Chapter 10 Writing Entry Store/Fetch Plug-Ins

This chapter describes how to write entry store and entry fetch plug-ins. You can use these types of plug-ins to invoke functions before and after data is read from the default database.

Note. Entry store and entry fetch plug-ins work only with the default database. If you are using your own database and have your own database plug-in, entry store and entry fetch plug-ins will not work.

Figure 10.1 illustrates how the Directory Server back-end calls entry store and entry fetch functions before writing and reading data from the database.

Figure 10.1 How the server calls entry store and entry fetch plug-in functions

Instead, entry store and entry fetch plug-in functions must have the following prototype:

void function_name( char **entry, unsigned long *len );

On Windows NT, use the following prototype and make sure to include the function in a .def file:

__declspec( dllexport ) void function_name( char **entry, unsigned long *len );

The parameters are described below:

entry	Pointer to a string specifying the entry in LDIF format (for details on this format, see "slapi_entry2str()" on page  268).
len	Pointer to the length of the entry string.

Since the text of the entry is passed in as an argument, you can modify the entry before it gets saved to disk and modify the entry after it is read from disk.

Instead, you specify the function name directly in the slapd.conf configuration file. Add a directive in the following form to specify the name and location of your plug-in function:

plugin entrystore <library_name> <function_name>

plugin entryfetch <library_name> <function_name>

<library_name> is the name and path to your shared library or dynamic link library, and <function_name> is the name of your plug-in function.

For example, the following directives register the function named my_store() as the entry store plug-in function and my_fetch() as the entry fetch plug-in function. Both functions are defined in the library /usr/nslib/myentry.so.

plugin entrystore /usr/nslib/myentry.so my_store

plugin entryfetch /usr/nslib/myentry.so my_fetch

Note. Each entry store and entry fetch plug-in is associated with the default ldbm back-end. Make sure that the plugin directive that registers the plug-in is within the database section for ldbm in the slapd.conf file. (The plugin directive should be after the database ldbm directive and before the next database directive, if any.)