How To Automate Optimization and Deployment Of Static Content

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A lot of traffic between users and your site comes from the static content you’re using to set up the user interface, namely layout graphics, Stylesheets and Javascript files.

This article shows a method to improve the providing of static content for a web platform. Further, it will show you a way to automate the deployment of these files, so you can deliver them with least effort but with maximum performance.

This tutorial will take some time to set it up, but it’s going to save you hours of work in the future and will improve your page speed significantly.

1. Why do I need this?

There are several approaches to optimize the delivery of contents.
Some use on-the-fly compression via the server itself or a scripting language, which costs performance and does not optimize the structure and content of the files.

The method shown here prepares the files once and also merges and optimizes the code of CSS and Javascript files before the files are compressed, which makes the delivery of them even faster.

  • Most browsers download only two files from a source at once1. If a page needs to load more files from one domain, they get queued.
  • More files to transfer mean more requests to the server, more traffic and more usage of the server’s performance. For the users of the platform, this means longer loading times.
  • The more steps you need to deploy these files, the more space for mistakes is given.
  • Deployment is boring. It’s far more exciting to invest some time once, to set up a reusable automation, than wasting time doing the same copy/paste/upload actions over and over again.

Compare this two screenshots that show the same content before and after the optimization.
The apricot colored parts of the bars stand for the status “in queue” while loading the page.

Before optimization
The “in queue” status means nothing less than: Wasted time of the user.

In this example, the loading time was reduced by 33%, the transferred data size was reduced by 65% and the number of requests to the server even by 80%.

After optimization
By using CSS sprites and merged CSS and Javascript files, there is no queue for the loading of the basic static content.

2. How to improve your static content

Besides caching, there are some principles to make the whole setup of static content more efficient right from the start of development.

  • Use CSS sprites2 for your layout graphics. It not only saves you a lot of traffic and loading time. If you got used to maintain your graphics like this, you’ll notice that it can be much more comfortable to have your layout elements e.g. in a single Photoshop file.
  • Don’t blow up the loading time with your CSS and Javascript files. Combine the files of each kind into one single file, minimize them (e.g. by removing line breaks and other unnecessary characters) and compress them using GZip to get the load even smaller.
    This is covered in this tutorial.

3. Automating the deployment using Ruby

This automation is written in the Ruby language3. So you need to have Ruby installed on your development computer. The installation is pretty simple on Windows4 and Mac OS X even ships with Ruby.

Please keep in mind: The scripts are completely independent from the language you’re using to run your site! You can also use them to deploy content e.g. for a PHP project.

If you’re not used to work on the command line, the next steps might look cryptic to you. Don’t hesitate, clench your teeth and take care that you always pass the correct path of the files to deal with. You only have to go through this once. When you’re finished, all you need to do is to type one single command to start the whole process.

To make it easier for you, this is the folder structure used for this tutorial:

+ css/
- fonts.css
- grids.css
- layout.css
- reset.css
- static.min.css (generated)
- static.min.css.gz (generated)

+ js/
- framework.js
- gallery.js
- plugin1.js
- plugin2.js
- start.js
- static.min.js (generated)
- static.min.js.gz (generated)
 
+ deploy/
- batch
- ftp.rb
- gzip.rb

index.php (or something similar)

Requirements for this tutorial

Don’t worry, besides Ruby you won’t need anything, that you don’t probably already have:

  • A simple text editor to save the source code.
  • A command line tool, like Windows cmd.exe or Mac OS X Terminal to call the scripts.
  • A FTP account to try out the upload script.
  • A project to enhance.
  • Optional: The Firefox add-on Firebug5 (or something similar for other browsers), to see the enhancements afterwards.

Juicer

Christian Johansen6 created a tool called Juicer7 which enables you to merge and minimize CSS and Javascript files. To install it on Windows, simply type

gem install juicer

in the command line. When you’re using Mac OS X use

sudo gem install juicer

After the successful install, Juicer will ask you to extend it with YUI Compressor8 and JSLint9 for Javascript compression and verification. You do this by typing

juicer install yui_compressor

and after that

juicer install jslint

in the command line.

Preparing your files

The good thing is, you don’t have to change anything in your present files. But to make sure, the files are merged in the order you want to, you need to set up two additional files.

Let’s assume you have four CSS files and five Javascript files:

<link rel="stylesheet" href="./css/reset.css" type="text/css" media="screen" />
<link rel="stylesheet" href="./css/fonts.css" type="text/css" media="screen" />
<link rel="stylesheet" href="./css/grids.css" type="text/css" media="screen" />
<link rel="stylesheet" href="./css/layout.css" type="text/css" media="screen" />

<script type="application/javascript" src="js/framework.js"></script>
<script type="application/javascript" src="js/plugin1.js"></script>
<script type="application/javascript" src="js/plugin2.js"></script>
<script type="application/javascript" src="js/gallery.js"></script>        
<script type="application/javascript" src="js/start.js"></script>

Create a new Javascript file, called static.js with the following content:

/**
 * @depends framework.js
 * @depends plugin1.js
 * @depends plugin2.js
 * @depends gallery.js
 * @depends start.js
 */

After that, create a CSS file static.css with this content:

@import url("reset.css");
@import url("fonts.css");
@import url("grids.css");
@import url("layout.css");

Now you’re ready to run Juicer in your command line.

For Javascript:

juicer merge -i --force ./js/static.js

The parameter -i means that the merging process won’t be cancelled, if JSLint thinks you have errors in your Javascript code. The parameter --force means older versions of the minified file will be overwritten.

For CSS:

juicer merge --force ./css/static.css

As a result you will see two new generated files named static.min.js and static.min.css. You probably want to know if they still work for your site, so go ahead and test it, by replacing the old bunch of link and script tags in your html header with the two new ones.

GZip Compression

When your minified files work fine, you can go on to compression. If you get Javascript errors or your CSS layout looks weird, you should re-check the order of the files to merge.

Below you see a small Ruby script that saves a gzipped copy of a file.

require 'zlib'

file_to_zip = ARGV[0]

puts "Gzipping #{file_to_zip}..."

base_name = File.basename(file_to_zip)

file_name_zip = "#{file_to_zip}.gz"

base_name_zip = "zip_#{base_name}"

File.open(file_name_zip, 'w') do |f|

  gz = Zlib::GzipWriter.new(f)
    
  IO.foreach(file_to_zip) {|x| 
    gz.write x
  }   
    
  gz.close
  
end

puts "Gzipped version saved as #{file_name_zip}"

Save it as gzip.rb and call it like this:

ruby gzip.rb ../js/static.min.js

When you look at your folder, you’ll notice a new file called static.min.js.gz. Now do the same for the CSS file:

ruby gzip.rb ../css/static.min.css

Important: Make sure that your server provides the right content encoding and content type information to the clients, so they understand that this files are gzipped content.
You can do this in many ways. For Apache, an example for the .htaccess file would be:

<FilesMatch ".(js.gz)$">
AddType text/javascript .gz
AddEncoding x-gzip .gz
</FilesMatch>

<FilesMatch ".(css.gz)$">
AddType text/css .gz
AddEncoding x-gzip .gz
</FilesMatch>

FTP-Upload

You’re on the home stretch. Now you have all improved files together and need to upload them to your host. Again, here’s a little Ruby script that does exactly that for you.

require 'net/ftp'

ftp_host = ARGV[0]
ftp_user = ARGV[1]
ftp_password = ARGV[2]


localfile = ARGV[3] #e.g. "../js/static.min.js.gz"
remote_dir = ARGV[4] #e.g. "www/js"

ftp = Net::FTP.open(ftp_host, ftp_user, ftp_password) 

puts "FTP - Status: #{ftp.status}."

puts "FTP - Go to directory: #{remote_dir}."
ftp.chdir(remote_dir)
puts "FTP - Uploading file: #{localfile}..."
ftp.putbinaryfile(localfile)

files = ftp.list puts "FTP - Your file was uploaded here:" puts files

ftp.close

Save it as upload.rb, put in the credentials of your host, eventually change the destination directory and then call it like that:

ruby ftp.rb example.org admin mysecret ../js/static.min.js www/js

Which stands for:
ruby ftp.rb ftp-host ftp-user ftp-password file-to-upload ftp-destination-folder

The minified Javascript file should be uploaded now. Repeat this for the CSS file and the gzipped versions of both.

Please note that the folders on the ftp server, where the files are copied to, must already exist.

Putting it all together

You got all the pieces of this puzzle and now you can finally put them together, by grouping the commands in a batch file. On Windows it would look like this:

@echo off

echo -------- MERGING JS FILES --------

call juicer merge -i --force ../js/static.js 

echo -------- FINISHED MERGING JS FILES --------

echo -------- MERGING CSS FILES --------

call juicer merge --force ../css/static.css

echo -------- FINISHED MERGING CSS FILES --------

echo -------- COMPRESSING FILES --------

ruby gzip.rb ../js/static.min.js

ruby gzip.rb ../css/static.min.css

echo -------- FINSISHED COMPRESSING FILES --------

echo -------- UPLOADING FILES --------

ruby ftp.rb example.org admin mysecret ../js/static.min.js www/js

ruby ftp.rb example.org admin mysecret ../js/static.min.js.gz www/js

ruby ftp.rb example.org admin mysecret ../css/static.min.css www/css

ruby ftp.rb example.org admin mysecret ../css/static.min.css.gz www/css

echo -------- FINISHED UPLOADING FILES --------

Save it in a file called e.g. batch.bat, insert your FTP credentials and call it like this:

cd deploy //switch to subdirectory
batch.bat

On OS X you can do it like that:

#!/bin/bash

echo -------- MERGING JS FILES --------

juicer merge -i --force ../js/static.js 

echo -------- FINISHED MERGING JS FILES --------

echo -------- MERGING CSS FILES --------

juicer merge --force ../css/static.css

echo -------- FINISHED MERGING CSS FILES --------

echo -------- COMPRESSING FILES --------

ruby gzip.rb ../js/static.min.js

ruby gzip.rb ../css/static.min.css

echo -------- FINSISHED COMPRESSING FILES --------

echo -------- UPLOADING FILES --------

ruby ftp.rb example.org admin mysecret ../js/static.min.js www/js

ruby ftp.rb example.org admin mysecret ../js/static.min.js.gz www/js

ruby ftp.rb example.org admin mysecret ../css/static.min.css www/css

ruby ftp.rb example.org admin mysecret ../css/static.min.css.gz www/css

echo -------- FINISHED UPLOADING FILES --------

Save it in a file called e.g. batch, insert your FTP credentials and call it like this:

cd deploy //switch to subdirectory
sh batch

And the content gets merged, minified, compressed and uploaded in one rush.
Additionally to the CSS and Javascript files, it would be a good idea, if the graphics file for the CSS sprites would be uploaded too? Just add an additional call of the upload script in the batch file. It can be used with any filetype.

4. In your template

Further development and bug fixing is hard to do in a minified file. But you can add an if-clause in your templates to vary the referencing of your files, depending on your environment.

Take the original files for your local development and the minified for your online version. Additionally you should check if the users browser supports gzipped content (most modern browsers do).

An example for PHP:

if($_SERVER["SERVER_NAME"] == "localhost") {
  //local development server - load all files
} else {
  if (substr_count($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip')){
    //production system - client accepts gzip     
  } else {
    //production system - client does not accept gzip
  } 
}

And an example for Ruby on Rails:

<% if RAILS_ENV == 'development' %>
  <%# local development server - load all files %>
<% else %>
  <% if self.request.env['HTTP_ACCEPT_ENCODING'].match(/gzip/) %>
    <%# production system - client accepts gzip %>
  <% else %>
    <%# production system - client does not accept gzip %>
  <% end %>
<% end %>

5. Get even faster with subdomains

Like mentioned before, most browsers only download two files per host simultaneously. You can bypass that rule by creating some subdomains for your static content and referencing the files through them.

For example, create a subdomain on your web hosting account, that’s called img.example.org, which points to example.org/img.

Do this for all of your folders, containing static content and use the subdomains to reference your resources:

img.example.org/sprites.jpg
css.example.org/static.min.css
js.example.org/static.min.js

This way, the rule won’t be applied and all files can be downloaded at the same time.

6. Conclusion

If you got all of this working for one of your projects, you surely recognized the advantages for you as a developer and for the users as the consumers of your content.

These examples don’t claim to be perfect. But if you didn’t approach to automate recurring tasks in your daily workflow as a developer, you hopefully have an idea now, how it could look like.

Always keep in mind, that computers were invented to spare you the boredom of repeating, simple tasks. So save your time for more important things.

Of course, this doesn’t have to be the end of the line. If you’re interested in the automatic deployment of whole applications, you should have a look at Capistrano10. Again, it’s written in Ruby, but you can also use it for PHP platforms.

Further Resources

Footnotes

  1. 1 http://kb.mozillazine.org/Network.http.max-persistent-connections-per-server
  2. 2 http://www.smashingmagazine.com/2009/04/27/the-mystery-of-css-sprites-techniques-tools-and-tutorials/
  3. 3 http://www.ruby-lang.org
  4. 4 http://rubyinstaller.rubyforge.org/wiki/wiki.pl
  5. 5 http://getfirebug.com/
  6. 6 http://www.cjohansen.no/en
  7. 7 http://www.cjohansen.no/en/ruby/juicer_a_css_and_javascript_packaging_tool
  8. 8 http://developer.yahoo.com/yui/compressor/
  9. 9 http://www.jslint.com/
  10. 10 http://www.capify.org/
  11. 11 http://developer.yahoo.com/performance/rules.html
  12. 12 http://developer.yahoo.com/yslow/
  13. 13 http://code.google.com/intl/en/speed/page-speed/index.html
  14. 14 http://betterexplained.com/articles/how-to-optimize-your-site-with-gzip-compression
  15. 15 http://www.uwserver.de/?p=16

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Christian Bäuerlein recently obtained his degree in Media System Design. He is passionate about Web development and creating all kinds of projects with JavaScript, PHP, Ruby and Java. You can follow him on this journey through his Twitter profile.

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  1. 1

    Jonathan Kupferman

    July 23, 2009 8:48 pm

    Excellent guide, anything that helps people improve their websites performance is a win for everyone. Aaron pointed out something that is incredibly important that I think should be stressed which is far-future expire headers. This is generally one of the simplest and easiest improvements since it usually only requires adding a line or two to a web server config file, those configs can be easily found online. Expire headers are especially important on sites where users generally visit multiple pages since one the second and third page they should be loading most assets from cache. Regardless of how compressed/minified your css/javascript/images are, it is almost always faster to load from cache then it is to re-download it becuase of internet latency.

    0
  2. 52

    For PHP development I make use of an ANT build script to do my deploys. The script compresses css/js using yui compressor http://javaflight.blogspot.com/2008/01/introducing-yui-compressor-ant-task.html, copies the files that are necessary and puts in a version number (useful if you are using a far future expire header but need to update js or css). GZip could be specified using mod_deflate (if you are using apache).

    0
  3. 103

    @Chris Thanks, it’s working now! ;)

    0
  4. 154

    5. Get even faster with subdomains

    There’s a DNS lookup overhead and may not always work.

    0
  5. 205

    Drupal already combines, compresses, and caches. You only need to add the subdomain trick if you have lots of other files filling the queue.

    0
  6. 256

    @peter: Drupal doesn’t have data:URI and CSS Sprites. Web Optimizer does

    0
  7. 307

    Of course this is proven time and again since this article was authored. My question is how to best handle that with SSL. If you mix secure and unsecure content, browsers warn, and viewers get nervous.

    One doesn’t want to buy SSL certificates for 4 domains (www.example.com, img.example.com, css.example.com, js.example.com). Even if you do with two domains (www.example.com, and static.example.com), you are now up to two SSL certificates, and two ip addresses. Is this the cost of doing business, or is there a better way to mix and match SSL with static content?

    0

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