Project

General

Profile

Docs ModCompress » History » Revision 16

Revision 15 (moo, 2007-07-07 15:28) → Revision 16/39 (moo, 2007-07-07 15:29)

[[TracNav(DocsToc))]] 
 [[TracNav(DocsToc))] 
 {{{ 
 #!rst 
 ================== 
 Output Compression 
 ================== 

 -------------------- 
 Module: mod_compress 
 -------------------- 

 .. meta:: 
   :keywords: lighttpd, compress 
  
 .. contents:: Table of Contents 

 Description 
 =========== 

 Output compression reduces the network load and can improve the overall 
 throughput of the webserver. All major http-clients support compression by 
 announcing it in the Accept-Encoding header. This is used to negotiate the  
 most suitable compression method. We support deflate, gzip and bzip2. 

 deflate (RFC1950, RFC1951) and gzip (RFC1952) depend on zlib while bzip2  
 depends on libbzip2. bzip2 is only supported by lynx and some other console 
 text-browsers. 

 We currently limit to compression support to static files. 

 Caching 
 ------- 

 mod_compress can store compressed files on disk to optimize the compression 
 on a second request away. As soon as compress.cache-dir is set the files are 
 compressed.  

 (You will need to create the cache directory if it doesn't already exist. The web server will not do this for you.    The directory will also need the proper ownership.    For Debian/Ubuntu the user and group ids should both be www-data.) 

 The names of the cache files are made of the filename, the compression method 
 and the etag associated to the file. 

 Cleaning the cache is left to the user. A cron job deleting files older than 
 10 days could do it: :: 

   find /var/www/cache -type f -mtime +10 | xargs -r rm 

 Limitations 
 ----------- 

 The module limits the compression of files to files smaller than 128 MByte and 
 larger than 128 Byte. 

 The lower limit is set as small files tend to become larger by compressing due 
 to the compression headers, the upper limit is set to work sensibly with 
 memory and cpu-time. 

 Options 
 ======= 

 compress.cache-dir 
   name of the directory where compressed content will be cached 

   e.g.: :: 
  
     compress.cache-dir = "/var/www/cache/" 
    
     # even better with virt-hosting 
     $HTTP["host"] == "docs.example.org" { 
       compress.cache-dir = "/var/www/cache/docs.example.org/" 
     } 
    
   Default: not set, compress the file for every request 

 compress.filetype 
   mimetypes which might get compressed 
  
   e.g.: :: 
  
     compress.filetype             = ("text/plain", "text/html") 

   Keep in mind that compressed JavaScript and CSS files are broken in some 
   browsers. Not setting any filetypes will result in no files being compressed. 

   Default: not set 

 compress.max-filesize  
   maximum size of the original file to be compressed kBytes. 

   This is meant to protect the server against DoSing as compressing large 
   (let's say 1Gbyte) takes a lot of time and would delay the whole operation 
   of the server. 

   There is a hard upper limit of 128Mbyte. 

   Default: unlimited (== hard-limit of 128MByte) 

 Display compressed files 
 ======================== 

 If you enable mod_compress, and you want to force clients to uncompress and display compressed text files, please force mimetype to nothing. 
 Exemple : 
 If you want to add headers for uncompress and display diff.gz files , add this section in your conf : :: 

   $HTTP["url"] =~ "\.diff\.gz" { 
     setenv.add-response-header = ( "Content-Encoding" => "gzip" ) 
     mimetype.assign = () 
   } 

  
 Compressing Dynamic Content 
 =========================== 

 PHP 
 --- 

 To compress dynamic content with PHP please enable :: 

   zlib.output_compression = 1 
   zlib.output_handler = On 
  
 in the php.ini as PHP provides compression support by itself. 

 TurboGears 
 ---------- 

 To compress dynamic content with TurboGears please enable :: 

   [/] 
   gzip_filter.on = True 
   gzip_filter.mime_types = ["application/x-javascript", "text/javascript", "text/html", "text/css", "text/plain"] 

 in the config/app.cfg file in your TurboGears application.    The above lines should already be in the file.    You just need to remove the comment symbol in front of the lines to make them active. 

 }}}