Network links

Links provide communications between HCL Workload Automation workstations in a network. Links are controlled by the AUTO Link flag, and the Console Manager link and unlink commands. When a link is open, messages are passed between two workstations. When a link is closed, the sending workstation stores messages in a local pobox file and sends them to the destination workstation when the link is reopened.

This means that when links are closed, the message queues fill up with messages for the inaccessible workstations. To maximize the performance of HCL Workload Automation, monitor workstations for closed links and attempt to reopen them as soon as possible.

Note: Extended agents do not have links. They communicate with their domain managers through their hosts.

To have a workstation link opened automatically, turn on the AUTO Link flag in the workstation's definition. The link is first opened when HCL Workload Automation is started on the Master Domain workstation. If the subdomain manager and workstations are not initialized and their AUTO Link flag is on, the master domain manager attempts to link to its subordinates and begin the initialization processes. If the AUTO Link flag is turned off, the workstation is only initialized by running a link command from the master domain manager. After the workstation is initialized, it automatically starts and issues a link back to its domain manager.

If you stop a workstation, the links from it to other workstations are closed. However, the links from the other workstations to it remain open until either one of the following situations occurs:
  • The stopped workstation is restarted and a link command is issued
  • The other workstations' mailman processes time out, and perform an unlink for the workstation

When the link command is issued and the connection has been established, if the domain manager does not receive any reply within the timeout period, the chkhltst service is automatically invoked by mailman.

This service verifies that the workstation mailbox can be successfully read, and checks if there are errors in the mailbox header. Resulting information is logged in the TWSMERGE.log file of the domain manager as follows:
  • If a file system error occurs while opening the mailbox, the following message is reported: AWSBDY126E An error occurred opening the Mailbox.msg file in CPU_NAME.
  • If an error occurs while opening the mailbox because mailman is reading the mailbox, the following message is reported: AWSBDY123I The Mailbox.msg file in CPU_NAME is correctly read by Mailman.
  • If the mailbox is correctly opened, but an error occurs while reading the header, the following message is reported: AWSBDY125E An error occurred reading the header of the Mailbox.msg file in CPU_NAME.
  • If the mailbox is correctly opened and no error occurs while reading the header, the following message is reported: AWSBDY124W The Mailbox.msg file in CPU_NAME is not read by Mailman.

This service can also be launched manually by using the conman command. See the HCL Workload Automation User's Guide and Reference for more details.

To be certain that inter-workstation communication is correctly restored, you can issue a link command after restarting a workstation.