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)• 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

so what does code look like?

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

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.longitvar 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...)

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• Uncertain security/threat model• Hide behind a reverse proxy• 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

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”

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

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”

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!

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 npmcurl http://npmjs.org/install.sh | sh That’s it, there is no step 2!

it’s alivejonathan@ubuntu:~$ node --versionv0.4.7jonathan@ubuntu:~$ npm --version1.0.3jonathan@ubuntu:~$

installing node packages Some more output deleted...

let’s write a web appvar 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

and visit our webpage

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

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

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Dcjq node.js presentation

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