Lucent Technologies Inc.

At+t Corp.

Alex Kononov

Michael Rabinovich

Narain H Gehani

Paul C Ross

William Wayne Plumlee

S David Roth

A method and apparatus for maintaining consistency in databases among data processors of a computer network involves an improved epidemic protocol involving the generation of database version vectors for database replicas. Overhead of the protocol grows linearly with the number of data items being copied during an update propagation, not with the number of data items as in typical epidemic protocols. Since this number is less than the total number of data items in the database, the present protocol promises significant reduction in overhead. A log record is generated including at least the name of the updated data item. The log record has an associated time stamp for the updated data item name in one embodiment or an associated version vector value in another. In the event of out-of-bound copying, an auxiliary log record is maintained.

Maintaining consistency of database replicas

A token-based protocol used to prevent conflicts between copies of the same data items residing in different servers of a replicated distributed system is provided. The servers in the system with database replicas are provided with token pointers that are each associated with a token. Token pointers are used to track the current possessor of the token. Whenever a server receives or transfers a token, its corresponding token pointer is updated to reflect which server possesses the token. The use of token pointers advantageously eliminates the need for global cooperation by the servers to regenerate a lost token.

Preventing conflicts in distributed systems

A replication protocol which includes associating a database version vector with each copy of the database in the system is provided. Each database version vector keeps track of the total number of updates to any data items in its respective database replica and from which server those updates were originally performed. During replication between two replicas, the database version vectors of the replicas are compared to efficiently determine if update replication is necessary. If the database version vectors are not identical, the server possessing the more recent version of the data items propagates those data items to the server whose replica is older using conventional update propagation techniques. Identical database version vectors indicate that update propagation is not necessary. As such, the protocol avoids examining every data item in the database in order to determine the necessity of update propagation, which is required in conventional replication protocols.

Acoustic surveillance of objects and human traffic in spatial zones of a shopping mall and associated retail selling space is used to detect shopper traffic movement and from it, traffic data such as: shopper volume, shopper flow, crowding, and also unusual motion such as crowd surges that might connote an emergency situation. The apparatus uses phased arrays of acoustic transducers including arrays oriented in a vertical aspect which enables differentiation of non-shopping young children to arrive at more accurate headcount figures. Several specific types of detected movement defined as abnormal trigger an alert to a remote monitoring station. The alerts are automatically prioritized using rule-based criteria. Enhanced surveillance of the alert site by audio links as well as site alert history information are also provided.

Acoustically monitored shopper traffic surveillance and security system

Acoustic surveillance of objects and human traffic in a spatial zone of a financial transaction device is used to detect movement within the zone. Several specific types of detected movement defined as abnormal trigger an alert to a remote monitoring station. The alerts are automatically prioritized using rule-based criteria. Enhanced surveillance of the alert site by audio links as well as site alert history information are provided.

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Bridgewater, NJ, United States of America

Alex Kononov