This module provides for loading of executable code and modules into the server at start-up or restart time.
Status: Base (Windows);
Experimental (Unix)
Source File: mod_so.c
Module Identifier:
so_module
Compatibility: Available in
Apache 1.3 and later.
This is an experimental module. On selected operating systems it can be used to load modules into Apache at runtime via the Dynamic Shared Object (DSO) mechanism, rather than requiring a recompilation.
On Unix, the loaded code typically comes from shared object files (usually with .so extension), whilst on Windows this module loads DLL files. This module is only available in Apache 1.3 and up.
In previous releases, the functionality of this module was provided for Unix by mod_dld, and for Windows by mod_dll. On Windows, mod_dll was used in beta release 1.3b1 through 1.3b5. mod_so combines these two modules into a single module for all operating systems.
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.
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.
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.
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 MODULE_VAR_EXPORT (defined in the Apache
header files) to your module's module record definition. For
example, if your module has:
module foo_module;
Replace the above with:
module MODULE_VAR_EXPORT foo_module;
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.
Now, create a DLL containing your module. You will need to link this against the ApacheCore.lib export library that is created when the ApacheCore.dll shared library is compiled. You may also have to change the compiler settings to ensure that the Apache header files are correctly located.
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.
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.
For example:
LoadFile libexec/libxmlparse.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 (Unix, and for Windows as
of Apache 1.3.15):
LoadModule status_module modules/mod_status.so
Example (Windows prior to Apache 1.3.15, and some 3rd party modules):
LoadModule foo_module modules/ApacheModuleFoo.dll
Note that all modules bundled with the Apache Win32 binary distribution were renamed as of Apache version 1.3.15.
Win32 Apache modules are often distributed with the old style names, or even a name such as libfoo.dll. Whatever the name of the module, the LoadModule directive requires the exact filename, no assumption is made about the filename extension.
See also: AddModule and ClearModuleList