Only application programs created for reception can receive message log notification. OpenTP1 UAPs (SUPs, SPPs, and MHPs) cannot receive a message log notification.

When receiving a notification, the application program uses OpenTP1 functions. When writing an application program, include the header file of the OpenTP1 log service and link the OpenTP1 library.

For an application program to receive a notification, the environment variable DCDIR that identifies the OpenTP1 home directory must be set. The value assigned to this environment variable must be the same as for the OpenTP1 that will send the message log notification.

If you need all message logs generated since OpenTP1 online operation started, the application program to receive notifications must be started before the OpenTP1.

The application program to receive notifications must declare the starting of reception using the function dc_log_notify_open(). It receives message logs using the function dc_log_notify_receive(). Only one message log can be received by one run of the function dc_log_notify_receive(). To receive multiple message logs, repeatedly invoke the function dc_log_notify_receive().

To terminate receiving message log notifications, invoke the function dc_log_notify_close(). Even after invoking the function dc_log_notify_close(), you can restart receiving message log notifications by invoking the function dc_log_notify_open().

Even after the OpenTP1 terminates, the notification reception application program continues to wait until the function dc_log_notify_close() is invoked. To notify a waiting application program of reception completion, send data from another application program using the function dc_log_notify_send(). The application program for reception completion notification cannot invoke the function dc_log_notify_open() before invoking the function dc_log_notify_send().

The figure below shows the reception of a message log notification.

Figure 2-55 Reception of message log notification

Notes on receiving message log notifications are given below.

• The functions dc_log_notify_open(), dc_log_notify_receive(), dc_log_notify_close(), and dc_log_notify_send() cannot be executed from within an interrupt routine.
• Message log notifications may or may not be received from the OpenTP1 depending on the time the function dc_log_notify_receive() is invoked. The following message logs cannot be received:
  
  1. Message logs output by the OpenTP1 when the application program is inactive, before the application program invokes the function dc_log_notify_open(), or after the application program invokes the function dc_log_notify_close()
  2. Message logs that come after the message log receive buffer has run short of space because the function dc_log_notify_receive() was not invoked when a previous message log was reported by the OpenTP1