Abstract: Access to groups of related items which are accessible by multiple processes in a computer system is controlled, in response to determining that an individually accessed data item is part of a group, by marking the whole group as locked and returning an unlocking key to the process accessing the original data item. Further access to any items of the group by a process is prevented except on provision of the key. The invention is particularly applicable to messages in a message queuing system which are logically grouped and yet may be individually destructively retrieved.

Abstract: A data processing apparatus runs a messaging and queuing software package whereby messages received at the data processing apparatus are stored in a message queue. The apparatus has: a processor; a high storage capacity storage device; and a low storage capacity storage device (e.g., a high-speed cache); the high storage capacity storage device stores full-length expiration data for each message in the message queue; and the low storage capacity storage device stores an abbreviated version of the full-length expiration data for each message in the message queue, the abbreviated version used to quickly and efficiently determine whether a queued message is expired.