When to tell your kids about presentation caching Matthew Deiters - PowerPoint PPT Presentation

When to tell your kids about presentation caching Matthew Deiters www.theAgileDeveloper.com

A practical guide to stuffing your app’s bits into someone else’s browser

Questions: @mdeiters

Rapid Feature Development

Rapid Feature Adoption & Development Growth

Client Caching

client.is_a?(Browser) == true

Browsers & Leveraging HTTP 1.1

Fewer Requests Smaller Responses

80/20 Rule (Pareto Principle)

80% of the wealth owned by 20% of people

80% of your time is with 20% of your acquaintances

80% of the time you wear 20% of your clothing

80% of a request is spent on the wire

Today

Reducing Network Tra � c Last-Modified Header ETag Header GZip Today Minification max-age Header Cookies Expires Header

ME

To illustrate: Scalability

Applicable for?

Applicable for? Enterprises

Applicable for? Enterprises High Traffic Web Sites

Applicable for? Enterprises High Traffic Web Sites Startups

Enterprise

High Traffic Sites

Reduce network traffic Reduce response times Reduce load

Facebook: Bumpersticker

1.4 Million Average Users

1.4 Million Average Users Average 20 page views

“Push everything you possibly can to the client to reduce the amount of traffic going over the network...”

Startups

HTTP 1.1 Enity Tags

www.nextdaypets.com

\puppies\43

HTTP/1.x 200 OK Etag: "8b2242293d5e5b02e99b3be73fc0c9fa"

www.nextdaypets.com

\puppies\43 If-None-Match: "8b2242293d5e5b02e99b3be73fc0c9fa"

HTTP/1.x 304 Not Modified

Last-Modified: Tue, 12 Dec 2006 03:03:59 GMT ETag: "10c24bc-4ab-457e1c1f"

Last-Modified: Tue, 12 Dec 2006 03:03:59 GMT ETag: "10c24bc-4ab-457e1c1f" If-Modified-Since: Tue, 12 Dec 2006 03:03:59 GMT If-None-Match: "10c24bc-4ab-457e1c1f"

+ Conditional Get

class PeopleController < ApplicationController def show @person = Person.find(params[:id]) respond_to do |wants| #... end end end

#response.rb def last_modified=(utc_time) def etag=(etag)

#request.rb def fresh?(response) def not_modified?(modified_at) def etag_matches?(etag)

class PeopleController < ApplicationController def show @person = Person.find(params[:id]) respond_to do |wants| #... end end end

class PeopleController < ApplicationController def show @person = Person.find(params[:id]) response.last_modified = @person.updated_at.utc respond_to do |wants| #... end end end

class PeopleController < ApplicationController def show @person = Person.find(params[:id]) response.last_modified = @person.updated_at.utc response.etag = @person respond_to do |wants| #... end end end

class PeopleController < ApplicationController def show @person = Person.find(params[:id]) response.last_modified = @person.updated_at.utc response.etag = @person return head(:not_modified) if request.fresh?(response) respond_to do |wants| #... end end end

response.etag = @person # => “5cb44721b6ce18857ff6900486dc4aba” @person.cache_key # => "people/5-20071224150000"

def fresh_when(options) def stale?(options)

class PeopleController < ApplicationController def show @person = Person.find(params[:id]) response.last_modified = @person.updated_at.utc response.etag = @person return head(:not_modified) if request.fresh?(response) respond_to do |wants| #... end end end

class PeopleController < ApplicationController def show @person = Person.find(params[:id]) if stale?(:etag => @person, :last_modified => @person.updated_at.utc) respond_to do |wants| #... end end end end

Last-Modified vs ETag

Later response.etag = [@admin, @person, flash]

def handle_conditional_get! if nonempty_ok_response? self.etag ||= body if request && request.etag_matches?(etag) self.status = '304 Not Modified' self.body = '' end end set_conditional_cache_control! if etag? || last_modified? end

SInce Feb 2007 self.etag ||= body

http://localhost:3000/people GET /people HTTP/1.1

http://localhost:3000/people GET /people HTTP/1.1 HTTP/1.x 200 OK ... Etag: "94785662c6f60cb96681ed1b09a44783"

http://localhost:3000/people GET /people HTTP/1.1 HTTP/1.x 200 OK ... Etag: "94785662c6f60cb96681ed1b09a44783" http://localhost:3000/people GET /people HTTP/1.1 If-None-Match: "94785662c6f60cb96681ed1b09a44783"

http://localhost:3000/people GET /people HTTP/1.1 HTTP/1.x 200 OK ... Etag: "94785662c6f60cb96681ed1b09a44783" http://localhost:3000/people GET /people HTTP/1.1 If-None-Match: "94785662c6f60cb96681ed1b09a44783" HTTP/1.x 304 Not Modified Etag: "94785662c6f60cb96681ed1b09a44783"

send_file

Assets

Assets

Assets

INODE

/intl/en_ALL/images/logo.gif ETag: "48b6a5bf-47f4-a0757"

/intl/en_ALL/images/logo.gif /intl/en_ALL/images/logo.gif ETag: "48b6a5bf-47f4-a0757" ETag: "48b6a5bf-61a-21c86a4"

/intl/en_ALL/images/logo.gif /intl/en_ALL/images/logo.gif ETag: "48b6a5bf-47f4-a0757" ETag: "48b6a5bf-61a-21c86a4"

Avoid Cache Expiration & Validation

/stylesheets/screen.css?1219926880 CACHE BUSTER!

Now <FilesMatch "\.(pdf|flv|jpg|jpeg|png|gif|js|css|swf)$"> Header set Cache-Control "public" ExpiresActive On ExpiresDefault “access plus 10 years” FileETag None Header unset Last-Modified Header unset ETag </FilesMatch>

Server 1 Server 2 /images/beach.png?12414775 47 /images/beach.png?12414775 54

Option 1 #config/environments/production.rb #Subversion ENV['RAILS_ASSET_ID'] = YAML::load(`svn info $RAILS_ROOT`)["Revision"].to_i #GIT (Check out Grit too) ENV['RAILS_ASSET_ID'] = File.read(RAILS_ROOT + '/.git/refs/heads/deploy').chomp

Option 2 task :finalize_update, :except => { :no_release => true } do stamp = Time.now.utc.strftime("%Y%m%d%H%M.%S") asset_paths = %w(images stylesheets javascripts).map do |asset| "#{latest_release}/public/#{p}" end.join(" ") run "find #{asset_paths} -exec touch -t #{stamp} {} ';'; true", :env => { "TZ" => "UTC" } end

Option 2 #Capistrano 2.4 set :normalize_asset_timestamps, true

Option 3

Option 3 use-commit-times

Now ActionView::Helpers::AssetTagHelper.cache_asset_timestamps = true

Proxies & Via Header