USER queues are permanent, service-controlled message queues. A USER queue is available to every generated UTM user at all times. USER queues can be accessed by any service by means of a program call, provided it knows the name of the user.
By means of this queue, messages can be sent to the user at the terminal, for example, or to a user signed on via a UPIC client. The USER queue is used as a mailbox in this case. The queue can also be used for communication between the dialog service of the user and asynchronous services that run under the same user ID.
In this way, you can, for example, distribute multiprocessor-capable, parallel database information across a number of asynchronous services and “collect” the results in the dialog service.
At generation, read and write protection can be assigned for the USER queue in the KDCDEF statement USER (Q-READ-ACL and Q-WRITE-ACL parameters). You will find more information on the generation of data access control in the openUTM manual “Generating Applications” under the KDCDEF statement USER. Regardless of the data access control in existence, a user can always read messages from and send messages to his or her own user queue.
Time-controlled messages cannot be sent to USER queues.
By means of the KDCS call INIT PU, a program unit can query how many messages there are for the user ID under which it is running.