ 2 1/ 2 k-nucleotide 2× 1/ 2 ± binary-trees 6× 1/ 2 ± fasta 7× 6× ± regex-dna 9× 2× ± n-body 16× 1/ 4 ± spectral-norm 19× 1/ 2 ± fannkuch-redux 51× ± ± Source: http://shootout.alioth.debian.org/u32/benchmark.php
30. Lua
31. Perl
32. PHP
33. Python 3
34. JRuby
35. Clojure
36. Java
37. C
38. Vibrant Community 7,661 packages as of 3:00pm EDT 2012.03.02
39. Conceptually Simple filesystem network process other Event Queue Thread Pool Event Loop
40. Small Core 36 JavaScript source files 36 C++ source files as of March 1, 2012 at 10:50pm on v0.6 branch
41. Short Learning Curve Understand JavaScript Understand Event-based Programming You just need to learn new APIs Understand Node.js Theory
42. Getting Smart
43. 1 install Node from source 2 write some small programs 3 read the source 4 re-implement a popular pkg
44. Check out some Packages express web framework persist ORM framework db-migrate database migrations async async helpers socket.io realtime networking dnode RPC vows BDD framework java bridge to Java API