1 mod_ecs - Apache Embedded ClearSilver CGI Module 2 ------------------------------------------------------- 3 mod_ecs is based on a heavily modified version of mod_ecgi from: 4 http://www.webthing.com/software/mod_ecgi.html 5 6 This directory contains an Apache module which is designed to work with 7 the ClearSilver CGI Kit. The point of this Apache module is 8 performance, if your server is under sufficient load that the overhead 9 of forking and execing the CGI for every request is too much, this 10 module is for you. This module is also useful if you want some of the 11 benefits of having a long-lived program: ie, the CGI can maintain 12 connections to data sources such as databases or cache data in memory. 13 The chief disadvantage is the same thing: your CGI becomes a long lived 14 process, and you have to watch that you don't hold connections or memory 15 that you don't want to. You might want to look into the Apache 16 configuration directives for limiting the number of connections that 17 each child process handles: MaxRequestsPerChild. 18 19 If you are already using the full ClearSilver CGI Kit, all you need to 20 do to compile for the embedded ClearSilver is compile to a shared 21 library instead of to an executable. For instance, under Linux: 22 23 Executable: ld -o static.cgi -lneo_cgi -lneo_cs -lneo_util 24 Shared Library: ld -shared -fPic -o static.cso -lneo_cgi -lneo_cs -lneo_util 25 26 Also, remember not to call exit(), as this will cause the entire Apache 27 child to exit. 28 29 There are two extra functions you can have in your CGI that the embedded 30 ClearSilver module will try to find and call if they exist. They are: 31 void ECSInit(void); 32 and 33 void ECSCleanup(void); 34 35 The first is called when the embedded CGI is loaded, the second before 36 the embedded CGI is unloaded. 37 38 This module supports the following three Apache configuration 39 directives: 40 ECSReload <yes/no> 41 When yes, mod_ecs will stat the .cso every time its run, to see if the 42 file on disk has been updated. If it has been updated, it will reload 43 the shared file from disk. This incurs some performance overhead, and 44 when a change does occur, it removes most of the gains of ECSPreload. 45 Notice also that on many operating systems, changing a shared library 46 on disk that has been demand loaded can cause problems such as unexpected 47 core dumps. This setting is most useful for development environments where 48 speed/throughput requirements aren't as high, but constant change is a 49 factor. 50 ECSDepLib <path> 51 Brings the benefits of ECSPreload to dependent shared libraries. Will 52 cause mod_ecs to dlopen() the library at apache initialization time. 53 This can be avoided by using ECSPreload and having an ECSInit() 54 function in your library which does the shared library initialization. 55 ECSPreload <path> 56 This function can be used to preload any shared libraries that you might 57 be calling later. This allows you to hide the latency of load/init time 58 from your users by doing it once at apache initialization. 59 60 Requirements: 61 A later version of Apache 1.3.x, probably 1.3.12+. 62 63 To Compile: 64 To dynamically load this module (assuming your copy of Apache is 65 compiled to use mod_so), do: 66 67 /path/to/apxs -c mod_ecs.c 68 69 Optionally, to (semi-)automatically install the module, do: 70 /path/to/apxs -i -a -n ecs mod_ecs.so 71 72 Or, you can just edit your httpd.conf file yourself, adding the 73 following lines: 74 LoadModule ecs_module /path/to/installed/mod_ecs.so 75 # This line needs to be after and ClearModuleList command 76 AddModule mod_ecs.c 77 78 There are two ways to tell Apache that a file is an embedded ClearSilver 79 CGI shared library, both are by extension. Typically, we use the .cso 80 extension. You can either use AddHandler or AddType: 81 AddHandler ecs-cgi .cso 82 AddType application/x-ecs-cgi 83 84
