SNAX/HLS Configuration and Control Manual

Step 5. Planning for Programming Standards
Planning the SNAX/HLS Environment
2–28 104705 Tandem Computers Incorporated
DT^SIGNAL ->
.
. ! We have received an SIG message. Most frequently
. ! this results from an ATTENTION key on a terminal
. ! to signal that the partner wants to send data.
. ! This use of the SIG message is restricted to
. ! half-duplex protocols.
. ! The SIG message has 4 bytes (two integers)
. ! of data. The ATTENTION event is signalled by the
. ! value %H0001 in the first two bytes.
. !
. ! Other codes are detected here,
. ! but we won't go into detail.
. !
. ! We assume here that logical data flow is
. ! controlled by flags similar to the following.
.
. IF RECEIVE^DATA^REPLY.USER^DATA^S = [0,1]
. THEN
. TIME^TO^RECEIVE := TRUE
. ELSE
. CALL PROCESS^OTHER^SIGS;
.
DT^REQUEST^CLOSE ->
.
. ! Session partner is demanding a session shutdown.
. ! This can happen only if we are the PLU.
. ! The only acceptable action is to close the session.
. ! We assume that the control of session shutdown is under
. ! control of a flag similar to the one shown below.
.
. TIME^TO^CLOSE^SESSION := TRUE;
DT^MESSAGE^CANCELLED ->
.
. ! The session partner canceled the message. This
. ! section of code can only be reached if LMO is in effect.
. ! Processing of this message is application-specific. The
. ! main point here is to "back out" parts of the message
. ! previously received, or to stop sending the current LMO
. ! message.
.
. CALL PROCESS^MESSAGE^CANCEL;
.
DT^BIND^CINIT^DATA ->
.
. ! This message occurs at session startup, and only when
. ! the WANT^BIND^DATA attribute is set in the PROFILE. It
. ! contains a copy of the user data appended to
. ! the BIND or CINIT messages.