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The sink machine can issue error messages. In addition, you can query the sink machine to generate a list of users on the sink machine.
If the sink machine encounters a problem in processing your FOCUS request, it sends you an error message. The most common problem is that the sink machine is not active. This can happen because:
When you send a request or transaction to a sink machine that is not operating, you receive the FOC542 message, which signals a failure to connect to the sink machine. This could happen if you did not specify the correct sink user ID in your USE command or if the sink machine was never started.
You may also receive FOC541 message if there was an error in your communication with the sink machine.
If the sink machine is shut down normally while you are in the middle of executing a MODIFY or Maintain request, all of your transactions are written to the database. If the sink machine abends (for example, someone entered HX to shut down the sink machine), some of your last transactions may be lost (to minimize these losses, see Protecting Sink Transactions).
If you use an alternate Master File on the sink and the READ keyword is not included in the USE list, the following error message is issued:
(FOC896) READ OPTION REQUIRED ON USE STATEMENT WITH AS AND ON OPTIONS
Note: FOCUS Error Messages contains a complete list of error messages.
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You can display a list of the active source machine user IDs and the file IDs of the sink machine databases from your source machine. The syntax is:
? SU userid
where:
For example, to inquire about the sink machine MULTID, issue the following:
? SU MULTID
The output shows that user ID JBP is now accessing file CAR FOCUS on the A disk of MULTID. The Q in the QUEUE column indicates that user ID JBP is awaiting requests and transactions to be processed:
If no one is using centrally controlled databases on MULTID, the following message displays:
There Are No Users Connected to Server MULTID
If the sink machine is not operating on MULTID, error message FOC542 displays, as described in Error Messages.
The ? SU query may be used to provide test values in FOCEXEC procedures. When ? SU is executed, the query results determine the value stored in the status return variable of Dialogue Manager (&RETCODE). Query results and their corresponding values are:
Query Result |
&RETCODE Value |
Users are active on the sink machine. |
0 |
No users are active on the sink machine. |
8 |
The sink machine is not running. |
16 |
You can later test the &RETCODE value in a -IF command. For example, this procedure tests whether the sink machine is available before starting your MODIFY or Maintain procedure:
? SU sinkid
-RUN
-IF &RETCODE EQ 16 GOTO BAD;
-INCLUDE myproc
-BAD
-EXIT
where:
If the value of &RETCODE is 0 or 8, your specified MODIFY or Maintain procedure will be executed.
You can issue the query without specifying a sink user ID if you issue it from the sink machine user ID:
? SU
or
? USERS
The output is similar to the following:
This is a convenient facility for monitoring user activities.
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