April 1, 1981 r- I Function I Codel comments I I AUTHORIZE I Control Initializes VMCF for a given virtual machine. I I I UNAUTHORIZE SEND SEND/RECV SENDX RECEIVE CANCEL REPLY QUIESCE RESUME , IDENTIFY I I , REJECT I , .. , Once AUTHORIZE is executed, the virtual I , machine can execute other VMCF subfunctions I , and receive messages or requests from other I I I ,Control I , Data
Data Control Data Control Control Control Control users. I Terminates VMCF activity. I I Directs a message or block of data to another
virtual machine.
Directs a message or block of data to another
virtual machine, and requests notification
of a reply.
Directs data to another virtual machine on a
faster but more restrictive protocol than
the SEND subfunction.
fAllows you to accept selective messages or
data sent via a SEND or SEND/RECV subfunction. Cancels a message or data transfer directed
to another user but not yet accepted by that
Allows you to direct data back to the
originator of a SEND/RECV subfunction,
simUlating full duplex communication.
Temporarily rejects further SEND, SENDX, SEND/RECV, or IDENTIFY requests from other
Resets the status set by the QUIESCE subfunction and allows execution of
subsequent requests from other users.
Notifies another user that your virtual
machine is available for VMCF communication.
Allows you to reject specific SEND or SEND/RECV requests pending for your virtual
machine. flThe word "Data" in this column indicates a data transfer subfunction
, whereas the word "Control" indicates a VMCF control subfunction. L- Figure 14. Virtual Machine Communication Facility (VMCF) Subfunctions 144 IBM VM/370 System Programmer's Guide
Page of GC20-1807-7 As Updated April 1, 1981 by TNL GN25-0829
Using the Virtual Machine Communication Facility
The following discussion presents ideas and suggestions for using the
virtual Machine communication Facility (VKCF). VMCF APPLICATIONS The VM/370 system with VMCF provides the user with the potential to
apply new and different techniques to current applications.
The VMeF functions may be used to multitask virtual machines. Each
virtual machine can become a subtask (parallel or otherwise) of another
virtual machine. A virtual machine task can be a simple program or a
larqe processor. The VMCF functions provide the WAIT/POST, serialization and communication facilities to control such an
environment. The existinq VM/370 functions provide efficient
scheduling, dispatching and basic resource controls. The advantage of
such an environment is that a user is less restricted by operating
system (software) limitations and gains the flexibility of machine
languages and hardware. VMCF provides a clear and concise method for sharing and serializing
resources between virtual machines. The resources can range anywhere
from multi-write minidisks to entire processors. The control functions
for resource sharing (resource management, serialization, and the like)
can be contained in a virtual machine.
It is conceivable that functions could be added to VK/370 without
altering the control program (CP). A special privilege class virtual
machine could be used to provide additional functions to non-privilege
class users using the VMCF interface. Similarly, CMS capabilities could
be expanded (or at least appear to be expanded) by linking CMS with
other virtual machines. The program testing capabilities offered by VMCF can range from device
simulation to teleprocessing network simulation. In particular, VMCF can be used to provide external interactions from one virtual machine to
another. A simulated teleprocessing network could be constructed with
virtual machine. Each virtual machine would effectively become a node
within the network. The network,structure could range from a simple Part 2. Control Program (CP) 145
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