International Business Machines Corporation

Daniel Charles Sturman

Robert Evan Strom

Tushar Deepak Chandra

Michael James Ward

Kevan Lee Miller

Sumeer K Bhola

Yuanyuan Zhao

Marc Adam Kaplan

Guruduth Somasekhara Banavar

Mark C Astley

Kelly Anne Shaw

Colin James Parris

Nayeem Islam

Qixiang Sun

Guruduth Somesekhara Banavar

Wei Tao

Improved access control techniques for distributed messaging systems such as content-based publish/subscribe systems are disclosed. For example, a method for providing access control in a content-based publish/subscribe system, wherein messages are delivered from publishing clients to subscribing clients via a plurality of brokers, includes the following steps/operations. One or more changes to an access control policy are specified. An access control version identifier is associated to the one or more changes. The one or more changes are sent to one or more brokers of the plurality of brokers that have a publishing client or a subscribing client associated therewith that is affected by the one or more changes. The access control version identifier associated with the one or more changes is sent to each of the plurality of brokers.

Dynamic access control in a content-based publish/subscribe system with delivery guarantees

The present invention is directed to a publish/subscribe system containing a plurality of brokers, a plurality of subscribers and plurality of brokers including publisher connecting brokers, intermediate brokers and subscriber connecting brokers. Subscriptions are introduced into the system by the subscribers through associated subscription brokers. New subscriptions are aggregated, assigned a virtual start time and propagated through the system toward the publishers. Each broker maintains subscription information in the form of a directed acyclic graph and a broker vector. Messages are published through the system by the publishers through their associated publisher connecting brokers. Each message is assigned a message vector associating subscriptions to that message. The published messages are routed through the brokers toward the subscribers in accordance with comparisons of message brokers and vector brokers conducted at each broker.

Subscription propagation in a high performance highly available content-based publish/subscribe system

A publish/subscribe system is non-disruptively reconfigured, such that messages are not lost during the reconfiguration. After reconfiguration is initiated, messages that are to be delivered within the publish/subscribe system are forwarded using either an old path or a new path. That is, until the reconfigured system is stabilized, some messages may be delivered using the old path, while other messages are delivered using a new path. After the system is stabilized, the new path is used for delivery of all the messages, until another reconfiguration is initiated.

Non-disruptive reconfiguration of a publish/subscribe system

A technique for reliably multicasting a message within a router network is provided. At least one special router in the network has associated persistent storage for logging a message being routed to one or more clients. When a message is received at this logger node, the logger places the message in persistent storage and sends a logging acknowledgment back to those routers to which the message was originally routed, as well as back towards the source of the message. The logger acknowledgment includes the message id, the logger id, and a logging number. When the logger acknowledgment is received by a router, it looks up the routing information from the original message, and sends the acknowledgment to those neighboring routers to which the original message was sent, excluding the link from which the logger acknowledgment was received. If the original message corresponding to the logger acknowledgment was buffered at this router waiting to be delivered, the message is then delivered to its client nodes. Processes for recovering from node or link failure within the router network, and for at most once delivery of messages, at least once delivery of messages, and exactly once delivery of messages are also provided.

Message logging for reliable multicasting across a routing network

Techniques for arranging operations performable on information in an information processing system are provided. In a system having a plurality of information producers and a plurality of information subscribers, paths are identified over which information traverses, and within which the information is subject to select and/or transform operations. The present invention optimizes the system by reorganizing the sequence of select and transform operations so that transforms follow select operations; and by combining multiple select and transform operations into single select and transform operations, respectively. Using these optimizations, the processing resources of the system can be reorganized, and/or information flow graphs describing the system can be designed, so that the select operations are 'pushed' toward the producers, and transform operations are 'pushed' toward the subscribers. Efficient content-based routing systems can then be used to implement the select operations.

Reduction and optiminization of operational query expressions applied to information spaces between nodes in a publish/subscribe system

A group-based multicast messaging system implementing dedicated logger member for logging all multicast messages sent in the system, and a reliable recovery method for missing messages. The reliable recovery method includes soliciting retransmissions of fresh missing messages to other group members and soliciting of retransmissions of stale missing messages to logger members of the group. One of the loggers or other group members repairs the missing message to thereby ensure reliable delivery of messages in the multicast messaging system. The soliciting of retransmissions makes use of negative gossips for fresh missing messages in the system, with the system implementing a mechanism for propagating the latest state information of members to enable garbage collection of archived messages at logging servers in the system. Further, employed is a selective hashing technique to further reduce control traffic and a relaxed group membership protocol for tracking multicast group membership.

Gossip-based reliable multicast message recovery system and method

Reconfiguration of a continuously available routing network of a publish/subscribe system is achieved by quiescing data messages and control messages within the routing network to preserve first-in first-out ordering thereof, and then, reconfiguring the quiesced routing network. This reconfiguration technique is particularly applicable to a routing network having at least one special node comprising one of a logger node or a sequencer node, wherein the logger node is used to store a message to persistent storage within the routing network prior to delivery of the message to one or more clients, and the sequencer sequences a message with other messages received by the network prior to delivery thereof for ordered delivery of the messages to one or more clients of the network.

Quiescent reconfiguration of a routing network

A scalable merge technique for information retrieval across a distributed network is provided, as well as a fault tolerant technique for communicating information across the distributed network. The merge technique includes multicasting a query request across a spanning tree of the distributed network from a root node to multiple clients of the tree, and receiving back at the root node, a merged response produced from responses from at least some of the clients of the spanning tree. The fault tolerant technique for communicating information across the distributed network includes assigning a unique identifier to each query request, automatically reconfiguring the network upon detection of a failure of a node of the network, and retransmitting the query request and/or any responses thereto within the reconfigured network.

Scalable merge technique for information retrieval across a distributed network

A technique for reliably multicasting a message within a router network in a sequenced order with other messages is provided. At least one special router in the network has associated persistent storage for sequencing a message being routed to one or more clients. When a message is received at this sequencer node, the sequencer places a sequence number for the message in persistent storage and sends a sequencing acknowledgment back to those routers to which the message was originally routed, as well as back towards the source of the message. The sequencer acknowledgment includes the message id, and the sequencing number. When the sequencer acknowledgment is received by a router, it looks up the routing information from the original message, and sends the acknowledgment to those neighboring routers to which the original message was sent, excluding the link from which the sequencer acknowledgment was received. If the original message corresponding to the sequencer acknowledgment was buffered at this router waiting to be delivered, the message is then delivered to its client nodes.

Message sequencing for ordered multicasting of a message across a routing network

A facility is provided for distributing events to consumers in a content-based publish-subscribe system, wherein the consumers each have at least one subscription. The facility includes deriving a set of g approximate multicast groups from a larger set of G possible multicast groups in the publish-subscribe system. The deriving includes exploiting knowledge of subscription predicates of the consumers of the publish-subscribe system. The set of G possible multicast groups is collapsed to the smaller set of g approximate multicast groups, while minimizing the expected performance penalty in using the approximate multicast groups. The set of g approximate multicast groups is then used to forward events to consumers within the publish-subscribe system.

Method and system for matching consumers to events employing content-based multicast routing using approximate groups

Techniques for arranging operations performable on information in an information processing system are provided. In a system having a plurality of information producers and a plurality of information subscribers, paths are identified over which information traverses, and within which the information is subject to select and/or transform operations. The present invention optimizes the system by reorganizing the sequence of select and transform operations so that transforms follow select operations; and by combining multiple select and transform operations into single select and transform operations, respectively. Using these optimizations, the processing resources of the system can be reorganized, and/or information flow graphs describing the system can be designed, so that the select operations are &ldquo;pushed&rdquo; toward the producers, and transform operations are &ldquo;pushed&rdquo; toward the subscribers. Efficient content-based routing systems can then be used to implement the select operations.

Reduction and optimization of information processing systems

A technique for optimizing published event message sequences destined for information subscribers in an information processing system. Subscribers specify event interpretation rules which map event message streams into states. The event interpretation rules are maintained elsewhere in the system in preparation for providing optimized, possibly shorter, event message streams to subscribers, sufficient to correctly update the states. If a subscriber temporarily loses access to its event message stream, the optimized event message stream is determined using a shortest path graph search technique between the states defined by the start and end of the missing portion of the stream. Optimizations to the shortest path graph search technique are disclosed for use when the event interpretation rule is in replacement form, in which estimator functions based on extended rules are employed.

Method and apparatus for summarizing missing events using event stream interpretation

A generalized search data structure is used to match consumers to events in event computing systems. The search data structure includes one or more paths from a root of the structure to one or more leaves of the structure. Each path has at least one level and each level corresponds to a filter attribute. The value of at least one filter attribute in at least one path is a don't care value indicating traversal of that path is guaranteed to proceed. In addition to following the path with the don't care value, one or more additional paths may also be followed. Thus, traversal of the search data structure may yield zero or more results, indicating that zero or more consumers match the specified event. Various optimizations of the search data structure are possible.

Method and system for matching consumers to events

A router within a network uses the data of a message received at the router to determine on which links out of the router the message needs to be forwarded. The router does not need any destination information from the message, and thus, the message need not include any destination information. Instead, the router uses an annotated search data structure to determine which links correspond to consumers interested in receiving the message. The message is sent only over those links.

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Englewood, NJ, United States of America

Daniel Charles Sturman