outline.txt

Introduction to Node.js
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What is Node.js?
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- Since 2009, pretty young project.
- Built on top of V8, Google's JavaScript runtime.
- Environment, not a server or a set of servers, not a framework.
- Provides low-level I/O related libraries
- Asynchronous and evented (adds an event loop on top of JavaScript in particular)


Origins
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- Most server apps use I/O a lot:
 * to retrieve a file
 * to exchange with a database
 * to send requests to a remote peer
- Performance issues with usual server implementations in synchronous environment:
 * costly to maintain, create, delete threads in most environments
 * need to create as many threads as pending requests


Why JavaScript?
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- It's in all Web browsers, more available than Java in its glory days.
- Good to use same language for client code and server code, possibility to reuse most of the code
- JSON is popular: JSON.parse and JSON.stringify for direct use in JavaScript
- Trendy, growing community, growing number of libraries, open source friendly (people used to copy-and-paste in the browser)


Installing Node.js
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- Note on versioning.


The Event loop
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- Basis for asynchronous programming
- All usual JavaScript devs know what it is because that's how a Web browser works.
- Note setTimeout is window.setTimeout, i.e. setTimeout is not a JavaScript feature.
- Rule of thumb of async:
 * use a callback for one-off events at the end of a process
 * use events for repeating events or in-progress
- Async is hard. It's easy to create deeply-nested spaghetti code. It's also easy to lose track of what is synchronous and what is not (e.g. Underscore functions are synchronous yet use callbacks).
- One timeline.
- Notion of "tick".
- Synchronous has its merits. It's actually possible within a Web browser in a Web worker without blocking the main thread. Short discussion on CommonJS.
- Asynchronous programming techniques:
 * define processing bits before, assigning names to each of them
 * document code ;)


Node.js basics
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- No "window" object. Node.js is not a Web browser!
- No DOM or jQuery. Node.js is not a Web browser!
- A few global objects replace "window" in Node.js, in particular:
 * process
 * usual "window" thingies such as console, setTimeout, clearTimeout
 * require, exports, module.exports for module management
- Callbacks with error as first argument.
- Events: EventEmitter class
- Node runs on the command-line. You can use it for batch files!


Scoping context
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- Beware of scope. The usual construct:
  (function () { ... })()
  useful to merge code.
- Private functions/properties are scoped functions/properties
- "this" is Charlie in JavaScript. ask yourself the question: where is Charlie?
  $('a').click(function () {
    // "this" is the DOM element that triggered
  });
- Ways to change "this":
 * func.call(context) or func.apply(context)
 * _.bind(func, this);
 * var charlie = this;


Node modules
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- Core modules that expose low-level functionality (Crypto, DNS, File System, TCP, HTTP, VM)
- "Userland" modules that turn Node.js into an environment that is pleasant to work with at a higher level
- Most userland modules can be installed with "npm".
- Recommended modules: underscore.js, async.js
- Presentation of "npm"
- package.json
- "require", "exports" and "module.exports" functions.


Debugging in Node.js
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- node-inspector: https://github.com/dannycoates/node-inspector
- "debugger;" statements for breakpoints
- node debug for command-line gurus

Creating a simple HTTP server
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var http = require('http');
var server = http.createServer(function (request, response) {
  response.writeHead(200, {
    'content-type': 'text/plain'
  });
  response.end('These dotJS workshops rulez!');
});
server.listen(8000);
- Exercise: ???


Working with streams
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- 'data', 'end', 'close' events
- Exercise: chat application?


Web server made easy with express.js
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- routes
- middlewares
- templating
- Exercise: ???


Connecting to a MongoDB instance
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- mongoDB installation: http://www.mongodb.org/
- In Node.js, using MongoDB native API module:
  npm install mongodb
- Using Mongoose
- Schema definition
- Beware, getters/setters used all around!


Putting it all together
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- Create Twitter, connecting to a MongoDB instance.
- Create a Web application connected to a MongoDB instance that stores contact information.
- Client-side, the Web application renders the list of contacts it has already saved and lets a user upload its own contact information.
- The app should refresh the list almost in real-time.


Deploying your app on Heroku
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- Create account
- Heroku Toolbelt: https://toolbelt.herokuapp.com/
- A "simple" git push command
- Creating Heroku remote commands


Going further (if time allows and interest shows up)
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- Unification of client and server codebase:
 * asynchronous modules using AMD
 * Backbone.js as common foundation for models?