Apache Module mod_so

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Description:	Loading of executable code and -modules into the server at start-up or restart time
Status:	Extension
Module Identifier:	so_module
Source File:	mod_so.c
Compatibility:	This is a Base module (always included) on -Windows

Summary

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On selected operating systems this module can be used to - load modules into Apache at runtime via the Dynamic Shared Object (DSO) mechanism, - rather than requiring a recompilation.

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On Unix, the loaded code typically comes from shared object - files (usually with .so extension), on Windows - this may either the .so or .dll - extension.

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Warning

Apache 1.3 modules cannot be directly used - with Apache 2.0 - the module must be modified to dynamically - load or compile into Apache 2.0.

Topics

Creating Loadable Modules for Windows

Creating Loadable Modules for Windows

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Note

The module name format changed for Windows - with Apache 1.3.15 and 2.0 - the modules are now named as - mod_foo.so

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While mod_so still loads modules with - ApacheModuleFoo.dll names, the new naming convention is - preferred; if you are converting your loadable module for 2.0, - please fix the name to this 2.0 convention.

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The Apache module API is unchanged between the Unix and - Windows versions. Many modules will run on Windows with no or - little change from Unix, although others rely on aspects of the - Unix architecture which are not present in Windows, and will - not work.

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When a module does work, it can be added to the server in - one of two ways. As with Unix, it can be compiled into the - server. Because Apache for Windows does not have the - Configure program of Apache for Unix, the module's - source file must be added to the ApacheCore project file, and - its symbols must be added to the - os\win32\modules.c file.

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The second way is to compile the module as a DLL, a shared - library that can be loaded into the server at runtime, using - the LoadModule - directive. These module DLLs can be distributed and run on any - Apache for Windows installation, without recompilation of the - server.

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To create a module DLL, a small change is necessary to the - module's source file: The module record must be exported from - the DLL (which will be created later; see below). To do this, - add the AP_MODULE_DECLARE_DATA (defined in the - Apache header files) to your module's module record definition. - For example, if your module has:

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- module foo_module; -

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Replace the above with:

- module AP_MODULE_DECLARE_DATA foo_module; -

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Note that this will only be activated on Windows, so the - module can continue to be used, unchanged, with Unix if needed. - Also, if you are familiar with .DEF files, you can - export the module record with that method instead.

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Now, create a DLL containing your module. You will need to - link this against the libhttpd.lib export library that is - created when the libhttpd.dll shared library is compiled. You - may also have to change the compiler settings to ensure that - the Apache header files are correctly located. You can find - this library in your server root's modules directory. It is - best to grab an existing module .dsp file from the tree to - assure the build environment is configured correctly, or - alternately compare the compiler and link options to your - .dsp.

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This should create a DLL version of your module. Now simply - place it in the modules directory of your server - root, and use the LoadModule - directive to load it.

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LoadFile Directive

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Description:	Link in the named object file or library
Syntax:	`LoadFile filename [filename] ...`
Context:	server config
Status:	Extension
Module:	mod_so

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The LoadFile directive links in the named object files or - libraries when the server is started or restarted; this is used - to load additional code which may be required for some module - to work. Filename is either an absolute path or - relative to ServerRoot.

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For example:

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LoadFile libexec/libxmlparse.so

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LoadModule Directive

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Description:	Links in the object file or library, and adds to the list -of active modules
Syntax:	`LoadModule module filename`
Context:	server config
Status:	Extension
Module:	mod_so

The LoadModule directive links in the object file or library - filename and adds the module structure named - module to the list of active modules. Module - is the name of the external variable of type - module in the file, and is listed as the Module Identifier - in the module documentation. Example:

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- LoadModule status_module modules/mod_status.so -

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loads the named module from the modules subdirectory of the - ServerRoot.

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