Abstract:
In order to make real time and the avoidance of risk compatible according to the contents of processing by an application, an index ID applying module applies an index computed utilizing streams before and after stream data to the stream data, computes the index again according to a stream that varies every moment, applies an index computed based upon the index of the stream data to the result of the processing of the stream data according to a predetermined procedure and outputs it. An application that receives the result of the processing and the index of the result of the processing switches processing depending upon the index.

Description:
CLAIM OF PRIORITY 
     The present application claims priority from Japanese application JP 2007-169228 filed on Jun. 27, 2007, the content of which is hereby incorporated by reference into this application. 
     FIELD OF THE INVENTION 
     The present invention relates to stream data processing technique, and particularly relates to technique effective in adding reliability to the result of the processing of stream data in a radio frequency identification (RFID) reader and a sensor. 
     BACKGROUND OF THE INVENTION 
     In comparison with a database management system (hereinafter called DBMS) which executes a processing for data store in a storage system, there is an increasing demand for a data processing system which performs real-time processing, in case where the object to be processed is data arriving from moment to moment. 
     For example, as for a store, it is an important subject to utilize a smart shelf system which is a system for grasping the stock of the store in real time by exhibiting products to which each RFID tag is added on a product exhibit shelf on which an RFID reader is installed and continuously reading the RFID tag by the RFID reader and to make good use of a situation of the stock that varies every moment for sales promotion. 
     For such a data processing system which defines data transmitted every moment as stream data and is suitable for the real time processing of the stream data, a stream data processing system is proposed and for this type of stream data processing system, a stream data processing system STREAM is known (for example, refer to “Query Processing, Resource Management, and Approximation in a Data Stream Management System” written by R. Motwani, J. Widom, 22rasu, 21abcock, S. Babu, M. Datar, G. Manku, C. Olston, J. Rosenstein, and R. Varma in Proc. of the 2003 Conf. on Innovative Data Systems Research (CIDR), January (a non-patent document 1)). 
     For example, real time store stock management can be realized as follows by utilizing the stream data processing system in the smart shelf system. The stream data processing system continuously receives store stock information that varies every moment from the smart shelf system. 
     The stream data processing system detects an event that a product is taken out of a shelf by a customer by comparing a store stock situation at each time at which a store stock situation is received and a store stock situation at the preceding time. 
     A terminal for displaying product information such as a display is installed in a position adjacent to a shelf and visible to a customer and when the stream data processing system detects that a product is taken out of the shelf, it displays the explanation of the taken product and its related information. The purchase by the customer of the product can be promoted by displaying when the customer takes the product out of the shelf. 
     As described above, the stream data processing system is suitable for a real time application that utilizes the result of the real time processing of successively input stream data such as data from the RFID reader and the sensor and financial information including a stock price trend. 
     Besides, a demand for processing a data set including data not necessarily correct such as data output from the RFID reader and the sensor, data including noise as a result of the failure of reading and a measurement error and web data registered by the public increases. 
     For this type of processing system, a system TRIO that handles the reliability of data in a relational database (RDB) is known (for example, refer to “Trio-One: Layering Uncertainty and Lineage on Conventional DBMS” written by M. Mutsuzaki, M. Theobald, A. de Keijzer, J. Widom, P. Agrawal, O. Benjelioun, A Das Sarma, R. Murthy, and T. Sugihara in Proceedings of the Third Biennial Conference on Innovative Data Systems Research (CIDR07), January, 2007 (a non-patent document 2)). 
     For example, for the eyewitness report of a traffic accident, information such as reliability that a car which caused an accident is A is 0.6 and reliability that the car is B is 0.4 and information such as reliability that a driver of the car A is “a” is 0.3 and reliability that the driver is “b” is 0.7 are stored in the database. 
     Candidates to which reliability is added of the driver who caused the accident can be acquired by matching the eyewitness report of the car which caused the accident and the eyewitness report of the driver with the database storing such information. 
     As described above, in the TRIO system, reliability-added data is queried and the reliability-added result of the processing can be acquired. 
     For a processing system when no sensor data exists at predetermined time, a system that computes the reliability at that time of sensor data at another time and outputs the sensor data and the reliability is known (for example, refer to JP-A No. 2006-268369). 
     Even if no sensor data exists at predetermined time when a request for the output of sensor data at the predetermined time is made from external equipment, the reliability at the predetermined time of sensor data at another time is computed, and the computed reliability and the sensor data at another time are output. Hereby, the sensor data processing side can handle the sensor data like synchronous data by referring to the reliability. 
     SUMMARY OF THE INVENTION 
     However, it was found by these inventors that the above-mentioned stream data processing technique had the following problems. 
     That is, the technique disclosed in the non-patent document 1 has a problem that an error is propagated in the result of the processing of data including an error such as noise in environment where the data including an error such as noise is continuously transmitted and it cannot be judged whether the result of the processing is erroneous or not. 
     Besides, in the technique disclosed in the non-patent document 2, data the reliability of which varies in real time cannot be efficiently processed. In the meantime, in the technique disclosed in JP-A No. 2006-268369, as reliability cannot be added to input data, the sufficient solution of reducing a risk by processing based upon error data at the same time as the real time processing of input data is not disclosed. 
     For example, read noise is included in data output from the RFID reader and the sensor. Noise is also included in the result of processing based upon the input data. An application that receives the output cannot judge whether the received data is noise or not and erroneous processing may be caused. 
     The smart shelf system will be described as an example below. 
     The smart shelf system is configured by a product exhibition shelf, an RFID reader and an RFID tag. The RFID reader is installed on the product exhibition shelf and the RFID tag is added to a product exhibited on the product exhibition shelf. 
     The RFID reader reads RFID tags at a fixed cycle such as every second and determines that a product to which a readable RFID tag is added exists on the shelf and a product to which an unreadable RFID tag is added is taken out of the shelf by a customer. 
     Depending upon an RFID tag and a characteristic of the RFID reader, the RFID reader may fail to read the RFID tag for a moment. This phenomenon is called fluctuation. The RFID reader may read an RFID tag to be read by an adjacent RFID reader for a moment. Though a product is actually not taken, the product may be regarded as taken out by this phenomenon. 
     When a frequency at which a product is picked up by a customer is totalized based upon RFID tag information read by the RFID reader and analysis such as extracting correlation between the picked-up product and a well-sold product is made, a problem that a product to which an RFID tag where fluctuation is easily caused is added is judged to be picked up plural times though the customer does not actually pick it up and the result of erroneous analysis is output occurs. 
     To avoid the above-mentioned totalization and analysis which do not conform to an actual situation, when data input from the RFID reader and the sensor is processed, a method of considering the reliability of the data is conceivable. 
     The reliability of time series data output from the RFID reader and the sensor can be evaluated in consideration of a characteristic of a measured object. For example, in the above-mentioned example of the smart shelf system, it is hardly conceivable that a customer takes a product out of the product exhibition shelf only for one second and afterward, soon returns it to the product exhibition shelf. 
     Therefore, it is conceivable that in time series data in which the result of the read of an RFID tag by the RFID reader is output, a product has a characteristic that the position is unchanged for a certain extent of long time (for example, for three seconds). 
     As a possibility that data telling that the position is changed only for one second is caused by fluctuation is judged to be high based upon such a characteristic, reliability that a product is taken out of the shelf by a customer is set to a small value. 
     As described above, generally, to acquire the reliability of time series data, data before and after the time series data are required to be used for determination. That is, generally, to acquire the reliability of time series data, the succeeding data is required to be awaited. 
     In the meantime, when the result of processing is output after the reliability is acquired after fixed time (for example, 5 seconds) elapses, processing to be executed at real time is disabled. 
     For example, in the example of the smart shelf system, customer service that product information is displayed on a display installed on the smart shelf in a moment in which a customer takes a product out of the shelf is important in expanding a sales chance. 
     It is important to provide this service in the moment in which the product is taken out and in the display after the fixed time, large effect in expanding a sales change cannot be desired. In the meantime, even if product information is displayed because of fluctuation though a product is actually not taken out of the shelf by a customer, its effect is small. 
     When the stream data processing technique disclosed in the non-patent document 1 and the reliability-added data processing technique disclosed in the non-patent document 2 are combined, data acquired by adding reliability generated based upon the reliability of input reliability-added stream data to stream data to which processing such as totalization is applied can be output, however, as fixed time is required to be awaited to acquire the reliability of the stream data, a problem that real time cannot be secured occurs. 
     As described above, the security of real time and the avoidance of an error risk of the result of processing by noise are related as the relation of a trade-off. 
     An object of the invention is to provide technique that enables the compatibility of real time and the avoidance of a risk and reliable stream data processing according to the contents of processing by an application. 
     The above-mentioned and another objects and new characteristics of the invention will be clarified by the description of this specification and the attached drawings below. 
     The brief description of a representative outline of the invention disclosed in this application is as follows. 
     The invention is based upon a stream data processing system that processes a stream which is a flow of time series data including time stamps-applied plural data continuously incoming in the ascending order of the time stamps according to an arbitrarily registered query, and a stream data processing system according to the invention applies an index to be a first index computed based upon index function algorithm to stream data utilizing a stream in arbitrary time and applies an index to be a second index acquired based upon the index of the first index to the result of the processing of the stream data to which the first index is applied. 
     Besides, an outline of another invention in this application will be briefly described below. 
     The invention is based upon a stream data processing system that processes a stream which is a flow of time series data including time stamps-applied plural data tuples incoming in the ascending order of the time stamps according to an arbitrarily registered query, and a stream data processing system according to the invention is provided with an index ID applying module that computes an index of input stream data as a first index, acquires index ID and outputs the stream data to which the index ID is applied and computes the index at arbitrary time again, an index storing module that stores a set of the acquired index ID, the computed index and time at which the index is computed or a set of the index ID, the recomputed index and time at which the index is recomputed, a processing data management module that manages stream data to which index ID to be a processing object is applied according to a registered query, an index ID-applied data processing module that applies processing to stream data to which index ID to be the processing object is applied at each time and outputs an index ID expression showing the result of the processing and described utilizing the result of the processing and the index ID and an indexed data output module that acquires an index as the result of the processing based upon the index ID expression and the index stored in the index storing module and outputs it together with the result of the processing. 
     Besides, the invention is based upon a stream data processing system that processes a stream which is a flow of time series data including time stamps-applied plural data tuples incoming in the ascending order of the time stamps according to an arbitrarily registered query, and a stream data processing system according to the invention is provided with an index applying module that computes an index to be a first index of input stream data, outputs the stream data to which the index is applied, computes the first index at arbitrary time again and outputs the stream data to which the first index is applied, a processing data management module that manages stream data to which index ID to be a processing object is applied according to an arbitrarily registered query and an indexed data processing module that applies processing to stream data to which the first index to be a processing object is applied at each time and outputs the result of the processing and an index to be a second index. 
     Further, an outline of the other invention in this application will be briefly described below. 
     In a stream data processing method in which a first index that is a result of computing utilizing a stream in a limited range according to a predefined computation expression is applied to stream data and a second index acquired based upon index values of the first index is applied to a result of processing the indexed stream data, the index is equivalent to reliability which is probability showing the validity of stream data. The index may be also similarity to model time series data, probability judged to be a value off time series data before and after the corresponding time series data and probability judged to be a change point based upon the time series data before and after the corresponding time series data except the reliability. 
     As for the index of the result of the processing, as a stream varies every moment, the index of the stream data is computed again when a successive time stamp-applied stream data tuple is incoming or at an arbitrary time interval and an index of the result of processing is computed based upon the recomputed index of stream data. 
     An index of stream data is computed utilizing streams in a limited range before and after stream data according to a predefined computation expression. 
     The brief description of effect acquired by the representative embodiments of the invention disclosed in this application is as follows. 
     Control over execution that realizes an optimum trade-off between real time and reliability in stream data processing is enabled, and the security of real time and the avoidance of an error risk of the result of processing by noise can be compatible. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram showing an example of the configuration of a stream data processing system equivalent to a first embodiment of the invention; 
         FIG. 2  is a flowchart showing an example of processing by an index ID applying module provided to the stream data processing system shown in  FIG. 1 ; 
         FIG. 3  is a flowchart showing an example of processing following the processing shown in  FIG. 2  by the index ID applying module; 
         FIG. 4  is a flowchart showing an example of processing following the processing shown in  FIG. 3  by the index ID applying module; 
         FIG. 5  is a flowchart showing an example of processing by a processing data management module provided to the stream data processing system; 
         FIG. 6  is a flowchart showing an example of processing by an index ID-applied data processing module provided to the stream data processing system; 
         FIG. 7  is a flowchart showing an example of processing by an indexed data generating module and an index ID evaluating module respectively provided to the stream data processing system; 
         FIG. 8  is a flowchart showing an example of processing following the processing shown in  FIG. 7  by the indexed data generating module and the index ID evaluating module; 
         FIG. 9  is a flowchart showing an example of processing by an index store module provided to the stream data processing system; 
         FIG. 10  is an illustration schematically showing one example of a data format of stream data used for the stream data processing system shown in  FIG. 1 ; 
         FIG. 11  is an illustration showing a product position measurement stream including continuously input stream data; 
         FIG. 12  is an illustration schematically showing an example of data stored by a reference data store management module provided to the stream data processing system shown in  FIG. 1 ; 
         FIG. 13  is an illustration showing one example of a query command about stream data; 
         FIG. 14  is an illustration showing one example of an indexing method of input stream data; 
         FIG. 15  is an illustration showing index ID-applied stream data generated by an index ID-applied data generating module provided to the stream data processing system shown in  FIG. 1 ; 
         FIG. 16  is an illustration showing data stored in an index store table provided to the stream data processing system shown in  FIG. 1 ; 
         FIG. 17  is an illustration showing an example of index ID-applied data output from the processing data management module; 
         FIG. 18  is an illustration showing an example of index ID expression-applied processing result data output from the index ID-applied data processing module; 
         FIG. 19  is an illustration showing an example of data output from an indexed data output module provided to the stream data processing system shown in  FIG. 1  and an example of an index of the output data; 
         FIG. 20  is an illustration showing one example of processing by an application executed in a computer; 
         FIG. 21  is a block diagram showing an example of the configuration of an indexed stream data processing system equivalent to a third embodiment of the invention; 
         FIG. 22  is a block diagram showing an example of the configuration of an indexed stream data processing system equivalent to a fourth embodiment of the invention; 
         FIG. 23  is a block diagram showing an example of the configuration of an RFID reader equivalent to a fifth embodiment of the invention; 
         FIG. 24  is an illustration schematically showing an example of a suitable format of stream data input from a sensor node in the fifth embodiment of the invention; 
         FIG. 25  is an illustration showing an example of a query about the input stream data shown in  FIG. 24 ; 
         FIG. 26  is an illustration showing one example of an application that receives the result of the query shown in  FIG. 25  and its reliability and executes processing; and 
         FIG. 27  is a block diagram showing system configuration in which components configuring the stream data processing system equivalent to the first embodiment are arranged in CPU, a memory and an external storage. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings, embodiments of the invention will be described in detail below. In all the drawings for illustrating the embodiments, the same reference numeral is allocated to the same member in principle and its repetitive description is omitted. 
     First Embodiment 
       FIG. 1  is a block diagram showing an example of the configuration of a stream data processing system equivalent to a first embodiment of the invention,  FIG. 2  is a flowchart showing an example of the processing by an index ID applying module provided to the stream data processing system shown in  FIG. 1 ,  FIG. 3  is a flowchart showing an example of processing following the processing shown in  FIG. 2  by the index ID applying module,  FIG. 4  is a flowchart showing an example of processing following the processing shown in  FIG. 3  by the index ID applying module,  FIG. 5  is a flowchart showing an example of processing by a processing data management module provided to the stream data processing system,  FIG. 6  is a flowchart showing an example of processing by an index ID-applied data processing module provided to the stream data processing system,  FIG. 7  is a flowchart showing an example of processing by an indexed data generating module and an index ID evaluating module respectively provided to the stream data processing system,  FIG. 8  is a flowchart showing an example of processing following the processing shown in  FIG. 7  by the indexed data generating module and the index ID evaluating module,  FIG. 9  is a flowchart showing an example of processing by an index store module provided to the stream data processing system,  FIG. 10  is an illustration schematically showing one example of a data format of stream data used for the stream data processing system shown in  FIG. 1 ,  FIG. 11  is an illustration showing a product position measurement stream including continuously input stream data,  FIG. 12  is an illustration schematically showing an example of data stored in a reference data store management module provided to the stream data processing system shown in  FIG. 1 ,  FIG. 13  is an illustration showing one example of a query command about stream data,  FIG. 14  is an illustration showing one example of an indexing method of input stream data,  FIG. 15  is an illustration showing stream data with index ID generated by an index ID-applied data generating module provided to the stream data processing system shown in  FIG. 1 ,  FIG. 16  is an illustration showing data stored in an index store table provided to the stream data processing system shown in  FIG. 1 ,  FIG. 17  is an illustration showing an example of index ID-applied data output from the processing data management module,  FIG. 18  is an illustration showing an example of index ID expression-applied processing result data output from the index ID-applied data processing module,  FIG. 19  is an illustration showing an example of data output from an indexed data output module provided to the stream data processing system shown in  FIG. 1  and an example of an index of the output data, and  FIG. 20  is an illustration showing one example of application processing executed in a computer.  FIG. 27  showing one example in which components configuring the stream data processing system are arranged in CPU, a memory and an external storage and are executed. The arrangement of the components is not limited to that shown in  FIG. 27 , for example, the components configuring the memory  2702  are generated in the external storage  2714 , and their cache memory may be also realized in the memory  2702 . 
     In the first embodiment, the indexed stream data processing system  100  receives information transmitted at real time from an RFID reader  101 , a sensor node  102  or an application  104  executed in the computer  103  as stream data as shown in  FIG. 1 . 
     The indexed stream data processing system converts the stream data to significant information according to a command input by a user or by an application  110  executed in a computer  109 , generates output data and an index of the output data, and executes stream data processing provided to the user or an application  107  executed in a computer  106 . 
     The computer  109  is connected to the indexed stream data processing system  100  via a network  111 . The network  111  may be also Ethernet (a registered trademark), a fiber distributed data interface (FDDI), a local area network (LAN) connected via an optical fiber and others or a wide area network (WAN) including the lower-speed Internet than LAN. 
     The indexed stream data processing system  100 , the computer  103 , the computer  106  and the computer  109  are configured by an arbitrary computer system such as a personal computer and a workstation, and the arbitrary computer system may be also the same computer and a different computer. 
     The applications  104 ,  107 ,  110  may be also the same application and a different application. 
     Further, stream data in this embodiment is different from a stream used for the distribution of an image and voice and one stream data corresponds to significant information. 
     Stream data received by the indexed stream data processing system  100  from the RFID reader  101 , the sensor node  102  or the application  104  executed in the computer  103  is a series of continuous or intermittent data tuples. 
     A time stamp may be also applied by the RFID reader  101 , the sensor node  102  or the application  104  executed in the computer  103  or by a component except the RFID reader  101 , the sensor node  102  or the application  104  executed in the computer  103  before stream data is input to the indexed stream data processing system  100 . 
     The indexed stream data processing system  100  is operated in CPU  2701  of a computer  2700  in which the indexed stream data processing system  100  is executed and includes a command input module  119 , a query management module  118 , an indexing method management module  120 , the index ID applying module  130 , the processing data management module  140 , the index ID-applied data processing module  150 , the indexed data output module  160  and the index store module  170 . 
     The command input module  119  that functions as input means is similarly operated in the CPU  2701  of the computer  2700  in which the indexed stream data processing system  100  is executed and accepts a command and others input by a user or the application  104  executed in the computer. A command input method may be also a command line interface (CLI) format and a graphical user interface (GUI) format. 
     When the command is a command related to an indexing method, the command is output to the indexing method management module  120 . When the command is a command related to a query about stream data, the command is output to the query management module  118 . 
     The query management module  118  is similarly operated in the CPU  2701  and generates one or plural processing data management modules  140  and one or plural index ID-applied data processing modules  150  according to a query received from the command input module  119 . 
     The indexing method management module  120  is similarly operated in the CPU  2701 , selects a stored indexing method (stored index computation algorithm) according to a command received from the command input module  119 , and notifies the index ID applying module  130  of it. A new indexing method can be registered. 
     The index ID applying module  130  is similarly operated in the CPU  2701 , computes an index to be a first index of stream data, which is rating an incoming data tuple according to the indexing method notified from the indexing method management module  120 , generates an index ID, and outputs a set of the index, the index ID and time at which the index is computed to the index store module  170 . The index ID applying module outputs an index ID-applied stream data tuple which is a pair of the index ID and stream data tuple to the processing data management module  140 . 
     The processing data management module  140  is similarly operated in the CPU  2701 , receives the index ID-applied stream data from the index ID applying module  130 , and holds it. The processing data management module selects index ID-applied data which is a processing object out of held one or plural index ID-applied stream data according to a determining method specified when the processing data management module  140  is generated by the query management module  118  and outputs the index ID-applied data to the index ID-applied data processing module  150 . 
     When index ID-applied stream data eliminated from processing objects is included in the held index ID-applied stream data, the index ID-applied stream data is deleted and simultaneously, the index ID and time at which the index ID-applied stream data is judged eliminated from the processing objects are notified the index store module  170 . 
     The index ID-applied data processing module  150  is similarly operated in the CPU  2701 , receives the index ID-applied data from the processing data management module  140 , generates index ID expression-applied processing result data which is a set of one or more index IDs, an index ID expression described by zero or more operators and processing result data based upon the index ID-applied data according to a method specified when the index ID-applied data processing module  150  is generated by the query management module  118 , and outputs it to the indexed data output module  160 . 
     The indexed data output module  160  is similarly operated in the CPU  2701 , receives the index ID expression-applied processing result data from the index ID-applied data processing module  150 , receives an index corresponding to index ID included in the index ID expression-applied processing result data from the index store module  170 , computes an index corresponding to an index ID expression of the index ID expression-applied processing result data using the index, and outputs output data which is a data division of the index ID expression-applied processing result data and an index which is a second index of the output data to the user or the application  107  executed in the computer  106 . 
     The index store module  170  receives a set of the index, the index ID and time at which the index is computed from the index ID applying module  130  and stores the set. Besides, the index store module receives the index ID and time at which index ID-applied stream data including the index ID is eliminated from the processing objects from the processing data management module  140  and records them. 
     Besides, the index store module receives the index ID and the time from the indexed data output module  160 , returns an index at the time of the index ID, determines index ID not required to be held, and deletes data related to the index ID. 
     The configuration of the indexed stream data processing system  100  will be described in detail below. 
     The indexing method management module  120  includes an indexing method selecting module  121 , an indexing method input module  122  and an indexing method store module  123  and receives a command input from a user or the application  110  executed in the computer  109  via the command input module  119 . 
     When the command input from the command input module  119  is a command related to the registration of a user defined indexing method which is an indexing method uniquely defined by the user, the indexing method input module  122  outputs the user defined indexing method to the indexing method store module  123  and the indexing method store module  123  stores the user defined indexing method. 
     When the command input from the command input module  119  is a command related to the selection of an indexing method, one is selected out of zero or more indexing methods registered in the indexing method store module  123  beforehand or one or plural indexing methods uniquely defined by the user and is notified an index computing module  132  and a reference data store management module  133 . 
     The index ID applying module  130  includes an index ID-applied data generating module  131 , the index computing module  132 , the reference data store management module  133  and a reference data store table  134 . 
     It is desirable that the reference data store table  134  is generated in a high-speed random access storage such as a memory; however, it may be also generated in another storage such as a disk. In that case, access may be also sped up using a cache memory and others. 
     Referring to  FIGS. 2 ,  3  and  4 , processing by the index ID applying module  130  will be described below. 
     First, the index ID applying module  130  receives stream data, generates index ID in the index ID-applied data generating module  131  (a step S 1302 ), and passes the stream data to the reference data store management module  133  together with the generated index ID (a step S 1303 ). 
     The reference data store management module  133  stores the stream data in the reference data store table  134  together with the index ID (a step S 1503 ). The index ID-applied data generating module  131  passes the index ID to the index computing module  132  (a step S 1304 ). 
     Next, the index computing module  132  inquires the reference data store management module  133  of a data set required for index computing according to an indexing method specified by the indexing method management module  120  (a step S 1402 ) and the reference data store management module  133  returns the required data set. 
     The reference data store management module  133  reads data by one row from the reference data store table  134  (a step S 1505 ) and determines whether the read row is required for index computing or not (a step S 1506 ). 
     When the read row is required in the processing in the step S 1506 , the data on the read row is added to the data set (a step S 1508 ) and when the read row is not required, the row is deleted from the reference data store table  134  (a step S 1507 ). 
     The reference data store management module  133  executes the processing in the steps S 1505  to S 1508  by all rows of the reference data store table  134  (a step S 1509 ). 
     The index computing module  132  computes an index of each element of the acquired data set according to the indexing method (a step S 1403 ) and stores the indexes in the index store module  170  (a step S 1404 ). 
     The index computing module  132  executes the processing in the steps S 1403  and S 1404  for all elements of the data set (a step S 1405 ). The index computing module  132  outputs the computed indexes of data and the number of the processing data management modules  140  which are destinations of output to an index store management module  171  (a step S 1305 ). 
     An index may be computed every time a data tuple of the stream is input and also at time except it. The index ID-applied data generating module  131  outputs index ID-applied stream data which is a pair of stream data and index ID to one or plural processing data management modules  140  as shown in  FIG. 2  (a step S 1306 ). 
     The processing data management module  140  includes a processing data store management module  141  and a processing data store table  142 . 
     Referring to  FIG. 5 , processing by the processing data management module  140  will be described below. 
     The processing data store management module  141  receives the index ID-applied stream data from the index ID applying module  130  and stores it in the processing data store table  142  (a step S 1602 ). 
     The processing data store management module selects index ID-applied data which is a processing object from the processing data store table  142  according to a determining method specified when the processing data management module  140  is generated by the query management module  118  and outputs the selected index ID-applied data to the index ID-applied data processing module  150  (a step S 1603 ). 
     The processing data store management module  141  deletes the corresponding index ID-applied stream data from the processing data store table  142  when the index ID-applied stream data eliminated from a processing object is judged existing in the processing data store table  142  by the determining method (a step S 1604 ) and simultaneously, notifies the index store module  170  of index ID of the index ID-applied stream data and time at which the index ID-applied stream data is judged eliminated from a processing object (a step S 1605 ). 
     The index ID-applied data processing module  150  includes a data processing module  151  and an index ID processing module  152 . 
     Referring to  FIG. 6 , processing by the index ID-applied data processing module  150  will be described below. 
     The index ID-applied data processing module  150  receives the index ID-applied data from the processing data management module  140 , generates output data based upon a data division of the index ID-applied data in the data processing module  151  according to a method specified when the index ID-applied data processing module  150  is generated by the query management module  118  (a step S 1702 ), generates an index ID expression described with one or more index IDs and zero or more operators based upon index ID of the index ID-applied data in the index ID processing module  152  (a step S 1703 ), generates index ID expression-applied processing result data which is a pair of the output data and the index ID expression, and outputs the data to the indexed data output module  160  (a step S 1704 ). 
     The indexed data output module  160  includes an indexed data generating module  161  and an index ID evaluating module  162 . 
     Referring to  FIGS. 7 and 8 , processing by the indexed data generating module  161  and the index ID evaluating module  162  will be described below. 
     The indexed data generating module  161  receives the index ID expression-applied processing result data from the index ID-applied data processing module  150  and passes received time of the index ID expression-applied processing result data and the index ID expression included in the index ID expression-applied processing result data to the index ID evaluating module  162  (a step S 1802 ). 
     The index ID evaluating module  162  generates a set of index IDs included in the index ID expression (a step S 1902 ) and inquires the index store module  170  of the corresponding indexes for each element of the set of index IDs (a step S 1903 ). 
     The index ID evaluating module  162  executes the processing in the step S 1903  for all elements of the set of index IDs (a step S 1904 ). The index ID evaluating module computes an index corresponding to the index ID expression in the index ID expression-applied processing result data using the acquired indexes and outputs it to the indexed data generating module  161  (a step S 1905 ). 
     The indexed data generating module  161  outputs data equivalent to the data division of the index ID expression-applied processing result data and the index of the output data which is the index received from the index ID evaluating module  162  to a user or the application  107  executed in the computer  106  (a step S 1803 ). 
     The index store module  170  includes the index store management module  171  and an index store table  172 . It is desirable that the index store table  172  is generated in a high-speed random access storage such as a memory; however, it may be also generated in another storage such as a disk. In that case, access may be also sped up using a cache memory and others. 
     Referring to  FIG. 9 , processing by the index store module  170  will be described below. 
     The index store management module  171  receives the index ID, the index, the index computed time and the number of processing data instances which is the number of the processing data management modules  140  to which the index ID-applied stream data is to be output from the index ID-applied data generating module  131  and stores them in the index store table  172  (a step S 2003 ). 
     The index store management module also receives the index ID and time at which the index ID-applied stream data having the index ID is eliminated from a processing object from the processing data store table  142 , retrieves a row of index IDs in the index store table  172  (a step S 2005 ), and holds the time in the index store table  172  as time at which the processing data instance becomes void (a step S 2007 ) when the number of the processing data instances is 1 (a step S 2006 ). 
     When the number of processing data instances is not 1 (a step S 2006 ), the number of processing data instances is decremented by 1 (a step S 2008 ). The index store management module retrieves an index at the time of the index ID based upon the index ID and the time respectively received from the index ID evaluating module  162  and returns the index (a step S 2010 ). 
     The index store management module deletes the corresponding index ID from the index store table  172  because the corresponding index ID is not referred subsequently when the index store table  172  includes the index ID the processing data instance voidance time of which precedes the time received from the index ID evaluating module  162  (a step S 2011 ). The processing in the step S 2011  may be also executed every time time is received from the index ID evaluating module  162  and at the other time. 
       FIG. 10  schematically shows an example of a suitable data format of input stream data shown in  FIG. 1 . 
     Stream data complies with a record format, a time stamp  201 , product ID  202  and a product position  203  respectively configuring a record are equivalent to a segment, and a combination of the time stamp  201 , the product ID  202  and the product position  203  is equivalent to a tuple. 
       FIG. 10  shows an example of position measurement data of a product in a smart shelf system, the product to which an RFID tag is added is exhibited on a smart shelf on which an RFID reader is installed, the RFID tag is read at an interval of one second using the RFID reader, and as a result, when the RFID reader reads the RFID tag, the product having the RFID tag is judged existing on the shelf. 
     When the RFID reader does not read the RFID tag, the RFID tag is judged existing out of the shelf, and time  201  at which the RFID reader reads the RFID tag, product ID  202  of the product to which the RFID tag is added and the determined product position  203  are output. 
       FIG. 11  shows a product position measurement stream  310  including continuously input stream data. 
       FIG. 11  shows that on a row  301  for example, a value of a time stamp is “10: 00′ 02”, product ID is “product 1” and a product position is “inside shelf”. 
     In this embodiment, the time stamp is represented in the order of an hour, a minute and a second like “10: 00′ 02”, however, the time stamp may be also represented in another format represented by a format including a date like “2007/3/3 10: 00′ 02 JST”. It is similar in the following drawings. 
       FIG. 12  schematically shows an example of data stored in the reference data store management module  133 . 
     In this case, the time at which the RFID reader reads the RFID tag  201 , the product ID  202  of a product to which the RFID tag is added and the product position  203  determined according to the above-mentioned method respectively included in stream data are stored in columns  1001 ,  1002  and  1003  and the index IDs generated in the index ID-applied data generating module  131  are stored in a column  1004 . 
       FIG. 13  shows one example of a query command about stream data. A format of the query command may be also the format shown in  FIG. 13  and the other format. 
     The query command  1101  is transmitted from a user or the application  110  executed in the computer  109  to the query management module  118  via the command input module  119 . The query management module  118  generates the processing data management module  140  that realizes the query command  1101  and the index ID-applied data processing module  150 . 
     The query command  1101  means a query that demands product ID of a taken product from the product position measurement stream  310  ( FIG. 11 ). That is, the query command means a query that demands the output (SELECT S. product) of product ID which has the same product ID (S 1 . product=S 2 . product) as the product position measurement stream  310 , the current (S[now] as S 1 ) position of which is outside the shelf (S 1 . position=outside shelf) and the position at the preceding time of which is inside the shelf (S[rows  2 ] as S 2 , S 2 . position=inside shelf). 
     Next, processing for executing the query will be described. 
       FIG. 14  shows one example of an indexing method of input stream data to be the algorithm of an index function. 
     In the indexing method in this embodiment, when the same time series data continues, the reliability of the data is set to be high and when different data continues, the reliability of the data is set to be low. 
     In  FIG. 14 , d i−1 , d i , and d i+1  are data stored in the reference data store table  134 . “d i ” is data of an object the index of which is computed, and d i−1  and d i+1  are data before and after d i . 
     When data before or after d i  is not an object the index of which is computed, d i−1  is null or d i+1  is null. As d i  is data of an object of the indexing method, d i  is not null. 
     According to the indexing method shown in  FIG. 14 , when the data before and after d i  are both objects of the indexing method, the reliability of d i  is 1.0 if d i  is the same as the data before and after d i , if d i  is the same as either of the data before and after d i , the reliability of d i  is 0.7, and if d i  is different from the data before and after d i , the reliability of d i  is 0.3. 
     When the data after d i  is not the object of the indexing method though the data before d i  is the object of the indexing method, the reliability of d i  is 1.0 if d i  is the same as the data before d i  and if d i  is different from the data before d i , the reliability of d i  is 0.5. 
     When the data before d i  is not the object of the indexing method and the data after d i  is the object of the indexing method, the reliability of d i  is the same as the reliability of d i  computed at the preceding time. When the data before and after d i  are both not the object of the indexing method (d i−1 =null and d i+1 =null), the reliability of d i  is 0.5. 
       FIG. 15  shows an index ID-applied stream data generated in the index ID-applied data generating module  131 . 
     The time stamp  201 , the product ID  202  and the product position  203  respectively shown in  FIG. 10  correspond to a time stamp  501 , product ID  502  and a product position  503  and in addition, index ID  504  is applied. 
       FIG. 16  shows data stored in the index store table  172 . Data  610  which is a pair of time at which an index is computed  602  and an index  603  is stored every index ID  601 . 
     For example, in a field of index ID “p1”, it is stored that an index at the time of “10: 00′ 02” is 1.0. At the time shown in  FIG. 16 , index ID “p2” is left in one processing data management module  140 , index ID “p3” is left in the other two processing data management modules  140 , and the index ID “p1” is eliminated from all processing data management modules  140  at the time of “10: 00′ 04”. 
       FIG. 17  shows an example of index ID-applied data output from the processing data management module  140 . 
     A table  701  shows an example of index ID-applied data output from one processing data management module  140  and a table  710  shows an example of index ID-applied data output from the other one processing data management module  140 . 
       FIG. 18  shows an example of index ID expression-applied processing result data output from the index ID-applied data processing module  150 . 
     The index ID expression-applied processing result data is configured by a time stamp  801  which is a data division, product ID  802  and an index ID part  803 . As for the index ID part  803 , index ID-applied data  702 ,  703  out of index ID-applied data  701 ,  702 ,  703  input to the index ID-applied data processing module are generated based upon the index ID part  803 . 
     In this embodiment, the index ID part  803  includes minimum values of the index ID-applied data  702 ,  703 ; however, they may be also determined by another method. 
       FIG. 19  shows an example  810  of data output from the indexed data output module  160  and an example  803  of an index of the output data. 
     A value of the index ID part  803  in the example of the index ID expression-applied processing result data shown in  FIG. 18  is computed using the index stored in the index store module  170 , 0.5 is acquired, and it is output as the index of the output data. 
       FIG. 20  shows one example of processing by the application  107  executed in the computer  106 . 
     When the output data shown in  FIG. 19  and the index of the output data are received, the retrieval of product information is executed because reliability that a product is taken out of the shelf is 0.5. When reliability that the product is taken out of the shelf is 0.6, product information is displayed. 
     The takeout information of a product and its final reliability are stored and afterward, analysis is made using stored takeout information and their reliability. For example, a takeout frequency of a product is totalized, when a popular product frequently taken out of the shelf is extracted, only data having high reliability such as 0.8 or higher is analyzed as a takeout event and a product frequently taken out of the shelf is extracted. When an unpopular product hardly taken out of the shelf is extracted, data the reliability of which is 0.1 or lower for example is regarded as not a takeout event and is analyzed. 
     As described above, the reliability of an input stream is computed and the input stream can be processing according to a query registered by a user beforehand. 
     Thereby, according to this embodiment, as the reliability of an input stream is evaluated again based upon input stream data that varies every moment and can be utilized for the reliability of a result of output, data processing in which real time and reliability are compatible is enabled. 
     Second Embodiment 
     In the first embodiment, as shown in  FIG. 1 , one index ID-applied stream data is output to one or plural processing data management modules  140 , however, in a second embodiment, one index ID-applied stream data is output to only one processing data management module  140 . 
     In the second embodiment, the configuration except the respective configuration of an index ID-applied data generating module  131 , an index store management module  171  and an index store table  172  is similar to the configuration shown in  FIG. 1  in the first embodiment. 
     In the first embodiment, in the index store module  170 , to determine whether each index ID is required to be held in the index store table  172  or not, the number of index ID-applied stream data instances is stored in the index store table  172 , however, in the second embodiment, the number of index ID-applied stream data instances is not stored. 
     An index ID applying module  130  receives stream data, generates index ID in an index ID-applied data generating module  131 , and passes the stream data to a reference data store management module  133  together with the generated index ID. 
     The reference data store management module  133  stores the stream data together with the index ID in a reference data store table  134 . The index ID-applied data generating module  131  passes the index ID to an index computing module  132 . 
     The index computing module  132  extracts a data set required for computing an index from the reference data store management module  133  according to an indexing method specified by an indexing method management module  120 , computes indexes of respective data included in the data set according to the indexing method, and outputs them to an index store module  170 . 
     Data not required for computing an index according to the indexing method in the reference data store table  134  is deleted by the reference data store management module  133 . An index may be also computed every time stream data is input and at the other time. 
     The index ID-applied data generating module  131  outputs index ID-applied stream data which is a pair of stream data and index ID to one processing data management module  140 . 
     The index store management module  171  receives the index ID, the index and time at which the index is computed from the index ID-applied data generating module  131  and stores them in the index store table  172 . The index store management module also receives index ID and time at which index ID-applied stream data having the index ID is eliminated from an processing object from a processing data store table  142  and holds the time as processing data instance voidance time in the index store table  172 . The index store management module also retrieves an index at the time of the index ID based upon index ID and time respectively received from an index ID evaluating module  162  and returns the index. 
     As the corresponding index ID is not referred subsequently when the index store table  172  includes the index ID the processing data instance voidance time of which precedes time received from the index ID evaluating module  162 , the index ID is deleted from the index store table  172 . This processing may be also executed every time the time is received from the index ID evaluating module  162  and at the other time. 
     Thereby, according to the second embodiment, in such a query that one stream is input to only one processing data management module, the quantity of processing required for data management in the index store module  170  can be reduced. 
     Third Embodiment 
       FIG. 21  is a block diagram showing an example of the configuration of an indexed stream data processing system equivalent to a third embodiment of the invention. 
     In the third embodiment, an index ID expression is output in place of an index of the result of processing. A component that accepts a command for acquiring an index based upon the output index ID expression is included and when the command for acquiring the index is input, an index of the index ID expression is computed. 
       FIG. 21  is the block diagram showing the configuration of the indexed stream data processing system equivalent to the third embodiment and its related system. 
     As shown in  FIG. 21 , the indexed stream data processing system  2100  includes a computer or a server for example. The indexed stream data processing system  2100  receives information transmitted at real time from an RFID reader  2101 , a sensor node  2102  or an application  2104  executed in a computer  2103  as stream data, converts the stream data to significant information according to a command input from an application  2110 , and generates index ID-applied processing result data which is the result of processing. 
     The indexed stream data processing system provides the index ID-applied processing result data to an application  2107  and executes stream data processing for outputting an index according to a command input from an application  2114 . 
     The application  2110  is executed by a user or a computer  2109 , the application  2107  is executed by a user or a computer  2106 , and the application  2114  is executed by a user or a computer  2113 . 
     In  FIG. 21 , components except the indexed stream data processing system  2100 , the computer  2113  and the application  2114  are similar to those in the first and second embodiments. The computer  2113  and the application  2114  may be also the same as the computer  2106 , the computer  2109 , the application  2107  or the application  2110  and may be also different from them. 
     In the indexed stream data processing system  2100  shown in  FIG. 21 , components except an index ID evaluating module  2160  and a command input module  2117  are the same as those in the first and second embodiments. 
     The command input module  2117  accepts a command from the application  2114  executed in the computer  2113 , outputs an instruction for evaluating an index ID expression specified in the command to the index ID evaluating module  2160  when the command is a command related to the evaluation of the index ID expression, receives an index of the result of evaluation from the index ID evaluating module  2160 , and outputs it to the user or the application  2114  executed in the computer  2113 . When the command is a command related to the deletion of index ID, the command input module outputs an instruction for deleting index ID specified in the command to an index store management module  2171 . 
     The index ID evaluating module  2160  receives the instruction for evaluating the index ID expression from the command input module  2117 , acquires an index corresponding to index ID included in the index ID expression from the index store management module  2171 , computes an index corresponding to the index ID expression based upon the index, and outputs the computed index to the command input module  2117 . 
     Thereby, in the third embodiment, the quantity of processing required for unnecessary conversion can be reduced by executing conversion from the index ID to the index at arbitrary time that requires conversion. 
     Fourth Embodiment 
       FIG. 22  is a block diagram showing an example of the configuration of an indexed stream data processing system equivalent to a fourth embodiment of the invention. 
     In the fourth embodiment, technique that handles a pair of stream data and an index without generating index ID will be described. 
       FIG. 22  is the block diagram showing the configuration of the indexed stream data processing system to which one embodiment of the invention is applied and a system related to it. 
     In  FIG. 22 , components except the indexed stream data processing system  2200  are similar to those in the first embodiment shown in  FIG. 1 . 
     The indexed stream data processing system  2200  includes a command input module  2219 , a query management module  2218 , an indexing method management module  2220 , an index applying module  2230 , a processing data management module  2240  and an indexed data processing module  2250 . 
     The command input module  2219 , the query management module  2218  and the indexing method management module  2220  are similar to the command input module  119 , the query management module  118  and the indexing method management module  120  which are respectively the components in the first embodiment. 
     The index applying module  2230  includes an indexed data generating module  2231 , an index computing module  2232 , a reference data store management module  2230  and a reference data store table  2234 . 
     The indexed data generating module  2231  receives stream data from an RFID reader  2201 , a sensor node  2202  or an application  2204  executed in a computer  2203  and outputs the received stream data to the reference data store management module  2233 . 
     The indexed data generating module also issues an instruction for computing an index to the index computing module  2232 , receives the computed index and the stream data from the index computing module  2232 , and outputs indexed stream data which is a pair of the index and the stream data to the processing data management module  2240 . 
     The index computing module  2232  receives the instruction for computing the index from the indexed data generating module  2231 , extracts data for computing an index from the reference data store management module  2233 , computes an index of the data according to an indexing method specified by the indexing method management module  2220 , and outputs the data and the index to the indexed data generating module. 
     The reference data store management module  2233  stores the stream data received from the indexed data generating module  2231  in the reference data store table  2234 . 
     The processing data management module  2240  includes a processing data store management module  2241  and a processing data store table  2242 . The processing data store management module  2241  receives the indexed stream data from the index applying module  2230 , stores it in the processing data store table  2242 , and outputs it to the indexed data processing module  2250  as indexed data. 
     When indexed stream data the stream data division of which is the same as that of the indexed stream data and the index of which is different is already stored in the processing data store table  2242 , the processing data management module changes the index of the indexed stream data in the processing data store table  2242  to the index of the received indexed stream data. 
     Simultaneously, the processing data management module notifies the indexed data processing module  2250  that the index is changed. The processing data store management module  2241  deletes the indexed stream data eliminated from processing data from the processing data store table  2242  according to a method specified when the processing data management module  2240  is generated by the query management module  2218 . 
     The indexed data processing module  2250  includes a data processing module  2251  and an index processing module  2252 . 
     The indexed data processing module  2250  receives the indexed data from the processing data management module  2240 , generates output data based upon a data division of the indexed data in the data processing module  2251  according to a method specified when the indexed data processing module  2250  is generated by the query management module  2218 , generates an index of the output data based upon an index of the indexed data, and outputs the output data and the index of the output data to a user or an application  2207  executed in a computer  2206 . 
     The indexed data processing module  2250  receives notice that the index is changed from the processing data management module  2240  and computes an index of the output data in consideration of the notice that the index is changed in the index processing module  2252 . 
     Thereby, in the fourth embodiment, the configuration of the indexed stream data processing system  2200  can be simplified and the cost can be reduced. 
     Fifth Embodiment 
       FIG. 23  is a block diagram showing an example of the configuration of an RFID reader equivalent to a fifth embodiment of the invention. 
     In the fifth embodiment, an example that the reliability of input stream data is acquired based upon plural measurement data is shown. In this embodiment, components of the system are similar to those in the first embodiment: however, the components may be also similar to those of any of the first to fourth embodiments. 
       FIG. 23  shows an example of the configuration of the RFID reader  2300 . 
     For example, ten antennas  2301  to  2310  are connected to the RFID reader  2300 . The antennas  2301  to  2310  are arranged so that each RFID from each RFID reader provided on a shelf for example is read by at least one antenna. 
     An RFID tag can be prevented from being unread by the antennas  2301  to  2310  arranged as described above. The RFID tag can be prevented from being unread at a lower price than a price when the number of the RFID readers is increased by increasing the number of the lower-priced antennas than the RFID reader like the configuration shown in  FIG. 23 . In this embodiment, ten antennas are provided, however, an antenna or antennas of an arbitrary number equal to or exceeding one may be provided. 
     The RFID reader  2300  switches the antennas  2301  to  2310  at an interval of 0.1 second in the order, reads the RFID tag, and transmits the read information of the RFID tag to the indexed stream data processing system  100  shown in  FIG. 1  in the read order as stream data. 
     For example, the information of the RFID tag read by the antennas  2301 ,  2302 ,  2303  appear three times in the stream data. The index computing module  132  computes the reliability of read data of the RFID tag read by at least one antenna out of the antennas  2301  to  2310  according to a method described later. 
     When the more antennas read the RFID tag, the reliability of the read data increases and when the fewer antennas read the RFID tag, the reliability decreases. For example, as fluctuation may occur when the RFID tag is read by only the antenna  2301 , the reliability is judged as 0.5 and when the RFID tag is read by the two antennas  2301  and  2310 , the reliability is judged as 1.0. 
     As the RFID reader  2300  switches the antennas  2301  to  2310  at an interval of 0.1 second for example and performs reading, time at which the RFID tag is read by the antenna  2310  is delayed by approximately 1.0 second from time at which the RFID tag is read by the antenna  2301 . 
     Therefore, when the read reliability of the RFID tag is computed according to the method of computing reliability, the reliability is first 0.5 when the RFID tag is read by the antenna  2301  and the reliability is 1.0 when the RFID tag is read by the antenna  2310  after approximately 1.0 second. 
     When it is supposed that approximately one second is required for retrieving product information in the application shown in  FIG. 20 , the product information is displayed in approximately one second since the time at which the RFID tag is read by the antenna  2301 . 
     In the case of a system that product information is retrieved and displayed since it is clarified that the RFID tag is read by two or more antennas out of the antennas  2301  to  2310  for example without utilizing the invention, approximately 2.0 second is required since time at which the RFID tag is read by the antenna  2301  to display product information. 
     Thereby, in the fifth embodiment, the reliability of data can be acquired based upon plural measurement data. 
     Sixth Embodiment 
       FIG. 24  is an illustration schematically showing an example of a suitable format of stream data input from the sensor node in the fifth embodiment of the invention,  FIG. 25  is an illustration showing an example of a query about the input stream data shown in  FIG. 24 , and  FIG. 26  is an illustration showing one example of an application that receives the result of the query shown in  FIG. 25  and its reliability and executes processing. 
     In a sixth embodiment, an example of a method of computing the reliability of data input from the sensor node will be described. In the sixth embodiment, components of a system are similar to those in the first embodiment; however, the components may be also similar to those in any of the first to fourth embodiments. For the configuration of a related system, data shall be input from the sensor node  102  shown in  FIG. 1 . 
     The sensor node  102  continuously measures the temperature of a room for example every 10 seconds and transmits a pair of ID of the room and measured temperature to an indexed stream data processing system  100  as stream data. An interval of measurement may be also 10 seconds and the other. 
       FIG. 24  schematically shows the example of the suitable format of stream data input from the sensor node  102  and the format is configured by temperature measurement time  2401 , room ID  2402  and the measured temperature of the room  2403 . 
     An index computing module  132  computes the reliability of input stream according to a method described later. It is normally inconceivable that the temperature of the room rises by ten degrees for ten seconds, however, it may occur in the case of emergency such as the occurrence of fire. 
     In the meantime, it is inconceivable that the temperature of the room falls by ten degrees for ten seconds. Then, when the temperature rises by ten or more degrees for ten seconds, reliability is judged as 0.5 and when high temperature also continues afterward, reliability is judged as 0.9. 
     In the meantime, when the temperature of the room falls by ten or more degrees for ten seconds after it rises by ten or more degrees, reliability is lowered up to 0.1. In the sixth embodiment, the rise of temperature is set to ten degrees; however, the rise may be also a value except it. 
       FIG. 25  shows the example of a query about input stream data. 
     With the newest measured temperature every room (GROUP BY roomID) as an object (FROM S[now]), ID of a room the temperature of which is 40 or more degrees (WHERE S. temperature&gt;40) is output (SELECT S. roomID). 
       FIG. 26  shows the example of the application that receives the result of the query shown in  FIG. 25  and its reliability and executes processing. 
     When the temperature of the room exceeds 40 degrees and its reliability is 0.5, the situation is notified a guard to be an alert. When the temperature of the room exceeds forty degrees and its reliability is 0.9, a sprinkler is activated. 
     When fire occurs in the room, the sprinkler is activated and work for fighting fire is required, however, when a temperature sensor fails and no fire occurs, large loss is caused if the sprinkler is activated. 
     As described above, when it is possible that the temperature sensor fails, processing having smaller risk than the activation of the sprinkler such as notice to the guard can be selected. 
     Thereby, in the sixth embodiment, the reliability of multivalued measurement data input from the sensor can be enhanced. 
     The invention made by these inventors has been concretely described based upon the embodiments, however, the invention is not limited to the embodiments and it need scarcely be said that the invention can be variously modified in a range which does not deviate from the object. 
     The invention is suitable for stream processing technique for receiving stream data from the RFID reader and the sensor, applying reliability to the result of the processing of the input data and outputting the stream data.