Preoperation and Postoperation Plug-Ins

When processing client requests and when sending information to clients, Directory Server calls preoperation and postoperation plug-in functions.

Preoperation Plug-Ins

Preoperation plug-ins are called before a client request is processed. Use preoperation plug-ins to validate attribute values, and to add to and delete from attributes that are provided in a request, for example.

Postoperation Plug-Ins

Postoperation plug-ins are called after a client request has been processed and all results have been sent to the client, whether or not the operation completes successfully. Use postoperation plug-ins to send alerts, or to send alarms. Also use postoperation plug-ins to perform auditing work, or to perform cleanup work.

Several operations support the use of preoperation and postoperation plug-in functions. Operations include abandon, add, bind, compare, delete, modify, modify RDN, search, send entry, send referral, send result, and unbind. The plug-ins function regardless of the Directory Server front end contacted by the client application.

As is the case for other plug-in functions, slapi_pblock_set() is used in the plug-in initialization function to register preoperation and postoperation plug-in functions. slapi_pblock_set() is described in Part II, Directory Server Plug-In API Reference.

Registration Identifiers

Preoperation plug-in registrations use IDs of the form SLAPI_PLUGIN_PRE_operation_FN. Postoperation registrations use IDs of the form SLAPI_PLUGIN_POST_operation_FN. Here, operation is one of ABANDON, ADD, BIND, COMPARE, DELETE, ENTRY (sending entries to the client), MODIFY, MODRDN, REFERRAL (sending referrals to the client), RESULT (sending results to the client), SEARCH, or UNBIND.

Part II, Directory Server Plug-In API Reference describes these IDs. Refer also to install-path/include/slapi-plugin.h for the complete list of IDs used at build time.

The following example demonstrates how the functions are registered with Directory Server by using the appropriate registration IDs.

Example 5-1 Registering Postoperation Functions (testpostop.c)

#include "slapi-plugin.h"

Slapi_PluginDesc postop_desc = {
    "test-postop",                     /* plug-in identifier         */
    "Oracle Corporation (test)",       /* vendor name                */
    "11.1.1.3.0",                      /* plug-in revision number    */
    "Sample post-operation plug-in"    /* plug-in description        */
};

static Slapi_ComponentId * postop_id;  /* Used to set log            */

/* Register the plug-in with the server. */
#ifdef _WIN32
__declspec(dllexport)
#endif
int
testpostop_init(Slapi_PBlock * pb)
{
    int rc = 0;                        /* 0 means success            */
    rc |= slapi_pblock_set(            /* Plug-in API version        */
        pb,
        SLAPI_PLUGIN_VERSION,
        SLAPI_PLUGIN_CURRENT_VERSION
    );
    rc |= slapi_pblock_set(            /* Plug-in description        */
        pb,
        SLAPI_PLUGIN_DESCRIPTION,
        (void *) &postop_desc
    );
    rc |= slapi_pblock_set(            /* Open log at startup        */
        pb,
        SLAPI_PLUGIN_START_FN,
        (void *) testpostop_set_log
    );
    rc |= slapi_pblock_set(            /* Post-op add function       */
        pb,
        SLAPI_PLUGIN_POST_ADD_FN,
        (void *) testpostop_add
    );
    rc |= slapi_pblock_set(            /* Post-op modify function    */
        pb,
        SLAPI_PLUGIN_POST_MODIFY_FN,
        (void *) testpostop_mod
    );
    rc |= slapi_pblock_set(            /* Post-op delete function    */
        pb,
        SLAPI_PLUGIN_POST_DELETE_FN,
        (void *) testpostop_del
    );
    rc |= slapi_pblock_set(            /* Post-op modrdn function    */
        pb,
        SLAPI_PLUGIN_POST_MODRDN_FN,
        (void *) testpostop_modrdn
    );
    rc |= slapi_pblock_set(            /* Close log on shutdown      */
        pb,
        SLAPI_PLUGIN_CLOSE_FN,
        (void *) testpostop_free_log
    );
    /* Plug-in identifier is required for internal search.           */
    rc |= slapi_pblock_get(pb, SLAPI_PLUGIN_IDENTITY, &postop_id);
    return (rc);
}

In addition to its postoperation functions, the plug-in that is shown in the preceding example registers a function. The plug-in opens a log file at startup. The plug-in closes the log file at shutdown. For details, refer to install-path/examples/testpostop.c.

Location of Plug-In Examples

Plug-in examples are located in install-path/examples/.