US 8,428,065 B2Granted

Group communication system achieving efficient total order and state synchronization in a multi-tier environment

AssigneeInternational Business Machines Corporation

InventorsEliezer Dekel, Gidon Gershinsky, Avraham Harpaz, Alexander Krits, Benjamin Mandler, Nir Naaman, Idan Zach

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Abstract

A group communication service maintains synchronization limiting the group to the processing entities that receive a plurality of source message streams from sources outside the group and transmit delivery message streams to destinations that are outside the group. Synchronization of message ordering and other state synchronization directives are communicated from a leader exclusively to other group members. Once having declared themselves to be synchronized and active by a reply protocol message, which is an opaque object and is interpreted by an application layer, the processing entities independently process the source message streams in accordance with the order specified in the directives, without requiring additional sequencing information from another processing entity.

Claims20

Dependent claims

A method for communication, comprising:

arranging a group of servers to receive concurrently incoming multicast messages from multiple message sources outside the group of servers, and to process the incoming multicast messages to produce multiple outgoing streams of outgoing multicast messages for delivery to recipients outside the group of the servers,
wherein at least some of the incoming multicast messages are received at different servers in the group in different respective message orders;
designating one of the servers as a leader;
periodically determining, by the leader, a common message order for processing of the incoming multicast messages by the servers;
periodically transmitting from the leader to the other servers in the group a control message indicative of the common message order determined by the leader, wherein the control message is transmitted with a quality of service (QoS) that is selected so as to ensure consistent delivery of the multicast messages over all the servers in the group;
and
responsively to the control message, processing all the incoming messages at all the servers according to the common message order irrespective of the different orders in which the incoming messages are received and, responsively to the processing, delivering the outgoing multicast messages in the outgoing message streams from the servers to all the recipients.

4 more elements

A computer software product, comprising a tangible non-transitory computer-readable medium in which computer program instructions are stored, which instructions, when read by a group of servers, cause the servers to receive concurrently incoming multicast messages from multiple message sources outside the group of servers, and to process the incoming multicast messages to produce multiple outgoing streams of outgoing multicast messages for delivery to recipients outside the group of the servers,

wherein at least some of the incoming multicast messages are received at different servers in the group in different respective message orders, and
wherein the instructions cause the servers to designate one of the servers as a leader and cause the leader to periodically determine a common message order for processing of the incoming multicast messages by the servers and to periodically transmit to the other servers in the group a control message indicative of the common message order determined by the leader, wherein the control message is transmitted with a quality of service (QoS) that is selected so as to ensure consistent delivery of the multicast messages over all the servers in the group, and
wherein the instructions cause the servers to process, responsively to the control message, all the incoming messages at all the servers according to the common message order irrespective of the different orders in which the incoming messages are received and, responsively to the processing, to deliver the outgoing multicast messages in the outgoing message streams from the servers to all the recipients.

Communication apparatus, comprising plurality of servers, which are arranged in a group and are configured to receive concurrently incoming multicast messages from multiple message sources outside the group of servers, and to process the incoming multicast messages to produce multiple outgoing streams of outgoing multicast messages for delivery to recipients outside the group of the servers,

wherein at least some of the incoming multicast messages are received at different servers in the group in different respective message orders, and
wherein the servers are configured to designate one of the servers as a leader, wherein the leader periodically determines a common message order for processing of the incoming multicast messages by the servers and periodically transmits to the other servers in the group a control message indicative of the common message order determined by the leader, wherein the control message is transmitted with a quality of service (QoS) that is selected so as to ensure consistent delivery of the multicast messages over all the servers in the group, and
wherein the servers are configured to process, responsively to the control message, all the incoming messages at all the servers according to the common message order irrespective of the different orders in which the incoming messages are received and, responsively to the processing, to deliver the outgoing multicast messages in the outgoing message streams from all servers to all the recipients.

Dependencies are inferred from the claim text.