NAME Plack::App::MCCS - Minify, Compress, Cache-control and Serve static files from Plack applications VERSION version 0.003 EXTENDS Plack::Component SYNOPSIS # in your app.psgi: use Plack::Builder; use Plack::App::MCCS; my $app = sub { ... }; # be happy with the defaults: builder { mount '/static' => Plack::App::MCCS->new(root => '/path/to/static_files'); mount '/' => $app; }; # or tweak the app to suit your needs: builder { mount '/static' => Plack::App::MCCS->new( root => '/path/to/static_files', defaults => { valid_for => 86400, cache_control => ['private'], }, types => { '.htc' => { content_type => 'text/x-component', valid_for => 360, cache_control => ['no-cache', 'must-revalidate'], }, }, ); mount '/' => $app; }; DESCRIPTION "Plack::App::MCCS" is a Plack application that serves static files from a directory. It will prefer serving precompressed versions of files if they exist and the client supports it, and also prefer minified versions of CSS/JS files if they exist. If IO::Compress::Gzip is installed, "MCCS" will also automatically compress files that do not have a precompressed version and save the compressed versions to disk (so it only happens once and not on every request to the same file). If CSS::Minifier::XS and/or JavaScript::Minifier::XS are installed, it will also automatically minify CSS/JS files that do not have a preminified version and save them to disk (once again, will only happen once per file). This means "MCCS" needs to have write privileges to the static files directory. It would be better if files are preminified and precompressed, say automatically in your build process (if such a process exists). However, at some projects where you don't have an automatic build process, it is not uncommon to forget to minify/precompress. That's where automic minification/compression is useful. Most importantly, "MCCS" will generate proper Cache Control headers for every file served, including "Last-Modified", "Expires", "Cache-Control" and even "ETag" (ETags are created automatically, once per file, and saved to disk for future requests). It will appropriately respond with "304 Not Modified" for requests with headers "If-Modified-Since" or "If-None-Match" when these cache validations are fulfilled, without actually having to read the files' contents again. "MCCS" is active by default, which means that if there are some things you *don't* want it to do, you have to *tell* it not to. This is on purpose, because doing these actions is the whole point of "MCCS". WAIT, AREN'T THERE EXISTING PLACK MIDDLEWARES FOR THAT? Yes and no. A similar functionality can be added to an application by using the following Plack middlewares: * Plack::Middleware::Static or Plack::App::File - will serve static files * Plack::Middleware::Static::Minifier - will minify CSS/JS * Plack::Middleware::Precompressed - will serve precompressed .gz files * Plack::Middleware::Deflater - will compress representations with gzip/deflate algorithms * Plack::Middleware::ETag - will create ETags for files * Plack::Middleware::ConditionalGET - will handle "If-None-Match" and "If-Modified-Since" * Plack::Middleware::Header - will allow you to add cache control headers manually So why wouldn't I just use these middlewares? Here are my reasons: * "Static::Minifier" will not minify to disk, but will minify on every request, even to the same file (unless you provide it with a cache, which is not that better). This pointlessly increases the load on the server. * "Precompressed" is nice, but it relies on appending ".gz" to every request and sending it to the app. If the app returns "404 Not Found", it sends the request again without the ".gz" part. This might pollute your logs and I guess two requests to get one file is not better than one request. You can circumvent that with regex matching, but that isn't very comfortable. * "Deflater" will not compress to disk, but do that on every request. So once again, this is a big load on the server for no real reason. It also has a long standing bug where deflate responses fail on Firefox, which is annoying. * "ETag" will calculate the ETag again on every request. * "ConditionalGET" does not prevent the requested file to be opened for reading even if "304 Not Modified" is to be returned (since that check is performed later). I'm not sure if it affects performance in anyway, probably not. * No possible combination of any of the aformentioned middlewares seems to return proper (and configurable) Cache Control headers, so you need to do that manually, possibly with Plack::Middleware::Header, which is not just annoying if different file types have different cache settings, but doesn't even seem to work. * I don't really wanna use so many middlewares just for this functionality. "Plack::App::MCCS" attempts to perform all of this faster and better. Read the next section for more info. HOW DOES MCCS HANDLE REQUESTS? When a request is handed to "Plack::App::MCCS", the following process is performed: 1. Discovery: "MCCS" will try to find the requested path in the root directory. If the path is not found, "404 Not Found" is returned. If the path exists but is a directory, "403 Forbidden" is returned (directory listings might be supported in the future). 2. Examination: "MCCS" will try to find the content type of the file, either by its extension (relying on Plack::MIME for that), or by a specific setting provided to the app by the user (will take precedence). If not found (or file has no extension), "text/plain" is assumed (which means you should give your files proper extensions if possible). "MCCS" will also determine for how long to allow browsers/proxy caches/whatever caches to cache the file. By default, it will set a representation as valid for 86400 seconds (i.e. one day). However, this can be changed in two ways: either by setting a different default when creating an instance of the application (see more info at the "new()" method's documentation below), or by setting a specific value for certain file types. Also, "MCCS" by default sets the "public" option for the "Cache-Control" header, meaning caches are allowed to save responses even when authentication is performed. You can change that the same way. 3. Minification If the content type is "text/css" or "application/javascript", "MCCS" will try to find a preminified version of it on disk (directly, not with a second request). If found, this version will be marked for serving. If not found, and CSS::Minifier::XS or JavaScript::Minifier:XS are installed, "MCCS" will minify the file, save the minified version to disk, and mark it as the version to serve. Future requests to the same file will see the minified version and not minify again. "MCSS" searches for files that end with ".min.css" and ".min.js", and that's how it creates them too. So if a request comes to "style.css", "MCSS" will look for "style.min.css", possibly creating it if not found. The request path remains the same ("style.css") though, even internally. If a request comes to "style.min.css" (which you don't really want when using "MCCS"), the app will not attempt to minify it again (so you won't get things like "style.min.min.css"). 4. Compression If the client supports gzip encoding (deflate to be added in the future, probably), as noted with the "Accept-Encoding" header, "MCCS" will try to find a precompressed version of the file on disk. If found, this version is marked for serving. If not found, and IO::Compress::Gzip is installed, "MCCS" will compress the file, save the gzipped version to disk, and mark it as the version to serve. Future requests to the same file will see the compressed version and not compress again. "MCSS" searches for files that end with ".gz", and that's how it creates them too. So if a request comes to "style.css" (and it was minified in the previous step), "MCSS" will look for "style.min.css.gz", possibly creating it if not found. The request path remains the same ("style.css") though, even internally. 5. Cache Validation If the client provided the "If-Modified-Since" header, "MCCS" will determine if the file we're serving has been modified after the supplied date, and return "304 Not Modified" immediately if not. Unless the file has the 'no-store' cache control option, and if the client provided the "If-None-Match" header, "MCCS" will look for a file that has the same name as the file we're going to serve, plus an ".etag" prefix, such as "style.min.css.gz.etag" for example. If found, the contents of this file is read and compared with the provided ETag. If the two values are equal, "MCCS" will immediately return "304 Not Modified". 6. ETagging If an ".etag" file wasn't found in the previous step (and the file we're serving doesn't have the 'no-store' cache control option), "MCCS" will create one from the file's inode, last modification date and size. Future requests to the same file will see this ETag file, so it is not created again. 7. Headers and Cache-Control "MCCS" now sets headers, especially cache control headers, as appropriate: "Content-Encoding" is set to if a compressed version is returned. "Content-Length" is set with the size of the file in bytes. "Content-Type" is set with the type of the file (if a text file, charset string is appended, e.g. "text/css; charset=UTF-8"). "Last-Modified" is set with the last modification date of the file in HTTP date format. "Expires" is set with the date in which the file will expire (determined in stage 2), in HTTP date format. "Cache-Control" is set with the number of seconds the representation is valid for (unless caching of the file is not allowed) and other options (determined in stage 2). "Etag" is set with the ETag value (if exists). "Vary" is set with "Accept-Encoding". 8. Serving The file handle is returned to the Plack handler/server for serving. HOW DO WEB CACHES WORK ANYWAY? If you need more information on how caches work and cache control headers, read this great article . CLASS METHODS new( %opts ) Creates a new instance of this module. %opts *must* have the following keys: root - the path to the root directory where static files reside. %opts *may* have the following keys: encoding - the character set to append to content-type headers when text files are returned. Defaults to UTF-8. defaults - a hash-ref with some global defaults, the following options are supported: * valid_for: the default number of seconds caches are allowed to save a response. * cache_control: takes an array-ref of options for the "Cache-Control" header (all except for "max-age", which is automatically calculated from the resource's "valid_for" setting). * minify: give this option a false value (0, empty string, "undef") if you don't want "MCCS" to automatically minify CSS/JS files (it will still look for preminified versions though). * compress: like "minify", give this option a false value if you don't want "MCCS" to automatically compress files (it will still look for precompressed versions). types - a hash-ref with file extensions that may be served (keys must begin with a dot, so give '.css' and not 'css'). Every extension takes a hash-ref that might have valid_for and cache_control as with the "defaults" option, but also content_type with the content type to return for files with this extension (useful when Plack::MIME doesn't know the content type of a file). If you don't want something to be cached, you need to give the valid_for option (either in "defaults" or for a specific file type) a value of either zero, or preferably any number lower than zero, which will cause "MCCS" to set an "Expires" header way in the past. You should also pass the cache_control option "no_store" and probably "no_cache". When "MCCS" encounteres the "no_store" option, it does not automatically add the "max-age" option to the "Cache-Control" header. OBJECT METHODS call( \%env ) Plack automatically calls this method to handle a request. This is where the magic (or disaster) happens. CAVEATS AND THINGS TO CONSIDER * You can't tell "MCCS" to not minify/compress a specific file type yet but only disable minification/compression altogether (in the "defaults" setting for the "new()" method). * Directory listings are not supported yet (not sure if they will be). * Deflate compression is not supported yet (just gzip). * Caching middlewares such as Plack::Middleware::Cache and Plack::Middleware::Cached don't rely on Cache-Control headers (or so I understand) for their expiration values, which makes them less useful for applications that rely on "MCCS". You'll probably be better off with an external cache like Varnish if you want a cache on your application server. Even without a server cache, your application should still appear faster for users due to browser caching (and also server load should be decreased). * "Range" requests are not supported. See Plack::App::File::Range if you need that. * An "MCCS" middleware is not provided yet, just a Plack::App, so you need to use something like "mount" with Plack::Builder to use it. * "MCCS" is mounted on a directory and can't be set to only serve requests that match a certain regex. DIAGNOSTICS This module doesn't throw any exceptions, instead returning HTTP errors for the client and possibly issuing some "warn"s. The following list should help you to determine some potential problems with "MCCS": "failed gzipping %s: %s" This warning is issued when IO::Compress::Gzip fails to gzip a file. When it happens, "MCCS" will simply not return a gzipped representation. "Can't open ETag file %s.etag for reading" This warning is issued when "MCCS" can't read an ETag file, probably because it does not have enough permissions. The request will still be fulfilled, but it won't have the "ETag" header. "Can't open ETag file %s.etag for writing" Same as before, but when "MCCS" can't write an ETag file. "403 Forbidden" is returned for files that exist If a request for a certain file results in a "403 Forbidden" error, it probably means "MCCS" has no read permissions for that file. CONFIGURATION AND ENVIRONMENT "Plack::App::MCCS" requires no configuration files or environment variables. DEPENDENCIES "Plack::App::MCCS" depends on the following CPAN modules: * parent * Cwd * Fcntl * File::Spec::Unix * HTTP::Date * Module::Load::Conditional * Plack (obviously) "Plack::App::MCCS" will use the following modules if they exist, in order to minify/compress files (if they are not installed, "MCCS" will not be able to minify/compress on its own): * CSS::Minifier::XS * JavaScript::Minifier::XS * IO::Compress::Gzip INCOMPATIBILITIES WITH OTHER MODULES None reported. BUGS AND LIMITATIONS No bugs have been reported. Please report any bugs or feature requests to "bug-Plack-App-MCCS@rt.cpan.org", or through the web interface at . SEE ALSO Plack::Middleware::Static, Plack::App::File, Plack::Builder. ACKNOWLEDGMENTS Some of this module's code is based on Plack::App::File by Tatsuhiko Miyagawa and Plack::Middleware::ETag by Franck Cuny. AUTHOR Ido Perlmuter LICENSE AND COPYRIGHT Copyright (c) 2011, Ido Perlmuter "ido@ido50.net". This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either version 5.8.1 or any later version. See perlartistic and perlgpl. The full text of the license can be found in the LICENSE file included with this module. DISCLAIMER OF WARRANTY BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. 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