Chapter 6 Writing Pre/Post-Operation Plug-ins

This chapter explains how to write functions that the Netscape Directory Server (Directory Server) calls before and after executing an LDAP operation. These functions are called pre-operation and post-operation plug-in functions.

How Pre/Post-Operation Plug-ins Work

The Directory Server can perform the following LDAP operations: bind, unbind, search, modify, add, delete, modifyRDN, compare, and abandon.


Note	The Directory Server can also perform extended operations as defined in the LDAPv3 protocol. For information on implementing plug-in functions to execute extended operations, see chapter 10, "Writing Extended Operation Plug-ins."

You can configure the Directory Server to call your custom plug-in functions before and after executing any of these LDAP operations.

For example, you can write a pre-operation function that validates an entry before the server performs an LDAP add operation. An example of a post-operation plug-in function would be one that sends a notification to a user after their entry has been modified by an LDAP modify operation.

You can also set up the Directory Server to call your own plug-in functions before and after:

Sending an LDAP entry back to the client.
Sending an LDAP result code back to the client.
Sending an LDAP referral back to the client.

Figure 6-1 illustrates how the Directory Server front-end calls pre-operation and post-operation functions before and after executing an LDAP operation.

When processing a request, the Directory Server will call all registered pre-operation functions before it calls the backend to service the request. All pre-operation functions must return before the front-end calls the associated backend function.

Figure 6-1 Calling Pre-Operation and Post-Operation Plug-in Functions

Types of Pre-Operation and Post-Operation Functions

As is the case with other server plug-in functions, pre-operation functions and post-operation functions are specified in a parameter block that you can set on server startup. Each function corresponds to an ID in the parameter block. In your initialization function, you can call the slapi_pblock_set() function to specify the name of your function that corresponds to the pre-operation or post-operation function. For more information on the parameter block, see Getting Data from the Parameter Block.

Types of Pre-Operation Functions

Table 6-1 lists the Directory Server pre-operation functions and the purpose of each function.

Table 6-1 Functions Called before the Directory Server Executes an Operation


ID in Parameter Block	Description
SLAPI_PLUGIN_PRE_BIND_FN	Specifies the function called before the Directory Server executes an LDAP bind operation. For information on writing this type of function, see Processing an LDAP Bind Operation.
SLAPI_PLUGIN_PRE_UNBIND_FN	Specifies the function called before the Directory Server executes an LDAP unbind operation. For information on writing this type of function, see Processing an LDAP Unbind Operation.
SLAPI_PLUGIN_PRE_SEARCH_FN	Specifies the function called before the Directory Server executes an LDAP search operation. For information on writing this type of function, see Processing an LDAP Search Operation.
SLAPI_PLUGIN_PRE_COMPARE_FN	Specifies the function called before the Directory Server executes an LDAP compare operation. For information on writing this type of function, see Processing an LDAP Compare Operation.
SLAPI_PLUGIN_PRE_ADD_FN	Specifies the function called before the Directory Server executes an LDAP add operation. For information on writing this type of function, see Processing an LDAP Add Operation.
SLAPI_PLUGIN_PRE_MODIFY_FN	Specifies the function called before the Directory Server executes an LDAP modify operation. For information on writing this type of function, see Processing an LDAP Modify Operation.
SLAPI_PLUGIN_PRE_MODRDN_FN	Specifies the function called before the Directory Server executes an LDAP modifyRDN operation. For information on writing this type of function, see Processing an LDAP Modify RDN Operation.
SLAPI_PLUGIN_PRE_DELETE_FN	Specifies the function called before the Directory Server executes an LDAP delete operation. For information on writing this type of function, see Processing an LDAP Delete Operation.
SLAPI_PLUGIN_PRE_ABANDON_FN	Specifies the function called before the Directory Server executes an LDAP abandon operation. For information on writing this type of function, see Processing an LDAP Abandon Operation.
SLAPI_PLUGIN_PRE_ENTRY_FN	Specifies the function called before the Directory Server sends an entry back to the client (for example, when you call slapi_send_ldap_search_entry(), the pre-operation entry function is called before the entry is sent back to the client).
SLAPI_PLUGIN_PRE_REFERRAL_FN	Specifies the function called before the Directory Server sends a referral back to the client (for example, when you call slapi_str2filter(), the pre-operation referral function is called before the referral is sent back to the client).
SLAPI_PLUGIN_PRE_RESULT_FN	Specifies the function called before the Directory Server sends a result code back to the client (for example, when you call slapi_send_ldap_result(), the pre-operation result function is called before the result code is sent back to the client).

Types of Post-Operation Functions

Table 6-2 lists the Directory Server post-operation functions and the purpose of each function.

Table 6-2 Functions Called after the Directory Server Executes an Operation


ID in Parameter Block	Description
SLAPI_PLUGIN_POST_BIND_FN	Specifies the function called after the Directory Server executes an LDAP bind operation. For information on writing this type of function, see Processing an LDAP Bind Operation.
SLAPI_PLUGIN_POST_UNBIND_FN	Specifies the function called after the Directory Server executes an LDAP unbind operation. For information on writing this type of function, see Processing an LDAP Unbind Operation.
SLAPI_PLUGIN_POST_SEARCH_FN	Specifies the function called after the Directory Server executes an LDAP search operation. For information on writing this type of function, see Processing an LDAP Search Operation.
SLAPI_PLUGIN_POST_COMPARE_FN	Specifies the function called after the Directory Server executes an LDAP compare operation. For information on writing this type of function, see Processing an LDAP Compare Operation.
SLAPI_PLUGIN_POST_ADD_FN	Specifies the function called after the Directory Server executes an LDAP add operation. For information on writing this type of function, see Processing an LDAP Add Operation.
SLAPI_PLUGIN_POST_MODIFY_FN	Specifies the function called after the Directory Server executes an LDAP modify operation. For information on writing this type of function, see Processing an LDAP Modify Operation.
SLAPI_PLUGIN_POST_MODRDN_FN	Specifies the function called after the Directory Server executes an LDAP modifyRDN operation. For information on writing this type of function, see Processing an LDAP Modify RDN Operation.
SLAPI_PLUGIN_POST_DELETE_FN	Specifies the function called after the Directory Server executes an LDAP delete operation. For information on writing this type of function, see Processing an LDAP Delete Operation.
SLAPI_PLUGIN_POST_ABANDON_FN	Specifies the function called after the Directory Server executes an LDAP abandon operation. For information on writing this type of function, see Processing an LDAP Abandon Operation.
SLAPI_PLUGIN_POST_ENTRY_FN	Specifies the function called after the Directory Server sends an entry back to the client (for example, when you call slapi_send_ldap_search_entry(), the post-operation entry function is called after the entry is sent back to the client).
SLAPI_PLUGIN_POST_REFERRAL_FN	Specifies the function called after the Directory Server sends a referral back to the client (for example, when you call slapi_str2filter(), the post-operation referral function is called after the referral is sent back to the client).
SLAPI_PLUGIN_POST_RESULT_FN	Specifies the function called after the Directory Server sends a result code back to the client (for example, when you call slapi_send_ldap_result(), the post-operation result function is called after the result code is sent back to the client).

Registering Pre/Post-Operation Functions

To register your pre-operation and post-operation plug-in functions, you need to write an initialization function and then configure the server to load your plug-in. For details, follow the procedures outlined in Writing Plug-in Initialization Functions and Configuring Plug-ins.

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last updated November 26, 2004