sfCombinePlugin - 2.0.0

Combines and compresses JavaScript and CSS files

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sfCombinePlugin

sfCombinePlugin combines multiple JavaScript and CSS files into grouped JavaScript and CSS files at runtime, in order to minimize the number of HTTP requests required to render a given page. If you want to know why this is essential for your website performance, read Yahoo's Performance Research Findings.

Without sfCombinePlugin, a typical page requires many HTTP requests to get JavaScript and CSS files:

<head>
  ...
  <script type="text/javascript" src="/sf/js/prototype/prototype.js"></script>
  <script type="text/javascript" src="/sf/js/prototype/builder.js"></script>
  <script type="text/javascript" src="/sf/js/prototype/effects.js"></script>
  <link rel="stylesheet" type="text/css" media="screen" href="/css/main.css" />
  <link rel="stylesheet" type="text/css" media="screen" href="/css/layout.css" />
  <link rel="stylesheet" type="text/css" media="screen" href="/css/typo.css" />
</head>

With sfCombinePlugin, every page needs far fewer HTTP requests for all JavaScript code and style rules:

<head>
  ...
  <script type="text/javascript" src="/js-min/key/fa85b641ddfa951e57ba96bf990d76c4/v/1.js"></script>
  <link rel="stylesheet" type="text/css" media="screen" href="/css-min/key/21cf49fc13ba26430c5779c431e68995/v/1.css" 
  />
</head>

The JavaScript and CSS files are now served by a custom action of the sfCombine module, which combines and compresses several files into a single one.

If another page requires the same combination of files, it will include calls to the js and css actions of the sfCombine module with a similar key parameter. Otherwise, the plugin generates a different key, so that only the required files are loaded by the new page.

sfCombinePlugin is optimized and tested to work in professional environments:

  • The sfCombine module uses the symfony cache system to avoid executing the combination and compression routine for every request
  • HTTP 1.1 caching statements are added to let browsers and proxies keep the combined JavaScript and CSS files in their local cache
  • The combined files work in distributed environments, where you use several servers for load-balancing
  • No additional database query is required at runtime when an op-code cache engine (like APC) is available

Requirements

This plugin adds one database table, this is not required for usage however.

Installation

  1. Download the plugin.

    The easiest way to download sfCombinePlugin is to use the symfony command line:

    > php symfony plugin:install sfCombinePlugin --release=2.0.0
    

    Alternatively, if you don't have PEAR installed, you can download the latest package attached to this plugin's page and extract it under your project's plugins/ directory, or use svn:externals on your project's plugins directory.

  2. Rebuild your model. For Doctrine, that means calling the doctrine doctrine:build-model task:

    > php symfony doctrine:build-model
    

    This will create a model called sfCombinePlugin. For Propel, call the task propel:build-model. It will generate a model called sfCombine.

  3. Create the related sf_combine table in your database. Symfony can generate the necessary SQL code for you:

    > php symfony propel:build-sql
    

    Then, depending on your database engine, use the SQL code generated in data/sql/plugins.sfCombinePlugin.lib.model.schema.sql to insert the table in the database. For instance, for mySQL:

    > mysql -u username -p dbname < data/sql/plugins.sfCombinePlugin.lib.model.schema.sql
    

    For Doctrine, you need to call this task doctrine:build-sql.

  4. Enable the sfCombine module in your frontend application, via the settings.yml file.

    # in myproject/apps/frontend/config/settings.yml
    all:
      .settings:
        enabled_modules: [..., sfCombine]
  5. Replacing JavaScript and CSS calls in the layout

    Since symfony 1.3, the layout uses the regular include_javascripts() and include_stylesheets() helpers to output calls to the JavaScript and CSS files.

    Replace them with the include_combined_javascripts() and the include_combined_stylesheets() helpers. They belong to the sfCombine helper group, which must be declared prior to calling the helpers:

    // in apps/frontend/templates/layout.php
    <?php use_helper('sfCombine') ?>
    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
    <head>
      <?php include_http_metas() ?>
      <?php include_metas() ?>
      <?php include_title() ?>
      <link rel="shortcut icon" href="/favicon.ico" />
      <?php include_combined_stylesheets() ?>
      <?php include_combined_javascripts() ?>
    </head>
    <body>
      <?php echo $sf_flash->getRaw('notice') ?>
    </body>

    Note that if you use symfony 1.2 you must change the common filter class from sfCommonFilter to sfCombineFilter in your application filters.yml (See Including Javascript And CSS With A Filter chapter)

    You sometimes need to change the place where script and CSS inclusion tags appear in the source code. For instance, you may want to move the <script> tags to the bottom of the page, just before the </body>, to speed up page rendering. Or you may want to move the <link> tags before conditional comments in the header, to allow custom IE styles.

    // in apps/frontend/templates/layout.php
    <?php use_helper('sfCombine') ?>
    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
    <head>
      <?php include_http_metas() ?>
      <?php include_metas() ?>
      <?php include_title() ?>
      <link rel="shortcut icon" href="/favicon.ico" />
      <?php include_combined_stylesheets() ?>
      <!--[if lte IE 6]>
        <?php echo stylesheet_tag('ie6.css') ?>
      <![endif]-->
    </head>
    <body>
      <?php echo $sf_flash->getRaw('notice') ?>
      <?php include_combined_javascripts() ?>
    </body>
  6. Clear the cache to enable the autoloading to find the new classes

    > php symfony cc
    

Usage

Once installed, your application still works the same as usual. You need to manually enable the sfCombinePlugin features by way of configuration.

Configuration

Enable the plugin features through app.yml. You should enable the plugin only in the production and staging environments. This is because the plugin overhead is noticeable in the development environment, and because the plugin strips comments and whitespaces from your script and CSS files, making editions harder. So keep the plugin disabled in the development environment. The default setup is as follows:

# in apps/frontend/config/app.yml
dev:
  sfCombinePlugin:
    enabled:        false         # disable the plugin in development
 
default:
  sfCombinePlugin:
    enabled:        true          # enabling the plugin will combine script and css files into a single file
    asset_version:  0             # key to the asset version
    client_cache_max_age: 10      # enable the browser to keep a copy of the files for x days (false to disable)
    gzip:           true          # allow PHP gzipping of the combined JavaScript and CSS files to reduce bandwidth usage
    url_type:       key           # can be key, files, or base64 (note files can be buggy without an asset version)
    filter_include_unused_groups: true # whether to use the filter to include groups that havent been output
    timestamp:
      enabled: true               # suffix a timestamp where available to files for their asset version
      uncombinable: true          # timestamp files that aren't combinable
    js:
      combine: true               # whether or not to perform combining actions
      combine_skip: ~             # these files will not be combined (necessary when js code is based on js file name)
      include: true               # whether to allow the including of files
      include_suffixes:           # suffixes of files that can be included
          - .php
      include_skip: ~             # files that should be skipped on includes
      minify:       true          # process js files to shrink them
      minify_method: [sfCombineMinifierJsMin, minify]
      minify_method_options: []
      minify_skip_suffixes:       # files with this suffix will not be minified
          - .min.js
      minify_skip: ~              # these files will not be minified (useful when code is already minified)
      filename_comments: true     # include filenames of combined files in comments
      group_files: true           # minify all available files together in one minify action
      cache_minified_files: true  # cache minified versions of files (to not minify multiple times)
      route: sfCombineJs          # the route name js files will use
      inline_minify_method: ~
      inline_minify_method_options: ~
    css:
      combine: true               # whether or not to perform combining actions
      combine_skip: ~             # these files will not be combined
      include: true               # whether to allow the including of files
      include_suffixes:           # suffixes of files that can be included
          - .php
      include_skip: ~             # files that should be skipped on includes
      minify:       true          # process js files to shrink them
      minify_method: [sfCombineMinifierCssMin, minify]
      minify_method_options: []
      minify_skip_suffixes:       # files with this suffix should not be minified
          - .min.css
      minify_skip: ~              # these files will not be minified (useful when code is already minified)
      filename_comments: true     # include filenames of combined files in comments
      group_files: true           # minify all available files together in one minify action
      route: sfCombineCss         # the route name css files will use
      cache_minified_files: true  # cache minified versions of files (to not minify multiple times)
      keep_charset: true          # if there is a charset in a css file keep it
      prepend_imports: true       # move all imports to the top of a css file
      prepend_imports_warning:    # if imports are moved a warning to output
        Imports may be incorrectly placed, please remove for ideal combining
      inline_minify_method: ~
      inline_minify_method_options: ~

You can then overwrite in your app.yml files to set what you would like locally.

By default, sfCombinePlugin is disabled locally.

Caching

The plugin uses an aggressive caching strategy to avoid adding overhead in production. The pages served by the sfCombine module use the symfony template cache, including the (empty) layout. The consequence is that a change in any of the original script or CSS files do not result in a change in the combined script or CSS files. To allow changes in the combined files in production, you must clear the symfony template cache:

> php symfony clear-cache frontend template

Alternatively, clearing the whole symfony cache will also do the trick.

As the plugin uses the symfony template cache with layout, it is a perfect candidate for the sfSuperCachePlugin. With this plugin installed and enabled, requests to a combined JavaScript or CSS file can be answered by the web server alone, without even initializing symfony.

In addition to template cache, the sfCombine module includes an HTTP 1.1 Cache-Control: max_age header (see the Chapter 12 of the symfony book for more information). By default, it is set to 10 days, but you can change this value by modifying the app_sfCombinePlugin_client_cache_max_age setting. Set it to false to disable client-side caching (although this is not recommended).

Asset Versions

Since the combined files are sent with Cache-Control headers to invite browsers and proxies to keep these files in the cache, modifications in the original JavaScript and CSS files may never reach the users. Consider the following scenario:

  1. User A downloads the home page of your application
  2. This pages requires combined script and CSS files, and allows the browser to keep them in cache for 10 days
  3. A little while after (less than 10 days), you modify a CSS of the home page and push that file in production
  4. User A downloads the home page again. It still references the same combined files, which are still in cache, so the browser doesn't even send a request for them and misses the updated version.

To avoid this common pitfall, change the value of the app_sfCombinePlugin_asset_version setting every time you deploy a modified version of your script or CSS files to production. sfCombinePlugin uses this setting to generate the combined file key, so changing app_sfCombinePlugin_asset_version will change the key and force the browser to download an updated version.

Use whatever value you want for app_sfCombinePlugin_asset_version; a common practice is to use incremental integers.

Timestamping

An alternative way to stop pages being cached when they have changes is to enable timestamping this will check the files for the most recently modified timestamp and suffix the url with this timestamp

Including Javascript And CSS With A Filter

Each time you call $response->addJavascript() or $response->addStylesheet() in an action, use_javascript() or use_stylesheet() in a template, symfony stores the related file path in the response. In symfony 1.2, the common filter outputs the correct HTML tag to include these files (<script> or <link>) just before the closing </head> tag by default.

// in apps/frontend/templates/layout.php
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
  <?php include_http_metas() ?>
  <?php include_metas() ?>
  <?php include_title() ?>
  <link rel="shortcut icon" href="/favicon.ico" />
  <!-- This is where the common filter places <script> and <link> tags by default -->
</head>
<body>
  <?php echo $sf_flash->getRaw('notice') ?>
</body>

You must change the common filter class from sfCommonFilter to sfCombineFilter in your application filters.yml

# in myproject/apps/frontend/config/filters.yml
rendering: ~
web_debug: ~
security:  ~
 
# generally, you will want to insert your own filters here
 
cache:     ~
common:
  class: sfCombineFilter
flash:     ~
execution: ~

Troubleshooting JavaScript Errors

When browsing an application in production, you main notice new JavaScript errors that were not present before using the sfCombinePlugin. This is because some JavaScript files do not support combination and/or minification. Fortunately, the plugin allows you to exclude some files from the combination, minify or packing process, by using the combine_skip or minify_skip configuration settings.

For instance, the JavaScript file required by the TinyMCE rich text editor expects to find a <script> tag in the HTML document, with a src attribute referencing a file named tiny_mce.js (!). If the plugin combines tiny_mce.js with other files, you will end up with a JavaScript error saying "tinyMCE.baseURL is undefined", and the rich text editor will not display correctly. To disable the combining of this particular file only, add it to the app_sfCombinePlugin_js_combine_skip array:

# in apps/frontend/config/app.yml
all:
  sfCombinePlugin:
    js:
      combine_skip:    [/js/tiny_mce/tiny_mce.js]

Some other JavaScript files contains lines that don't end with a semicolon, and therefore will not support minification:

// this works, even with the missing semicolon at the end of the first line
$a = 'foo'
$b = 'bar';
 
// however, once minified, it doesn't work anymore
$a = 'foo' $b = 'bar';

If you cannot fix these errors in the source JavaScript files, you have to exclude these files from the minifying process:

# in apps/frontend/config/app.yml
all:
  sfCombinePlugin:
    js:
      minify_skip:    [/js/foo.js]

As a number of the files you have might already be minified you can specify a number of suffixes of files that will ensure their skipped and just combined in their minified state:

# in apps/frontend/config/app.yml
all:
  sfCombinePlugin:
    js:
      minify_skip_suffixes:    [min.js]

Be aware that most browsers stop the execution of a JavaScript file when they find a syntax error. Therefore, an error in a single file can put all your JavaScript code in jeopardy once the combination is active.

Using an Alternative Minifier

You may want to use switch the minifer which is used for either/both Javascript/Stylesheets. This can be done by changing the definition in the app.yml to reference one of the other classes packaged in this plugin, or by pointing to a method of your own that will perform it. You just need to specify a string / array to the method which call_user_func can interpret and you can specify an array of options for the method.

Database Cleanup

To allow the combine routine to work in distributed environments, sfCombinePlugin stores the list of files required by a page in the sf_combine table. As you add new pages or change versions, outdated records may stack up in this table. The plugin provides a cleanup task to periodically empty the sf_combine task. You can use it safely every once in a while (monthly for instance):

> php symfony combine:cleanup

Advanced Functionality

Assets can be assigned to groups when they are added e.g:

<?php use_javascript_grouped('foo.js', 'group'); ?>

This allows for global elements to be in their own group and page/section specific assets to be separate files to better leverage caching

Groups can be output in different places on the page, for example you can output all groups except group at the top of the page and another group just before the closing body.

// in apps/frontend/templates/layout.php
<?php use_helper('sfCombine') ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
  <head>
    <?php include_combined_javascripts('bodyJs', sfCombine::GROUP_EXCLUDE) ?>
  </head>
  <body>
    <?php include_combined_javascripts('bodyJs') ?>
  </body>
</html>

The filter helper can be set in the config to include any assets which are not included via the include_combine methods

PHP files can be used as assets and they will be parsed as long as including is enabled in sfCombine config. Parameters can be passed via query string. Other forms of dynamic generation should not be used as the file will be cached.

Script and style tags can have their content minified too by using the javascript_tag_minified() and style_tag_minified() helpers

Rather than calling both include_combined_javascripts() and include_combined_stylesheets() both can be included at the same time via include_combined_assets()

Known Issues

@import in CSS does not work correctly in combined files as it has to be moved to the top of the combined file to be syntactically valid using files as the url type can cause problems if asset version is 0 and timestamp is disabled.

License

This plugin is released under the MIT License, however it bundles a PHP port of Dean Edwards' Packer licensed in LGPL 2.1 and Minify Library licensed under New BSD.

Todo

  • More minifiers

Changelog

2011-03-18 | master

  • kevindew: removed paths that aren't needed and added arguments missing from functions

2010-06-06 | master

  • kevindew: symfony 1.4 work
  • kevindew: Javascript/CSS groups
  • kevindew: Database usage no longer required
  • kevindew: Parsing PHP JS/CSS files
  • kevindew: Handles external urls
  • kevindew: Allows symfony options for assets
  • kevindew: CSS relative URL fix
  • kevindew: @charset and @import handled in a limited way
  • kevindew: Temporarily only doctrine supported

2009-09-25 | trunk

  • heristop: Manages relative paths in css files
  • heristop: Fixed asset version feature

2009-08-24 | trunk

  • heristop: Fixed cache-control max-age which uses seconds
  • heristop: Enabled pjs extension

2009-06-06 | trunk

  • heristop: Delete extensions in order to compare assets to be ignored by the merge
  • heristop: Avoid compression for buggy versions of IE

2009-06-05 | trunk

  • heristop: Added better controls on assets to skip
  • heristop: Added Doctrine schema
  • heristop: Allow PHP gzipping of the combined JavaScript and CSS files to reduce bandwidth usage

2008-11-04 | trunk

  • francois: Fixed cache on sfCombine module (the cache layer needs a view, using renderText() bypasses the cache)
  • francois: Allowed certain files to be exempt from combination (e.g. tiny_mce.js)
  • francois: Fixed case when sfCombineFilter was applied to the output of the sfCombine module (in case a JavaScript file contains the </head> string)
  • francois: Fixed wrong way to access the plugin configuration (damn app.yml nesting levels)
  • francois: Avoid needless database queries when no JavaScript or CSS is present

2008-10-31

  • heristop, francois: Initial version