Patent ID: 8355401

Claim:
A method of controlling access to a device in a data processing network, the method comprising: receiving a first request from a client to connect to a device implemented as a message broker in the data processing network that comprises a messaging system, where the device is limited to a fixed number of client connections, wherein the client is a subscriber to a message on topics published to the message broker; connecting the client to an available client connection of the device if the fixed number of client connections on the device would not be exceeded by connecting the client; testing liveness of a current client connection on the device if the fixed number of client connections on the device would be exceeded by connecting the client; dropping the current client connection if the liveness testing indicates that the current client connection is not live; and storing the message in a repository, wherein: the message matches a durable subscription previously registered in respect of the subscriber; the message persists even when the subscriber is disconnected, and the fixed number of client connections are configured so that only one subscriber is permitted to be associated with one durable subscription at any one time, whereby, in response to failure of the liveness test, the previous registration to the durable subscription is deleted enabling a new subscriber connection to resume the durable subscription.