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Pipe

Put your assets into the pipe and smoke them.

Pipe is an asset pipeline in the spirit of Sprockets. It's meant as the practical way for managing assets. It aims to provide a useful out of the box setup for managing assets and support for common preprocessor languages found in the web environment, like CoffeeScript or LESS.

What Pipe provides for you:

• Out of the box support for Less and CoffeeScript
• Integrated Dependency Managment.
• Support for multiple asset load paths, which allows you to untie your application's libraries from your vendor libraries.
• Tries to take the pain out of asset deployment, by being designed for dealing with cache busting and compression.

Install

Get composer (if you haven't):

wget http://getcomposer.org/composer.phar

Then add this to a composer.json in your project's root:

{
    "require": {
        "chh/pipe": "*"
    }
}

Now install:

php composer.phar install

Getting Started

Environment

First you need an instance of Pipe\Environment. The environment holds your load paths, is used to retrieve assets and maps processors/engines to your assets.

The environment consists of multiple load paths. When retrieving an asset, it's looked up in every directory of the load paths. This way you can split your assets up in multiple directories, for example vendor_assets and assets.

To add some load paths, use the appendPath method. Paths can be prepended by the prependPath method. But use this carefully, because you can override assets this way.

Assets are retrieved by accessing an index of the environment instance, or by calling the find method.

The find method returns either null when no asset was found or an asset instance.

To get the asset's processed body, use the getBody method.

You can get the asset's last modified timestamp with the getLastModified method.

Dumping an Asset to a File

To dump an asset to a file, use the write method.

The write method takes an array of options:

• dir (string): The directory is the prefix of the file. A hash of the asset's contents is automatically included in the resulting filename.
• include_digest (bool): Should the SHA1 hash of the asset's contents be included in the filename?
• compress (bool): Compresses the contents with GZIP and writes it with an .gz extension.

Enabling Compression

You can turn on compression by setting the js_compressor and css_compressor config keys, or by calling setJsCompressor or setCssCompressor on an Environment instance.

Supported Javascript Compressors:

• uglify_js, uses the popular Uglify JS compressor built for NodeJS. Install with npm -g install uglify-js.
• yuglify_js, Compressor built upon Uglify JS, and behaves like YUI compressor. Install with npm -g install yuglify.

Supported CSS Compressors:

• yuglify_css, uses the Yuglify compressor's ability to compress CSS using CSSmin. Requires the yuglify NPM package.

Example:

Directives

Each file with content type application/javascript or text/css is processed by the DirectiveProcessor. The DirectiveProcessor parses the head of these files for special comments starting with an equals sign.

The arguments for each directive are split by the Bourne Shell's rules. This means you have to quote arguments which contain spaces with either single or double quotes.

require

Usage:

require <path>

The require directive takes an asset path as argument, processes the asset and puts the dependency's contents before the asset's contents.

The path can also start with ./, which skips the load path for the path resolution and looks up the file in the same path as the current asset.

depend_on

Usage:

depend_on <path>

Defines that the path is a dependency of the current asset, but does not process anything. Assets defined this way get considered when the last modified time is calculated, but the contents get not prepended.

require_tree

Usage:

require_tree <path>

Requires all files found in the directory specified by path.

For example, if you have a directory for all individual widgets and a widget base prototype, then you could require_tree the widgets/ directory. This way every developer can just drop a file into the widgets/ directory without having to maintain a massive list of individual assets.

// index.js
//= require ./widget_base
//= require_tree ./widgets

Engines

Engines are used to process assets before they're dumped. Each engine is mapped to one or more file extension (e.g. CoffeeScript to .coffee). Each asset can be processed by one or more engines. Which engines are used on the asset and their order is determined by the asset's file extensions.

For example, to process an asset first by the PHP engine and then by the LESS compiler, give the asset the .less.php suffix.

Here's a list of the engines provided by default and their mapping to file extensions:

Under the hood, Pipe Engines are meta-template templates. Look at its README for more information on building your own engines.

To add an engine class to Pipe, use the environment's registerEngine method, which takes the engine's class name as first argument and an array of extensions as second argument.

Serving Assets dynamically.

Pipe includes a Pipe\Server which is able to serve assets dynamically via HTTP. The server is designed to be called in .php file, served via mod_php or FastCGI.

To use the dynamic asset server, you've to additionally require symfony/http-foundation. The require section of your composer.json should look like this:

{
    "require": {
        "chh/pipe": "*@dev",
        "symfony/http-foundation": "*"
    }
}

The server's constructor expects an environment as only argument. You can either construct the environment from scratch or use the Config class.

Put this in a file named assets.php:

The server resolves all request URIs relative to the environment's load path. So to render the Javascript file js/index.js you would request the URI /assets.php/js/index.js.

The server also applies some conditional caching via Last-Modified and If-Not-Modified-Since HTTP headers. Should a change to a dependency not be instantly visible, try to make a hard refresh in your browser or clear your browser's cache.

Preparing Assets for Production Deployment

It's a good idea to compile assets in a way that they don't need the runtime support of Pipe. The Pipe\Manifest class is responsible for just that.

The Manifest is used to compile assets and writes a JSON encoded file which maps the logical paths (which the app knows anyway) to the paths including the digest (which the app can't know in advance).

To add a file to the manifest, call the manifest's compile method:

<?php

$env = new \Pipe\Environment;
$env->appendPath('assets/javascripts');

$manifest = new \Pipe\Manifest($env, 'build/assets/manifest.json');
$manifest->compile('index.js');

This creates the index-<SHA1 digest>.js file, and a manifest.json both in the build/assets directory.

This file looks a bit like this:

{
    "assets": {
        "index.js": "index-0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33.js"
    }
}

Then deploy everything located in build/assets, e.g. to some CDN or static file server.

An app running in a production environment could use the manifest like this, to create links to the assets:

<?php

# Better cache this, but omitted for brevity
$manifest = json_decode(file_get_contents('/path/to/manifest.json'), true);

# Path where the contents of "build/assets" are deployed.
# Could be a path to a CDN.
$prefix = "/assets";

printf('<script type="text/javascript" src="%s/%s"></script>', $prefix, $manifest['assets']['index.js']);

License

The MIT License

Copyright (c) 2012 Christoph Hochstrasser

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.