HP-UX SNAplus2 CPI-C Programmer's Guide (June 2003)

CPI-C Calls
Request_To_Send (cmrts)
Chapter 3216
Usage Notes
The request-to-send notification is received by the partner program
through the request_to_send_received parameter of the following
calls:
• Confirmed
• Receive
• Send_Data
• Send_Error
• Test_Request_to_Send_Received
Request-to-send notification is sent to the partner program immediately;
CPI-C does not wait until the send buffer fills up or is flushed.
Consequently, the request-to-send notification may arrive out of
sequence. For example, if the local program is in Send state and issues
the Prepare_To_Receive call followed by the Request_To_Send call, the
partner program, in Receive state, may receive the request-to-send
notification before it receives the send notification. For this reason, the
request-to-send notification can be reported to a program through the
Receive call.
Upon receiving a request-to-send notification, the partner LU retains the
notification until the partner program issues a call that returns the
parameter request_to_send_received . The LU retains only one
request-to-send notification per conversation, so the partner program
may not be notified of every Request_To_Send issued by the local
program.