Abstract: A controller for controlling the processing of a data stream by a data stream processing system having a plurality of data stream management systems, DSMSs. Each DSMS is arranged to execute a respective continuous query to generate an output data stream having continuous query execution results. The controller controls the execution of the continuous query on a windowed portion of a data stream when different DSMSs receive different parts of the data for the windowed portion. The controller selects, for processing of the windowed portion of the data stream, a single DSMS that is to execute the respective continuous query. The controller generates a control signal to cause only the selected DSMS to execute the continuous query using data in the data stream received thereby, so that the continuous query is executed on data in the windowed portion of the data stream only by the selected DSMS.

Abstract: A data stream management system (DSMS) receives an input data stream from data stream sources and respective location information associated with sets of the data stream sources. A continuous query is executed against data items received via the input data streams to generate at least one client output data stream. A load shedding process is executed when the DSMS is overloaded with data from the input data streams. When the DSMS is not overloaded and for the location information associated with each of the data stream source sets, a respective utility value is determined indicating a utility to the client of data from the data stream source sets. The location information is stored in association with the corresponding data utility value. The location information received when the DSMS is overloaded is used, together with the data utility values, to identify input data streams whose data items are to be discarded.

Abstract: There is provided a communication system (100) comprising: a first network node (200) that transmits a flow of data records to a second network node (300) via a network (500), the second network node having a data record processing module (600) that receives and processes the data records; and a controller (700) for controlling the transmission of data records by the first network node.

Abstract: A method of generating a query plan for accessing a database, comprising: receiving (S10) one or more electronic queries from a database client; and determining (S20) whether the received one or more queries form a part of a query pattern comprising a repeating sequence of a plurality of queries by determining whether the received one or more queries match a part of the sequence of queries. If the received one or more queries are determined to form a part of the query pattern, the method further comprises generating (S30) a query plan for executing one or more queries in the sequence that match the received one or more queries, and a query that is subsequent to the matching one or more queries in the sequence.

Abstract: A controller for controlling the processing of a data stream by a data stream processing system having a plurality of data stream management systems, DSMSs. Each DSMS is arranged to execute a respective continuous query to generate an output data stream having continuous query execution results. The controller controls the execution of the continuous query on a windowed portion of a data stream when different DSMSs receive different parts of the data for the windowed portion. The controller selects, for processing of the windowed portion of the data stream, a single DSMS that is to execute the respective continuous query. The controller generates a control signal to cause only the selected DSMS to execute the continuous query using data in the data stream received thereby, so that the continuous query is executed on data in the windowed portion of the data stream only by the selected DSMS.

Abstract: A data stream management system (DSMS) receives an input data stream from data stream sources and respective location information associated with sets of the data stream sources. A continuous query is executed against data items received via the input data streams to generate at least one client output data stream. A load shedding process is executed when the DSMS is overloaded with data from the input data streams. When the DSMS is not overloaded and for the location information associated with each of the data stream source sets, a respective utility value is determined indicating a utility to the client of data from the data stream source sets. The location information is stored in association with the corresponding data utility value. The location information received when the DSMS is overloaded is used, together with the data utility values, to identify input data streams whose data items are to be discarded.

Abstract: A continuous query result estimator for use in a data stream management system. The data stream management system configured to execute a continuous query against data items received via at least one input data stream to generate at least one output data stream. The continuous query result estimator comprises a classification module configured to classify a set of at least one data item received via the at least one input data stream into one of a plurality of input data groups. A data store configured to store a respective rule for estimating a result of executing the continuous query against a data item belonging to the input data group. The continuous query result estimator also includes a result estimation module configured to select a rule from the rules stored in the data store on the basis of the classification performed by the classification module.

Abstract: Apparatus for performing packet classification of data packets belonging to a packet flow through a packet data network. The apparatus comprises an ingress interface for receiving packets of said packet flow, and an active filter for disturbing one or more of said packets or for otherwise disturbing a characteristic of said flow. An egress interface is provided for sending the packets including a disturbance towards a destination. A monitor is also provided for monitoring said packet flow and/or one or more associated packet flows received by the apparatus to detect subsequent reactions in the flow/s to the disturbance, while a flow classifier is provided for attempting to classify the flow into one of a set of defined classes according to a detected reaction.

Abstract: A continuous query result estimator for use in a data stream management system. The data stream management system configured to execute a continuous query against data items received via at least one input data stream to generate at least one output data stream. The continuous query result estimator comprises a classification module configured to classify a set of at least one data item received via the at least one input data stream into one of a plurality of input data group. A data store configured to store a respective rule for estimating a result of executing the continuous query against a data item belonging to the input data group. The continuous query result estimator also includes a result estimation module configured to select a rule from the rules stored in the data store on the basis of the classification performed by the classification module.

Abstract: A method of generating a query plan for accessing a database, comprising: receiving (S10) one or more electronic queries from a database client; and determining (S20) whether the received one or more queries form a part of a query pattern comprising a repeating sequence of a plurality of queries by determining whether the received one or more queries match a part of the sequence of queries. If the received one or more queries are determined to form a part of the query pattern, the method further comprises generating (S30) a query plan for executing one or more queries in the sequence that match the received one or more queries, and a query that is subsequent to the matching one or more queries in the sequence.

Abstract: Apparatus for performing packet classification of data packets belonging to a packet flow through a packet data network. The apparatus comprises an ingress interface for receiving packets of said packet flow, and an active filter for disturbing one or more of said packets or for otherwise disturbing a characteristic of said flow. An egress interface is provided for sending the packets including a disturbance towards a destination. A monitor is also provided for monitoring said packet flow and/or one or more associated packet flows received by the apparatus to detect subsequent reactions in the flow/s to the disturbance, whilst a flow classifier is provided for attempting to classify the flow into one of a set of defined classes according to a detected reaction.

Abstract: A data scheme and protocol (DSP) adapter which translates communications received from one or more application servers (FEs) into corresponding communications understandable by one or more repositories (BEs). The DSP adapter comprises an interface unit which receives a FE query from a FE. The DSP adapter comprises a processing unit which determines an FE query pattern fulfilled by the FE query and checks whether the FE query pattern exists for the FE query in an accessible memory. Where the FE query pattern does not exist in the accessible memory, the processing unit transforms the FE query pattern into a corresponding BE query pattern. Where the FE query pattern exists in the accessible memory, the processing unit obtains the corresponding BE query pattern from the accessible memory. A method for translating at a data scheme and protocol (DSP) adapter communications received from one or more application servers (FEs) into corresponding communications understandable by one or more repositories (BEs).