APPC/VM Interrupts

In APPC/VM, your program may receive notification of pending functions through external interrupts. Interrupts are caused by actions taken by the virtual machine on the other end of the local APPC/VM path. Interrupts indicate pending and completed functions. For example, your virtual machine receives an interrupt when another virtual machine sends you a message that it wants you to receive.

At the start of your program, you should create a buffer to hold the interrupt information for an established APPC/VM path. (You can create this buffer using the HNDIUCV SET or IUCV DCLBFR function.) This buffer is a 40-byte area called an external interrupt buffer. There are two types of external interrupt buffers, control and application. For a complete description of these buffers, see the section on the IUCV DCLBFR (Declare Buffer) function in the z/VM: CP Programming Services. When your program is presented with an interrupt, information about the interrupt goes into one of these external interrupt buffers.

The possible APPC/VM interrupts you can get fall into two categories. The first type of interrupt signals that your communications partner has invoked some function, independent of your actions. These interrupts are:
  • Connection pending
  • Message pending
  • Request-to-Send
  • Sever.
The second type of interrupt signals the completion of a function that you initiated. These interrupts are:
  • Connection complete
  • Function complete.

The six basic types of APPC/VM interrupts are described in the following paragraphs.