International Business Machines Corporation

John Justin Duigenan

Graham Derek Wallis

Gidon Gershinsky

Boaz Carmeli

Mark E Taylor

Stephen James Todd

Julian Satran

Michael D Elder

Haim Nelken

Michael Damein Elder

A multicast host for communicating information published about any one of a set of topics to one or more authorised subscribers to those topics, the set of topics being partitioned into one or more partition elements, each partition element having a partition element encryption key associated therewith, wherein each of the one or more partition elements is a disjoint proper subset of the set of topics, the host comprising: means for receiving information relating to a topic; means for determining a partition element for the topic; means for retrieving a partition element encryption key associated with the partition element; means for encrypting the information with the retrieved partition element encryption key; and means for communicating the information to the one or more authorised subscribers.

Access control over multicast

A variety of techniques are disclosed for efficient liveness monitoring in a reliable publish/subscribe multicast system having at least one broker and at least one subscriber, by: at the broker, sending () a status request message to the subscriber, and at the subscriber, sending () a status response message to the broker to indicate liveness. Status responses by subscribers may be suppressed when at least a chosen minimum number (&#x3e;=1) of subscribers send a response. This suppression (-) uses a system of 'response claim' messages and random back-off timers. These provide the advantage that the efficiency of network usage is improved by reducing the number of unwanted packets that are sent.

Liveness monitoring in a publish/subscribe messaging system

The invention relates to a message broker for managing subscription requests in a multicast messaging system. The messaging system comprises a plurality of publishers publishing information to the broker and a plurality of subscribers subscribing to information received from one or more publishers. The broker is able to receive a subscription request pointing to topic information in which the requesting subscriber is interested, the topic information defining a specific topic within a topic hierarchy. The broker is able to parse the request to determine if the request includes a wildcard and if the request does include a wildcard, the broker instructs the requesting subscriber to listen on a multicast address associated with the topic in the topic hierarchy which precedes the wildcard.

Publish/subscribe messaging system

A transmission method adjusts the size of aggregated packets based at least on the congestion of a transmitting network device. The adjusting comprises includes aggregating at least two small messages, received from an upper layer, into a packet, providing the packet to a pending queue, passing packets to a network device and selecting packets from the pending queue or the buffer depending on whether or not the pending queue is empty.

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Bournemouth, United Kingdom

John Justin Duigenan