Dcjq node.js presentation

dcjq[5] Node.js: What Is It, How
Does It Work, and What Can I
Use It For Tomorrow?

April 28, 2011
Jonathan Altman
http://async.io/
@async_io

what we’ll cover
• What node is
• Why node is the way it is
• What you can do with it
• Set up a running framework to build web apps
• Dissect a simple node web application

node.js is:
• A non-browser Javascript toolkit/
framework started by Ryan Dahl
• Available for *nix-based systems: Linux, OS X, OpenSolaris (and Windows)

• Built on top of Google’s V8 Javascript engine

• Compatible with many common Javascript libraries out of the box via
CommonJS support (http://www.commonjs.org/)

• A batteries-included framework: HTTP and socket support baked into the
core of the framework

• A framework that is easy to build tooling on top of

• Most importantly: asynchronous from the ground up

node.js is:
• A non-browser Javascript toolkit/framework started by Ryan Dahl

• Available for *nix-based systems: Linux,
OS X, OpenSolaris (and Windows)


• A batteries-included framework: HTTP and socket support baked into the core
of the framework



node.js is:


• Built on top of Google’s V8 Javascript
engine




node.js is:



• Compatible with many common Javascript
libraries out of the box via CommonJS
support (http://www.commonjs.org/)
• A batteries-included framework: HTTP and socket support baked into the core of
the framework



node.js is:



• Compatible with many common Javascript libraries out of the box via CommonJS
support (http://www.commonjs.org/)

• A batteries-included framework: HTTP
and socket support baked into the core
of the framework


node.js is:





• A framework that is easy to build
tooling on top of

node.js is:





• Most importantly: asynchronous
from the ground up

node.js script to determine if
a ﬁle exists

Running it yields:

whoa, back up: asynchronous?
• Core trait of the framework
• Provides scalability
• Long-running operations do not block your server
• Coding looks odd for server writers

whoa, back up: asynchronous?
• Core trait of the framework
• Provides scalability
• Long-running operations do not block
your server
• Coding looks odd for server writers

code looks odd?
• node: • jQuery:
var sys = require('sys'), $('.station_map').live("pagecreate", function() {

path = require('path'),     if(navigator.geolocation) {

fs = require('fs');       navigator.geolocation.getCurrentPosition(function(position){
        initializeMap(position.coords.latitude,position.coords.longit
var fileName = process.ARGV[2]; ude);
path.exists(fileName, function(exists) {       });

if (!exists) {     }

sys.puts(fileName + ' not found');   });

return; // snippet taken from https://github.com/mikeymckay/Capital-

} Bikeshare/blob/master/capitalbikeshare.js

sys.puts('w00t! ' + fileName + ' exists!');
});
// https://github.com/jonathana/dcjq_5_nodejs/blob/master/
node_async_example.js

Doesn’t the code look just like the event-driven javascript DHTML-
based web apps have been written in for years?

node: up and running
• node.js and its ecosystem still
evolves very fast
• Highly recommended to not put any of it in your
system paths
• We’ll use ~/local (lots of examples do so...)

• node.js and its ecosystem still evolves very fast
• Highly recommended to not put
any of it in your system paths
• We’ll use ~/local (lots of examples do so...)

• node.js and its ecosystem still evolves very fast
• Highly recommended to not put any of it in your
system paths

• We’ll use ~/local (lots of
examples do so...)

be careful for:
• Highly recommended not to
install node in “system”
locations yet
• Uncertain security/threat model
• Hide behind a reverse proxy

be careful for:
• Highly recommended not to install node in
“system” locations yet


be careful for:


be careful for:
• Everything in this presentation
could be wrong by now!

basic components
• node.js itself
• nave: manages multiple versions of node
• npm: node package manager. Like ruby’s gem or
python’s easy_install

basic components
• node.js itself

• nave: manages multiple versions
of node
• npm: node package manager. Like ruby’s gem or
python’s easy_install

basic components
• node.js itself
• nave: manages multiple versions of node
• npm: node package manager.
Like ruby’s gem or python’s
easy_install

managing versions-nave
• Again, node.js and its libraries
move fast
• Like python’s virtualenv or ruby’s rvm, there are
nave and nvm for node
• Let’s use nave
• Allows us to have a “stable” environment
• Allows us to test newer versions without risking
“stable”

• Again, node.js and its libraries move fast

• Like python’s virtualenv or
ruby’s rvm, there are nave and
nvm for node


“stable”


• Allows us to have a “stable”
environment
“stable”


• Allows us to test newer
versions without risking “stable”

install node.js via nave
• node.js must be built from
source
• nave handles this for you. Examples:
nave use stable
nave use latest
nave use 0.4.6

• nave downloads, builds, and installs the node version
you asked for!

• node.js must be built from source

• nave handles this for you.
Examples:
nave use stable
nave use latest
nave use 0.4.6

• nave downloads, builds, and installs the node version
you asked for!

• node.js must be built from source
• nave handles this for you. Examples:
nave use stable
nave use latest
nave use 0.4.6

• nave downloads, builds, and installs
the node version you asked for!

installing nave
• Adapted from https://gist.github.com/
579814#ﬁle_use_nave.sh
mkdir ~/.nave
pushd ~/.nave
wget http://github.com/isaacs/nave/raw/master/
nave.sh
ln -s $PWD/nave.sh ~/local/bin/nave

nave installing a version...

Several thousand lines of build output deleted...

npm: node package manager
• Handles easy installation of node
packages
• Databases: mysql, postgresql, sqlite, mongodb, etc
• DOM: jsdom
• web frameworks: e.g. express, connect, spark/spark2
• DOM manipulation: YUI3, jQuery
• Utility libraries: backbone/spine, underscore, socket.io
• Templating: mustache, handlebars, ejs, etc
• Testing: vows, expresso, nodemock, nodeunit

npm: node package manager
• Handles easy installation of node packages
• Databases: mysql, postgresql, sqlite, mongodb, etc
• DOM: jsdom
• web frameworks: e.g. express, connect, spark/spark2
• DOM manipulation:YUI3, jQuery
• Utility libraries: backbone/spine, underscore,
socket.io
• Templating: mustache, handlebars, ejs, etc
• Testing: vows, expresso, nodemock, nodeunit

install npm
curl http://npmjs.org/install.sh | sh

That’s it, there is no step 2!

it’s alive
jonathan@ubuntu:~$ node --version
v0.4.7
jonathan@ubuntu:~$ npm --version
1.0.3
jonathan@ubuntu:~$

let’s write a web app
var sys = require('sys'),
http = require('http');

http.createServer(function(req, res) {
res.writeHead(200, {'Content-Type': 'text/html'});
res.write('<h1>Hello World</h1>');
res.end();
}).listen(8000);

sys.puts('Server running at http://127.0.0.1:8000/');
//https://github.com/jonathana/dcjq_5_nodejs/blob/master/helloworld.js

let’s run the web app
jonathan@ubuntu:~/src/dcjq_5_nodejs$ nave use stable
Already installed: 0.4.7
using 0.4.7
jonathan@ubuntu:~/src/dcjq_5_nodejs$ PATH=$PATH:`npm
bin`
jonathan@ubuntu:~/src/dcjq_5_nodejs$ node
helloworld.js
Server running at http://0.0.0.0:8000/

• That PATH= command is for npm-installed executables

now let’s debug the web app
• node-inspector is an npm package for debugging node over http!
jonathan@ubuntu:~/src/dcjq_5_nodejs$ node-inspector &
[1] 6274
visit http://0.0.0.0:8080/debug?port=5858 to start debugging
jonathan@ubuntu:~/src/dcjq_5_nodejs$ node --debug
helloworld.js
debugger listening on port 5858
Server running at http://0.0.0.0:8000/

• The webkit javascript debugging engine works really well with this.
Debugging in Chrome FTW!

and see us stop at a breakpoint!

advantages of node
• Javascript makes callback-based
(“event”) programming familiar
• Fast: framework says take operations that normally block
webserver and make them asynchronous
• Same language on client and server
• Same libraries on client and server
• Long-running connections to lots of clients: Comet

advantages of node
• Javascript makes callback-based (“event”) programming familiar
• Fast: framework says take operations
that normally block webserver and
make them asynchronous

advantages of node


advantages of node

• Long-running connections to lots of
clients: Comet

installing node packages

Some more output deleted...

sample web development stack
• node-inspector: debugging
• express (and connect): web framework, middleware, routing, controllers
• spark2: nice front-end for controlling node servers
• ejs templates: embedded javascript, for views
• connect-mongodb: mongoDB-backed sessions
• mongoose: mongoDB-based object mapper for models
• test: yeah, you should pick some packages and use them
• jsdom: manipulate html DOMs server-side
• jquery and/or YUI3: do cool stuff server side with the DOM

Examples/Sample App
• See https://github.com/jonathana/dcjq_5_nodejs for the
example code used in this presentation and a heavily-
commented simple web app built using many of the
packages on the previous slides

appendix: Resources
• Ryan Dahl: (http://tinyclouds.org/, https://github.com/ry)
• Ryan’s jsconf 2009 presentation: http://s3.amazonaws.com/four.livejournal/
20091117/jsconf.pdf
• Simon Willison’s blog post re: node.js: http://simonwillison.net/2009/Nov/23/node/
• node.js home: http://nodejs.org/, git repo: https://github.com/joyent/node/

• node modules: https://github.com/joyent/node/wiki/modules
• Isaac Schlueter: (npm and nave) https://github.com/isaacs/, http://blog.izs.me/
• Dav Glass’ mind-bending demonstration of using YUI server-side: http://
developer.yahoo.com/yui/theater/video.php?v=glass-node
• Nice list of some apps built using node.js + express: http://expressjs.com/
applications.html

Dcjq node.js presentation

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