12. Virtual machine X has now completed its communications with virtual machine
Y and issues aSEVER to break the communications path. The SEVER func
tion queues an external interrupt for Y indicating that the communication link
has been broken. Control returns in X at the next instruction after the
SEVER; a return code indicates the path has been broken.
13. The external interrupt queued by step 12 is reflected to Y indicating that the
path has been broken by virtual machine X. Virtual machine Y can now do
any clean up needed in its storage.
14. After virtual machine Y has completed processing, the virtual machine issues aSEVER to notify LUCY that is also is finished with the communication link. LUCY can then clean up the control blocks.
15. When all communications are complete and all communication paths have been
severed, both virtual machines independently invoke the RETRIEVE BUFFER
function.
IUCV Communications Using Parameter List Data
To better understand how data specified in the parameter list is handled, theLUCY functions are covered in a typical user scenario:
1. ThelUCV DECLARE BUFFER, CONNECT, and ACCEPT sequence must
be invoked to establish the user's external interrupt buffer and a path to the
target virtual machine (orCP). If you expect to receive data in the parameter
list, you must authorize such communication on the CONNECT or ACCEPT
by specifying PRMDAT A=YES. The external interrupt information to the
target communicator includes a bit indicating if PRMDAT A=YES was chosen.
2. Issue anLUCY SEND request. When the data is to be passed in the parameter
list, the DAT A=PRMMSG option is used on theLUCY macro, and the
PRMMSG= option is used to move the data into the parameter list.Or you
can avoid using the macro options by initializing the parameter list yourself.
The sender of the message should be prepared to handle a return code indicat
ing that DATA=PRMMSG is not allowed if the target communicator has not
specified PRMDAT A=YES at connection time. A message block (MSGBLOK) is created to represent the message within CP and contains the
message data until presented to the target. The message is queued on the target
send queue.
3. If the target is enabled forIUCV pending-message external interrupts, the tar
get virtual machine receives anLUCY pending-message external interrupt as a
result of theSEND request in the previous step. The message data is stored in
the external interrupt buffer. A flag is set in the IPFLAGS1 field of the buffer
to indicate that the data is in the parameter list. Since the message data has
been presented to the target, the target does not have to issue anIUCV RECEIVE for this message. If the message was a one-way message, the MSGBLOK is destroyed and the communication is complete. There is no
asynchronous return of message completion given to the source (sending) vir
tual machine on a one-way message.
4. If the target is disabled forLUCY pending-message external interrupts and
issues theIUCV DESCRIBE or RECEIVE functions, the message data is
stored in the parameter list. A flag is set in the IPFLAGS 1 field of the parame-
Inter-User Communications Vehicle 125
Y and issues a
tion queues an external interrupt for Y indicating that the communication link
has been broken. Control returns in X at the next instruction after the
SEVER; a return code indicates the path has been broken.
13. The external interrupt queued by step 12 is reflected to Y indicating that the
path has been broken by virtual machine X. Virtual machine Y can now do
any clean up needed in its storage.
14. After virtual machine Y has completed processing, the virtual machine issues a
15. When all communications are complete and all communication paths have been
severed, both virtual machines independently invoke the RETRIEVE BUFFER
function.
IUCV Communications Using Parameter List Data
To better understand how data specified in the parameter list is handled, the
1. The
be invoked to establish the user's external interrupt buffer and a path to the
target virtual machine (or
list, you must authorize such communication on the CONNECT or ACCEPT
by specifying PRMDAT A=
target communicator includes a bit indicating if PRMDAT A=
2. Issue an
list, the DAT A=PRMMSG option is used on the
PRMMSG= option is used to move the data into the parameter list.
can avoid using the macro options by initializing the parameter list yourself.
The sender of the message should be prepared to handle a return code indicat
ing that DATA=PRMMSG is not allowed if the target communicator has not
specified PRMDAT A=
message data until presented to the target. The message is queued on the target
send queue.
3. If the target is enabled for
get virtual machine receives an
result of the
the external interrupt buffer. A flag is set in the IPFLAGS1 field of the buffer
to indicate that the data is in the parameter list. Since the message data has
been presented to the target, the target does not have to issue an
asynchronous return of message completion given to the source (sending) vir
tual machine on a one-way message.
4. If the target is disabled for
issues the
stored in the parameter list. A flag is set in the IPFLAGS 1 field of the parame-
Inter-User Communications Vehicle 125