SNAX/HLS Application Programming Manual

RECEIVE DATA Verb
SNAX/HLS Verbs
5–88 104707 Tandem Computers Incorporated
created the session with the HLS–ALLOCATE and HLS–OPEN
verbs.
It is highly unlikely that your application needs to know the precise
reason that the session was closed, but , if it does, the data reply area
contains the actual SNA message unit that caused the closure. For
example, if the closure occurred because the session partner issued a
normal UNBIND command (this can happen only if you are
secondary), you receive a 2–byte message containing the value
%H3201.
10 (Name is DT–FLOW–CONTROL.) This occurs only if the receipt of flow
control messages has been enabled for the receiving half–session.
Such messages are enabled based upon the
WANT–FLOW–CONTROL attribute in the PROFILE, or by the
issuance of the SM (Stop Messages) request. It indicates that one of
the four supported flow control signals has been received. The
specific signal is indicated by the contents of the data field, which
contain two characters, as follows:
RT (SNA RTR message.) This message was sent by the session
partner to invite you to begin new transactions. You need not
actually honor the request. However, it could be used to cause
your application to retry sending an old transaction that was
rejected with an %H0813 or %H0814 sense code.
SM (SNA QEC message.) This message was sent by your partner
to request that you stop sending new messages. This is
frequently used because the session partner is temporarily
congested. If you are using LMO and have begun a message,
you can send the remainder of the message (up to and
including the element that carries the MESSAGE–COMPLETE–
IND set to Y). Once the end of the current message has been
sent, or if you are not using
LARGE–MESSAGE–OPTION, no more data traffic is accepted.
The only acceptable action at this point, other than session
termination, is to issue the HLS–FLOW–CONTROL verb
using QM as the argument.
QM (SNA QC message.) This message was sent by the session
partner in response to an HLS–FLOW–CONTROL verb using
SM that you sent. It confirms that your partner sends no more
messages until you send the resume signal,
HLS–FLOW–CONTROL(RM).
RM (SNA RELQ message.) This message was sent by the session
partner to indicate that message traffic can resume. It most
frequently is used after traffic was stopped by previously
issued QEC and QC messages, or after the sessions have
exchanged PREPARE–TO–CLOSE messages.