1. seneca
nodejsdublin
16 August 2012
Richard Rodger
@rjrodger

2. hello
nodejsdublin
• let's start a community project
• how Node.js modules work
• introducing the seneca module

3. getting
started
• how do you learn Node.js?
• how do you contribute to Node.js?
• how do you get a job doing Node.js?

4. your
community
• nodejsdublin is for you
• here to help you learn
• here to build a great community

5. let's start
a project
• less talking, more coding!
• community project with many coders
• something with lots of small pieces

6. seneca
• A Minimal Viable Product toolkit
• let's you build a startup in a weekend :)
• for more about MVPs: http://bit.ly/N25FlZ

7. • Lucius Annaeus Seneca, 4 BC – AD 65
• You have to be stoic to do a startup
• "increases are of sluggish growth, but the way to
ruin is rapid"
* http://cassandralegacy.blogspot.ie/2011/08/seneca-effect-origins-of-collapse.html

8. sign up
• Tweet @nodejsdublin with #seneca
• Mail me: richard.rodger@nearform.com
• Code: github.com/nodejsdublin/seneca

9. node.js
modules
• basic building blocks of Node.js apps
• no special syntax; plain old JavaScript
• no version conflicts!

10. using modules
var _ = require("underscore");
var threes = _.map([1, 2, 3], function(n){ return n*3 });
console.log( threes );
// prints [3, 6, 9]
var mongo = require('mongodb');
var host = 'localhost';
var port = 27017;
var db = new mongo.Db( 'mydatabase',
new mongo.Server(host, port, {}), {});
db.open(function(err, db) { ... }

11. cool
modules
• express - JSP/ASP style dynamic server-side pages
• socket.io - HTML5 real-time web sockets that "just work"
• request - easy outbound calls to web services

12. using npm
• npmjs.org - module repository of record
• usage: npm install modulename
• modules live in local node_modules folder

13. how to pick
a module
• serious modules are on https://github.com/joyent/node/wiki/modules
• popularity! check watchers/issues on github
• documentation, including third party blogs
• ask the community: http://nodejs.org/community/

14. why npm
rocks
• modules are installed separately for each project
• dependencies are also installed separately
• no global conflicts, no cross-dependency
conflicts

15. package.json
• defines a module; lists dependencies
• always create one for each project
• npm install will set up dependencies for you!

16. package.json
{
"name" : "optimist",
"version" : "0.3.4",
"description" : "Light-weight option parsing.",
"main" : "./index.js",
"dependencies" : {
"wordwrap" : ">=0.0.2"
},
"repository" : {
"type" : "git",
"url" : "http://github.com/substack/node-optimist.git"
},
"keywords" : [ "argument", "args", "option", "parser" ]
"author" : { "name" : "James Halliday" },
"engine" : { "node" : ">=0.4 }
}

17. write a
module
• create a project on github
• npm init - creates package.json for you
• start with lib/modulename.js

18. modulename.js
"use strict";
function ModuleName() {
var self = {};
var private = "hidden";
self.member = "data";
self.method = function() { ... };
return self;
}
exports.ModuleName = ModuleName
callingcode.js
var modulename = require('modulename')
var instance = new modulename.ModuleName()

19. parambulator
• written just for this meetup! - sanity checks JSON data structures
• https://github.com/rjrodger/parambulator
• you also need a README.md and LICENSE.txt
• you really should have unit tests; try the vows module

20. file structure
parambulator /
package.json
README.md
LICENSE.txt
lib /
parambulator.js

21. publishing a
module
• the package.json files property is your friend
• register for an account on npmjs.org
• npm publish
• sit back and bask in the glory...

22. seneca
• nearForm builds web/mobile services
• shared set of features every startup needs
• ... must resist ... let's build a framework!

23. shared
features
• user accounts: login/logout, profile pages, social media, ...
• email: transactional, promotional, ...
• e-commerce: gateways, app stores, ...
• admin: data editors, analytics, audit logs, ..

24. seneca is in
production
businesspost.ie chartaca.com stanzr.com

25. command
pattern
• actions are represented by a set of properties
• seneca "executes" them by invoking plugins
• everything that happens is traceable
• business logic is insulated from service providers

26. seneca commands
// register a new user
seneca.act({
on: 'user',
cmd: 'register',
email: 'alice@example.com',
name: 'Alice',
password: '1234',
active: true
},
function(err, result) { ... })
// send an email
seneca.act({
on: 'email',
cmd: 'send',
to: 'alice@example.com',
code: 'thanks-for-registering',
fields: {name:'Alice'}
},
function(err, result) { ... })

27. plugins
• everything is a plugin
• plugins provide actions
• plugins are just modules!

28. seneca plugin
function EchoPlugin() {
var self = {};
self.name = 'echo';
self.init = function(seneca,opts,cb) {
seneca.add({on:'echo'}, function(args,seneca,cb){
var out = args
cb(null,out)
})
cb()
}
self.service = function() {
return function(req,res,next){
if( '/echo' == req.url ) {
res.writeHead(200);
res.end(req.url);
}
else next();
}
}
}
exports.plugin = function() {
return new EchoPlugin()
}

29. shared
data model
• Built-in ODM - Object Document Mapper
• You need this to stay sane
• ActiveRecord-ish API with MongoDB-ish queries

30. seneca data model
var product = seneca.make('product');
product.name = 'Apple';
product.price = 1.99;
product.save$(function(err,savedproduct){
console.log('generated id: '+savedproduct.id);
})
product.load$('1234',function(err,foundproduct){
console.log('found product '+foundproduct);
})
product.list$( {price:1.99}, function(err,list){
for( var i = 0; i < list.length; i++ ) {
console.log( list[i] );
}
})

31. what we
•
have now
messy code that kinda sorta works
• a few hackety hack plugins
• no documentation!

32. what we
need
• plugins! plugins! plugins!
• documentation ( ... just kidding! I'll do that)
• some nodeknockout.com entries -
November 10-12th! Fame & Glory Await!

33. let's code!
• Tweet @nodejsdublin with #seneca
• Mail me: richard.rodger@nearform.com
• Code: github.com/nodejsdublin/seneca