All I Need to Know I Learned by Writing My Own Web Framework

All I Really Need to Know* I Learned by Writing My Own Web Framework Ben Scofield 7 November 2008 Rubyconf * about Ruby and the web

DSLs DSL Intimidate and Frighten ﬂickr: cwsteeds

Rails your custom framework

Starter Projects

Hello World

main() { printf(quot;hello, worldnquot;); } -module(hello). -export([hello/0]). hello() -> io:format(quot;Hello World!~nquot;, []). PROGRAM HELLO PRINT*, 'Hello World!' END

main = putStrLn quot;Hello Worldquot; Imports System.Console Class HelloWorld Public Shared Sub Main() WriteLine(quot;Hello, world!quot;) End Sub End Class !greeting. +!greeting : true <- .print(quot;Hello Worldquot;).

Applications

To-do lists

DIY Blog

Frameworks?

PHP Framework (based on Rails)

NOT FOR PRODUCTION!

well, maybe for production

but really: NOT FOR PRODUCTION!

Frameworks

ActionMailer ActionPack ActiveRecord Ruby on Rails ActiveResource ActiveSupport Railties

request => response

Sequel ActiveRecord persistence layer DataMapper Og

ERB Liquid Amrita2 templating layer Erubis Markaby HAML

Ramaze Waves ActionPack the middle layer Merb Core Sinatra Camping

ActionMailer Merb Helpers utilities ActiveSupport Railties

Mack CGI Coset SCGI Camping LSWS Halcyon Mongrel Maveric WEBrick Sinatra FastCGI Vintage Fuzed Ramaze Thin Waves Ebb Merb

mod_rack

Rack::Lint Rack::URLMap Rack::Deflater Rack::CommonLogger middlewares Rack::ShowExceptions Rack::Reloader Rack::Static Rack::Cache

Rack::Request utility Rack::Response

Other Layers

Sequel ActiveRecord persistence layer DataMapper Og

ERB Liquid Amrita2 templating layer Erubis Markaby HAML

Start at the End

Vision

REST and Resources

fully-formed web applications built on resources

Birth of Athena

Dionysus ask me after if you don’t get the joke

Project

Extraction ﬂickr: 95579828@N00

class Habit < Athena::Resource def get @habit = Habit.find(@id) end # ... end RouteMap = { :get => { //habit/new/ => {:resource => :habit, :template => :new}, //habit/(d+)/ => {:resource => :habit}, //habit/(d+)/edit/ => {:resource => :habit, :template => :edit} }, :put => { //habit/(d+)/ => {:resource => :habit} }, :delete => { //habit/(d+)/ => {:resource => :habit} }, :post => { //habit// => {:resource => :habit} } }

Results

puts quot;Starting Athena applicationquot; require 'active_record' require File.expand_path(File.join('./vendor/athena/lib/athena')) puts quot;... Framework loadedquot; Athena.require_all_libs_relative_to('resources') puts quot;... Resources loadedquot; use Rack::Static, :urls => ['/images', '/stylesheets'], :root => 'public' run Athena::Application.new puts quot;... Application startednnquot; puts quot;^C to stop the applicationquot;

module Athena class Application def self.root File.join(File.dirname(__FILE__), '..', '..', '..', '..') end def self.route_map @route_map ||= { :get => {}, :post => {}, :put => {}, :delete => {} } @route_map end def call(environment) request = Rack::Request.new(environment) request_method = request.params['_method'] ? # ... matching_route = Athena::Application.route_map # ... if matching_route resource = matching_route.last[:class].new(request, request_method) resource.template = matching_route.last[:template] return resource.output else raise Athena::BadRequest end end end end

module Athena class Resource extend Athena::Persistence attr_accessor :template def self.inherited(f) unless f == Athena::SingletonResource url_name = f.name.downcase routing = url_name + id_pattern url_pattern = /^/#{routing}$/ Athena::Application.route_map[:get][/^/#{routing}/edit$/] = # ... Athena::Application.route_map[:post][/^/#{url_name}$/] = # ... # ... end end def self.default_resource Athena::Application.route_map[:get][/^/$/] = {:class => # ... end def self.id_pattern '/(d+)' end def get; raise Athena::MethodNotAllowed; end def put; raise Athena::MethodNotAllowed; end def post; raise Athena::MethodNotAllowed; end def delete; raise Athena::MethodNotAllowed; end # ... end end

class Habit < Athena::Resource persist(ActiveRecord::Base) do validates_presence_of :name end def get @habit = Habit.find_by_id(@id) || Habit.new_record end def post @habit = Habit.new_record(@params['habit']) @habit.save! end def put @habit = Habit.find(@id) @habit.update_attributes!(@params['habit']) end def delete Habit.find(@id).destroy end end

class Habits < Athena::SingletonResource default_resource def get @habits = Habit.all end def post @results = @params['habits'].map do |hash| Habit.new_record(hash).save end end def put @results = @params['habits'].map do |id, hash| Habit.find(id).update_attributes(hash) end end def delete Habit.find(:all, :conditions => ['id IN (?)', @params['habit_ids']] ).map(&:destroy) end end

module Athena module Persistence def self.included(base) base.class_eval do @@persistence_class = nil end end def persist(klass, &block) pklass = Class.new(klass) pklass.class_eval(&block) pklass.class_eval quot;set_table_name '#{self.name}'.tableizequot; eval quot;Persistent#{self.name} = pklassquot; @@persistence_class = pklass @@persistence_class.establish_connection( YAML::load(IO.read(File.join(Athena::Application.root, # ... ) end def new_record(*args) self.persistence_class.new(*args) end def persistence_class @@persistence_class end # ...

Lessons About the Web

HTTP status codes http://thoughtpad.net/alan-dean/http-headers-status.gif

207 Multi-Status

207 sucks Multi-Status

rack::cache http://tomayko.com/src/rack-cache/

Lessons About Ruby

module Athena class Application # ... def process_params(params) nested_pattern = /^(.+?)[(.*])/ processed = {} params.each do |k, v| if k =~ nested_pattern scanned = k.scan(nested_pattern).flatten first = scanned.first last = scanned.last.sub(/]/, '') if last == '' processed[first] ||= [] processed[first] << v else processed[first] ||= {} processed[first][last] = v processed[first] = process_params(processed[first]) end else processed[k] = v end end processed.delete('_method') processed end # ... end Form Parameters end

module Athena module Persistence def self.included(base) base.class_eval do @@persistence_class = nil end end def persist(klass, &block) pklass = Class.new(klass) pklass.class_eval(&block) pklass.class_eval quot;set_table_name '#{self.name}'.tableizequot; eval quot;Persistent#{self.name} = pklassquot; @@persistence_class = pklass @@persistence_class.establish_connection( YAML::load(IO.read(File.join(Athena::Application.root, # ... ) end def new_record(*args) self.persistence_class.new(*args) end def persistence_class @@persistence_class end # ... Dynamic class creation

Tangled classes ﬂickr: randomurl

module Athena module Persistence # ... def method_missing(name, *args) return self.persistence_class.send(name, *args) rescue ActiveRecord::ActiveRecordError => e raise e rescue super end end end Exception Propagation

this session has been a LIE

More to learn ﬂickr: glynnis

... always ﬂickr: mointrigue

http://github.com/bscofield/athena (under construction)

Thank you! Questions? Ben Scofield Development Director, Viget Labs http://www.viget.com/extend | http://www.culann.com ben.scofield@viget.com | bscofield@gmail.com

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All I Need to Know I Learned by Writing My Own Web Framework

by Ben Scofield on Nov 07, 2008

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