Open Client Client-Library/C Reference Manual

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Open Client Client-Library/C Reference Manual

Chapter 2 Topics

Callbacks

Notification callbacks

Defining a notification callback

A notification callback is defined as follows:

CS_RETCODE CS_PUBLIC 
 notification_cb(conn, proc_name, namelen)
 
 CS_CONNECTION    *conn;
 CS_CHAR                  *proc_name;
 CS_INT                       namelen;

where:

connection is a pointer to the CS_CONNECTION structure receiving the notification. This CS_CONNECTION is the parent connection of the CS_COMMAND that sent the request to be notified.
proc_name is a pointer to the name of the registered procedure that has been executed.
namelen is the length, in bytes, of *proc_name.

A notification callback must return CS_SUCCEED.

Table 2-5 lists the Client-Library routines that a notification callback calls:

Routines that a notification callback can call
Callable routine	Permitted use
ct_config	To retrieve information only.
ct_con_props	To retrieve information or to set the CS_USERDATA property only.
ct_cmd_props	To retrieve information only. The CS_USERDATA property can be set on command structures allocated with ct_cmd_alloc. The CS_USERDATA property cannot be set on the command structure obtained by the callback's ct_con_props(CS_NOTIF_CMD) call.
ct_cancel(CS_CANCEL_ATTN)	Any circumstances.
ct_bind, ct_describe, ct_fetch, ct_get_data, ct_res_info(CS_NUMDATA)	To retrieve the notification parameter values. The routines must be called with the command structure returned by the callback's ct_con_props(CS_NOTIF_CMD) call.


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