Each command or file-to-file transaction that a user submits results in BDT issuing one or more messages to the user. When there are a large number of users, the message traffic can become heavy. BDT stores these messages on a data set. TQI periodically reads messages from the data set and routes them to the user. This method of storing and routing messages eliminates a potential burden on virtual storage by eliminating the need to store BDT messages there.