Informix DataBlade API Programmer's Manual DataBlade API Function Descriptions

The mi_retrieve_callback() function retrieves the handle of a registered callback.

mi_integer mi_retrieve_callback(conn, event_type, cback_handle, cback_func,

user_data)

MI_CONNECTION *conn;

MI_EVENT_TYPE event_type;

MI_CALLBACK_HANDLE *cback_handle;

MI_CALLBACK_FUNC *cback_func;

void **user_data;

conn	is either NULL or the connection descriptor that a previous call to mi_open(), mi_server_connect(), or mi_server_reconnect() has established.
event_type	is the type of event that the cback_handle callback handles. For a list of valid event types, see Figure 10-1 on page 10-4.
cback_handle	is the callback handle from a previous call to mi_register_callback().
cback_func	is a pointer to the location at which to return a pointer to the callback function.
user_data	is the user-supplied argument to the callback function.

Valid in Client LIBMI Application?	Valid in User-Defined Routine?
Yes	Yes

The mi_retrieve_callback() function returns a callback-function pointer (MI_CALLBACK_FUNC) when you pass in a callback handle (MI_CALLBACK_HANDLE). This function is useful when a DataBlade API module needs to temporarily change the callback that is registered for a particular event.

For a C UDR, conn must be NULL for the following event types:

• MI_EVENT_END_STMT
• MI_EVENT_END_XACT
• MI_EVENT_END_SESSION

For a client LIBMI application, you must provide a valid connection descriptor to mi_retrieve_callback() for callbacks that handle the following event types:

• MI_Exception
• MI_Xact_State_Change
• MI_Client_Library_Error

See the description of the mi_register_callback() function.

For more information, see Retrieving the Callback Function.