Communicating with VM/CMS Virtual Machines › z/OS to z/VM Client/Server Application › How the Client/Server Pieces Work

How the Client/Server Pieces Work

The following is the normal flow for:

• Server initiated messages to a VM client
  • The server initiated messages are pulled from a message queue identified as a CA OPS/MVS global variable.
  • The message text is formatted and appended to the queue using the provided REXX queue manager program.
  • The server code periodically samples the global variable contents and then activates network traffic as required.
  • The message text normally contains an automation message to CA VM:Operator; however, it can contain commands to the server.
  • The server code transmits through a TCP/IP socket connection, so the client VM ID does not have to be known.
  • In order to deliver to its VM:Operator destination, the client code forwards the message using the CP SMSG facility.
• Client initiated messages to the z/OS server
  • The message text must be delivered to the VM client's ID through the CP SMSG facility.
  • Client code reacts to incoming SMSG on a configurable timer interrupt basis with a one-second minimum value.
  • The text may be a command, which will be handled locally, or text with the z/OS server as its destination, in which case it is delivered to the server facility defined in the startup parameter tailoring.
  • The client response contains the return code of the WTO or GLV update result. The return code for a successful GLV is 1.

In addition to messages exchanged between server and client, there are additional facilities to perform certain command functions on both server and client. These will be discussed later in this chapter.