mod_so - Apache HTTP Server Version 2.4









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Apache HTTP Server Version 2.4



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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


    On selected operating systems this module can be used to
    load modules into Apache HTTP Server 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), on Windows
    this may either be the .so or .dll
    extension.

    Warning
    Modules built for one major version of the Apache HTTP Server
    will generally not work on another. (e.g. 1.3 vs. 2.0, or 2.0 vs.
    2.2) There are usually API changes between one major version and
    another that require that modules be modified to work with the new
    version.
    

Topics

 Creating Loadable Modules for Windows
Directives

 LoadFile
 LoadModule

Bugfix checklisthttpd changelogKnown issuesReport a bugSee also

Comments


Creating Loadable Modules for Windows

    Note
    On Windows, where loadable files typically have a file extension
    of .dll, Apache httpd modules are called
    mod_whatever.so, just as they are on other platforms.
    However, you may encounter third-party modules, such as PHP for
    example, that continue to use the .dll convention.

    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.

    The Apache httpd 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 httpd for Windows does not have the
    Configure program of Apache httpd 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 httpd 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 AP_MODULE_DECLARE_DATA (defined in the
    Apache httpd header files) to your module's module record definition.
    For example, if your module has:


    module foo_module;


    Replace the above with:

    module AP_MODULE_DECLARE_DATA 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 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 httpd 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.

    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.



LoadFile Directive

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


    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"





LoadModule Directive

Description:Links in the object file or library, and adds to the list
of active modules
Syntax:LoadModule module filename
Context:server config, virtual host
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.

    For example:

    LoadModule status_module "modules/mod_status.so"


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




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