JP4498262B2 - Information sharing method in distributed system - Google Patents

Description

  The present invention is a distributed system in which one or more networks are included and connected to each other, and the components of the system are not always connected to a constant network such as a mobile unit, a mobile terminal, or a sensor. The present invention relates to a system that may include elements, and particularly relates to information sharing / distribution that guarantees responsiveness between necessary parties in the system according to business contents and the like.

  There has been proposed a method for realizing information sharing even when a system configuration change occurs, by multicast transmission of data from a data source into the network of the system and selective reception on the data request side.

For example, a large number of programmable logic controllers (PLCs) for monitoring and controlling process-side equipment and facilities, multiple MMIs (man machine interfaces) installed at multiple monitoring bases, and optional connection between these PLCs and MMIs In a distributed control system that connects to a network to transmit control commands and process information, a location number is assigned to each monitoring base, and the monitoring base of the control command and process information between the MMI and PLC is set by this location number setting. A distributed control system comprising a control LAN (local area network) protocol that specifies one or a plurality of communication destinations, and specifies a destination by multicast by omitting a location number, MMI number, or PLC number ( Patent Document 1) has been proposed.
JP 2003-18215 A

  In the above prior art, when multicast communication is performed, a message reaches a node that does not request data, and it is necessary to determine whether or not received data is necessary for the own node in all received nodes. . For this reason, when the number of nodes increases, the network load and the load of received data determination processing at each node increase, which may interfere with real-time communication and processing in the system.

  In addition, the data requesting side such as the user's mobile terminal or the data source such as the moving body or the sensor is not always connected to the network for movement, network conditions, short-range wireless use, etc. When communication and information sharing are performed, a response to a data request cannot be guaranteed within the limited connection time of these components. For example, in multicast communication, there is a possibility that data cannot be received within a limited connection time because of message transmission delay or failure due to network conditions.

  Accordingly, the present invention has been made in view of the above problems, and is a distributed system in which one or more networks are connected to each other. The system components include emergency connection elements such as mobile objects, mobile terminals, or sensors. Including any case where the data source or data requester in the system is not always connected to the network without interfering with the communication and processing in the system in real time, including the case where replacement etc. may occur The main purpose is to provide an information sharing method that guarantees responsiveness to data requests from any other communication path.

In order to solve the above problems and achieve the object of the present invention, the information sharing method in the distributed system of the present invention searches for information related to the identification information of the data requester from the data storage areas distributed in the system. A step of creating replica creation information for creating a replica including a data type and an arrangement location based on the related information, and the replica creation information is within a range designated as a replica arrangement location. Select a replica that is suitable for the data request from among the replica creation information that is shared among two or more data storage areas and that includes the replica creation information created for the data requester. Based on the information, a step of creating a replica of the data in the data storage area in advance, and an application from the data requesting side corresponding to the identification information. If there is an access, the step of returning a response from the data storage area using the replica of the data, and the source of the data to generate the replica or the location of the replica are changed according to the state of the replica on the data source side A step of deleting a replica of data that has not been referred to or has a low reference frequency after a certain period of time from the data storage area, and a replica of data that the data requester may request Determining the type of data for creating the replica by referring to the access history of the data requesting side and extracting the data with a track record referred to in the past when creating the replica creation information of Is included.

  Further, in the above, the present invention refers to the schedule information related to the data requesting side when creating the replica creation information for generating a replica of the data that the data requesting side may request, and the data requesting side And determining the location of the replica based on the scheduled action range on the side.

  Further, in the above, the present invention refers to the location information of the data requester when creating replica creation information for creating a replica of data that the data requester may request, and A location of the replica is determined from a range around the current position on the side.

  Further, in the above, the present invention refers to the access history of the data requesting side and refers to the past when creating replica creation information for generating a replica of data that the data requesting side may request. The step of determining the placement location of the replica based on a proven location is included.

  Further, in the above, when the data requesting side to which the identification information is distributed requests data, the present invention accesses the nearest data storage area from a node on which the data requesting side operates and acquires data. Includes steps.

  Further, the present invention provides a data source that is accessible from the data storage area by referring to schedule information and route information related to the data source when changing the data source for generating the replica. Selection, the access time to the data source, the frequency, etc. are included.

  Further, in the above, the present invention refers to data accessible from the periphery of the data storage area by referring to the location information or the survival signal of the data source when changing the data source for generating the replica. The method includes a step of selecting a source and determining an access time and frequency to the data source.

  Further, in the above, the present invention includes a step of deleting information related to the data requesting side from the reservation list in the data storage area when there is no access from the data requesting side corresponding to the identification information even after a certain period of time. Is included.

  According to the present invention, in a distributed system in which one or more networks are connected to each other, a system component that is not always connected to the network, or a system component that can also be replaced, By sharing information without being aware of differences in networks, it is possible to guarantee responsiveness even for data requests from any communication path without interfering with communication and processing in the real-time system.

Embodiments of the present invention will be described below with reference to the drawings as appropriate.
FIG. 1 is a configuration diagram of an information sharing system.
FIG. 1 shows a distributed system in which one or more networks according to the present embodiment are included and connected to each other, and mobile terminals and sensors equipped with short-range radio, a moving mobile body, etc. It is a figure which shows the outline | summary of the system also including the component which is not necessarily connected to the network.

  This system is connected via a communication network 0105 via a first base 0102 and a second base 0103 mainly constructed by an information network, a factory 0104 mainly constructed by a control network, and a radio base station 0131. This is a wide area information control system in which multiple bases dispersed in a wide area such as a mobile body 0106 connected by wireless communication are interconnected.

  The main components of this system are the information system and the control system, which are installed at the first base 0102, the second base 0103, and the factory 0104, respectively. There is a gateway server 0107 that performs relaying and the like, and a gateway server 0107 that is also connected to a radio base station 0131 that communicates with the mobile unit 0106.

  In addition, as another constituent element, in this system, a user 0101 that performs data access from a mobile terminal or the like via short-distance wireless communication via an access point or the like or a node in which a user program used for business use is installed The authentication server 0110 installed in the system for authenticating the fixed terminal 0111 or the like, operates in the factory 0104, and is the data / source equipment / device 0108 or the data via the nearest access point by short-range wireless communication. There is a sensor tag 0109 or the like that is not always connected to the network that always transmits.

  The main hardware configuration of the gateway server 0107 includes a processing device 0121, a communication device 0122, and a storage device 0123. The storage device 0123 collects data from data sources such as equipment / devices 0108 and sensors / tags 0109 and stores the data for provision to data request sources such as users 0101 and fixed terminals 0111. In addition to the data storage area 0124, communication is performed with software for managing the data storage area 0124, data sources such as equipment / device 0108 and sensor / tag 0109, and data request sources such as the user 0101 and the fixed terminal 0111. Software and the like are stored and processed by the processing device 0122.

  The communication device 0122 is a communication for performing data collection from data sources such as equipment / devices 0108 and sensors / tags 0109 and receiving requests and providing data from data request sources such as users 0101 and fixed terminals 0111. Process.

  As described above, the system according to the present embodiment is a distributed system in which one or more networks are included and connected to each other, and not only a fixed node but also a mobile terminal, a mobile unit, a sensor tag, etc. Thus, system components that are not always connected to the network are also included.

FIG. 2 is a configuration diagram of the gateway server.
FIG. 2 is a diagram showing an embodiment of the present invention. FIG. 2 is an example of a system in a distributed system that accepts access from an access point from a mobile terminal of a user who is not always connected or a user's mobile terminal, a mobile unit, etc. It is a figure which shows the module structure of the gateway server which arrange | positions a replica.

  The gateway server 0107 communicates with a node on which a user program operates or a user 0101 mobile terminal that is not always connected via the communication medium 0202, accepts a data request, generates a data replica, etc. In addition, middleware 0201 that performs processing such as storage and management of stored data is introduced.

  The main components of the middleware 0201 are a data storage area 0211 for storing data replicas, a history storage area 0212 for storing history of access and data reference from users, and identification of users from an authentication server or the like. Data replica reservation receiving unit 0213 that performs processing such as exchange of information regarding user data requests between a plurality of gateway servers 0107 in the system for information reception and pre-creation of data replicas, operation of user programs Data access accepting unit 0214 that accepts access and data requests from the mobile terminal and the mobile unit 0106 of the user 0101 that is not always connected or the user 0101, obtains corresponding data from the data storage area 0211, and returns a response, data request from the user Reservation list for There is a reservation list management unit 0216 to create and manage.

  Further, as other components, the node of the user program or the user 0101 that is not always connected is connected via the data storage area 0211, the data storage area management unit 0217 for managing the stored data in the area, and the communication medium 0202. There is a data communication unit 0218 that performs communication with a mobile terminal, a mobile unit 0106, and the like.

  In response to an instruction from the reservation receiving unit 0213, the reservation list management unit 0216 refers to the data storage area 0211 and creates advance information for a new user data request and registers it in the reservation list. At this time, in response to an instruction from the reservation list management unit 0216, the data storage area management unit 0217 responds to the user's data request by providing information such as the presence / absence of the request data in the data storage area 0211 and the storage location address. In the case where there is no corresponding data in the data storage area 0211, processing such as new addition is performed.

Further, the data storage area management unit 0217 generates a replica of the data, accesses another gateway server via the data communication unit 0218 in order to store and update in the data storage area 0221, and receives another gateway server. Get data managed by. When the data storage area management unit 0217 receives a data request for replica generation from another gateway server, the data storage area management unit 0217 retrieves the corresponding data from the data storage area 0211 and returns it. Further, the data storage area management unit 0217 performs processing such as update completion or deletion of the storage replica, change of the data source, etc. in accordance with a change in the state of the data request side or data source of the storage replica in the data storage area 0211.
The data access receiving unit 0214 writes the processing history information in the history storage area 0212 every time the access / data request receiving processing from the user is executed.

FIG. 3 is a schematic diagram of an information sharing method.
FIG. 3 is a diagram showing an outline of an information sharing method in the present embodiment when one or more networks are included and also include system components that are not always connected in a distributed system in which they are connected to each other. .

  Main system components include a network environment 0301 for sharing and distributing information by exchanging messages and the like, and a gateway server 0303 that is connected to the network environment 0301 and serves as a point of contact with other systems and dedicated networks. , 0304, 0305, 0306, 0307, equipment / PI / O0321 for providing data to the system according to the present embodiment via the gateway server 0305, 0306, 0307, the sensor 0322, the mobile unit 0323, the present embodiment There is a user 0302 who accesses the system and requests and obtains data.

  In addition, there are an authentication server 0331, a location management server 0332, and the like that can be used to identify the user 0302 and provide the identification information 0341 of the user 0302. The gateway servers 0303, 0304, 0305, 0306, and 0307 store various data, and manage data storage areas 0311, 0312, 0313, 0314, and 0315 for responding to requests from the user 0302. Here, in order to simplify the description, the data storage areas 0311, 0312, 0313, 0314, and 0315 will be described as performing the following operations directly.

  According to the present embodiment, when the authentication server 0331 or the location management server 0332 detects that the user 0302 has joined the system, the authentication server 0331 or the location management server 0332 notifies the identification information of the user 0302 in the system. . When the data storage areas 0311, 0312, 0313, 0314, 0315 in which the identification information is distributed in the system are received, the data storage areas 0311, 0312, 0313, 0314, 0315 may be requested by the user 0302. In order to create the replica, the replica creation information 0342 including the type of data to create the replica, the arrangement location, etc. is created based on the related information of the user 0302, and multicast transmission is performed in advance in the system.

  In the data storage areas 0311 and 0312 that have received the multicast replica creation information 0342, a request of the user 0302 is received from the received one or more replica creation information 0342 or the replica creation information 0342 generated in the local area. A suitable one is selected, and based on the selected replica creation information 0342, replicas 0316 and 0317 of data that the user 0302 may request are generated, stored, and updated in advance. The data storage area 0312 that actually received the request from the user 0302 immediately responds using the replica 0317 of the data.

  Further, regarding the replica 0317 created in the data storage area 0312, when the state on the data source side is changed (in FIG. 3, the mobile body 0323 as the data source is moved), the data storage area 0312 is the data for generating the replica 0317. Is changed according to the state (in FIG. 3, the data source is changed from the data accumulation area 0314 to the data accumulation area 0315), or the access timing to the data source is changed.

FIG. 4 is a configuration diagram of the data storage area.
FIG. 4 is a diagram showing a configuration of a data storage area for storing data replicas provided in a gateway server or the like in the distributed system according to the present embodiment.
Main components of the data storage area 0401 include a main area 0411, a spare area 0412, a pointer area 0413, and a reservation list 0414.

  The main area 0411 is an area in which data values of frequently requested data are mainly stored without duplication in the data accumulation area 0401. The data storage area management unit 0217 acquires a value from the data source of the data periodically or when the value changes, and stores a plurality of values of the data in the main area 0411 in time series. The spare area 0412 is an area for storing data values that may be requested without duplication. The data storage area management unit 0217 acquires values from other data storage areas that hold the data at a lower frequency than the main area 0411, and overwrites and holds only the latest value in the spare area 0412. The pointer area 0413 is an area for storing pointer information to data stored in the main area 0411 of another data storage area 0401.

  The data storage area management unit 0217 receives information on stored data that is periodically distributed from each data storage area 0401 in the information control system, and updates the pointer information stored in the pointer area 0413 in the area. . Note that the data accumulation area management unit 0217 refers to the information stored in this area and holds the corresponding data when the corresponding data does not exist in the main area 0411 and the spare area 0412 in response to a user request. Query 0401 to obtain data. The reservation list 0414 is an area for storing reservation entry information for a user data request.

  The data storage area management unit 0217 stores, for each user, information such as data requested by the user or data that may be requested by the user, information such as a time stamp, in the reservation list 0414. When the user actually accesses the data storage area 0401 and requests data, the data storage area management unit 0217 refers to the information about the user in the reservation list 0414 and returns the value of the corresponding data. Also, these pieces of information are generated in advance before access from the user occurs.

FIG. 5 is a diagram showing a main area and a spare area.
FIG. 5 is a diagram showing a main area and a spare area for storing data replicas in a data storage area in which data replicas are arranged in a gateway server or the like in the distributed system according to the present embodiment. is there.
Main components of the main area 0501 include a data name 0511, a data value 0512, a time stamp 0513, an update cycle 0514, a reference count 0515, a last reference time 0516, and data source information 0517.

  The data name 0511 stores the name of data accessible by the user in the system. The data value 0512 stores a data value corresponding to the name stored in the data name 0511. Here, the data name 0511 stores a plurality of values in time series. The number of stored values is determined for each system. In the time stamp 0513, the storage time of each value stored in the data value 0512 in the main area 0501 is stored correspondingly. In the update cycle 0514, a cycle in which a data value corresponding to the name stored in the data name 0511 is written in the data value 0512 is stored.

  The reference count 0515 stores the number of times the user has referred to the data value corresponding to the name stored in the data name 0511. The value stored in the item of the reference count 0515 is updated every time there is a data reference from the user. The last reference time 0516 stores the time when the user last referred to the data value corresponding to the name stored in the data name 0511. The value stored in the item of the final reference time 0516 is updated every time there is a data reference from the user.

  The data source information 0517 stores data source address information 0531 and attribute information 0532 as information related to the data source of the data corresponding to the name stored in the data name 0511. The address information 0531 stores information for accessing the data source when creating / updating a replica. The attribute information 0532 stores information such as the validity period of the data source and the movement route. The data storage area management unit 0217 refers to the attribute information 0532 to change the data source.

Main components of the spare area 0502 include a data name 0521, a data value 0522, a time stamp 0523, an update cycle 0524, a reference count 0525, a final reference time 0526, and data source information 0527.
The data name 0521 stores the name of the data that can be accessed by the user in the system, similar to 0511. The data value 0522 stores a data value corresponding to the name stored in the data name 0521. Here, only the latest value of the data value 0522 is overwritten. The time stamp 0523 stores the storage time of the value stored in the data value 0522 in the spare area 0502. In the update cycle 0524, a cycle in which a value of data corresponding to the name stored in the data name 0521 is written in the data value 0522 is stored. Here, it is assumed that the cycle of writing data in the spare area 0502 is larger than the cycle of writing data in the main area 0501.

  The reference count 0525 stores the number of times the user referred to the data value corresponding to the name stored in the data name 0521. The value stored in the item of the reference count 0525 is updated every time there is a data reference from the user. The last reference time 0526 stores the time when the user last referred to the data value corresponding to the name stored in the data name 0521. The value stored in the item of the final reference time 0526 is updated every time there is a data reference from the user.

  Data source information 0527 stores data source address information 0541 and attribute information 0542 as information related to the data source of the data corresponding to the name stored in the data name 0521. The address information 0541 stores information for accessing the data source when creating / updating a replica. The attribute information 0542 stores information such as the validity period of the data source and the movement route. The data storage area management unit 0217 refers to the attribute information 0542 to change the data source.

FIG. 6 is a diagram showing a pointer area and a reservation list.
FIG. 6 stores pointer information to data stored in another data storage area in a data storage area in which data replicas are provided in a gateway server or the like in the distributed system according to the present embodiment. It is a figure which shows the reservation area | region which describes the pointer area | region and the information regarding a user's data acquisition request.
The main components of the pointer area 0601 are a data name 0611 and data source information 0612.

  The data name 0611 stores the name of data accessible by the user in the system. The data source information 0612 stores the address of the data source and other attribute information as information related to the data source of the data corresponding to the name stored in the data name 0611. The value of the item of the data source information 0612 is updated when the data storage area management unit 0217 receives update information of stored data in each data storage area that is multicast transmitted from another data storage area.

The main components of the reservation list 0602 are identification information 0621, data name 0622, storage location 0623, and time stamp 0624.
The identification information 0621 stores user identification information transmitted from an authentication server in the information control system. The data name 0622 stores one or more names of data requested or possibly requested by the user corresponding to the identification information stored in the identification information 0621. The values of these data names 0622 are stored as a result of the processing shown in FIGS.

  The storage location 0623 stores information related to the storage location in each data storage area regarding the data corresponding to the name of each data stored in the data name 0622. Here, information of the storage location type 0641 in the main area or the spare area, the address 0642 in the storage location of the type 0641, and the size 0643 of the storage data in the storage location of the type 0641 are stored. The time stamp 0624 stores the time when the identification information stored in the identification information 0621 is registered in the reservation list 0602.

FIG. 7 is a sequence diagram of processing for arranging data replicas.
FIG. 7 shows a process of proactively arranging data replicas for a plurality of data storage areas arranged on a network in a distributed system including one or more networks connected to each other in the present embodiment. FIG.

  The main components of the process of placing this data replica are the user 0701 requesting data, an authentication server or location management for detecting the user 0701 joining the system in the information control system, etc. Other servers 0702 and one or more data storage areas in the information control system include a first data storage area 0703, a second data storage area 0704, and a third data storage area 0705. Here, in order to simplify the description, the first data storage area 0703, the second data storage area 0704, and the third data storage area 0705 will be described as performing the following operations directly.

  In step 0711, as an example, the user 0701 transmits an authentication request to the authentication server 0702. In step 0721, the authentication server or other server 0702 performs authentication of the user 0701 to identify the user. If authentication is established in step 0721, in step 0722, the authentication server 0702 generates identification information of the user 0701, and data storage areas (first data storage area 0703, second data storage area 0704, second data storage area) in the system are generated. 3 is transmitted to the data storage area 0705).

  The first data storage area 0703, the second data storage area 0704, and the third data storage area 0705 that have received the identification information multicast-transmitted in step 0722 are the same in step 0731, step 0741, and step 0751, respectively. Information related to the user 0701 corresponding to the identification information (past access history, etc.) is searched from within its own area.

  In step 0732, step 0742, and step 0752, each of the first data storage area 0703, the second data storage area 0704, and the third data storage area 0705 includes the relevant information of the user 0701. In this case, replica information for preparing a replica of the data in advance in response to the user's data request is created according to the processing flow shown in FIG. Here, the replica information is a list of data names, attribute information, and the like of data that the user 0701 may request. Based on this information, each data storage area generates a data replica.

  In step 0733, the data storage area (the first data storage area 0703 in FIG. 7) for which the replica information has been created by the above procedure is stored in the second data storage area 0704, the third data storage area 0704, the third data storage area 0704, and the third data storage area 0704 Multicast transmission to the data storage area 0705. In step 0734, step 0744, and step 0754, the first data storage area 0703 transmitted by multicast transmission and the data storage area (second data storage area 0704, third data storage area 0705) that received the replica information transmitted by multicast transmission. ) Determines replica information to be used for the user 0701.

  Here, in each data storage area, there is replica information created in its own area, and when replica information from another data storage area is also received, it is determined which replica information is used. In addition, there is no replica information created in its own area in each data storage area, and when one or more replica information is received from another data storage area, it is determined which replica information is used.

As determination criteria for determining replica information to be used in Step 0734, Step 0744, and Step 0754, newness of information, set priority order, and the like are referred to. In step 0735, step 0745, and step 0755, each data storage area (the first data storage area 0703, the second data storage area 0704, and the third data storage area 0705) is the same as step 0734, step 0744, and step 0754. On the basis of the replica information determined to be used in step 1, the generation of the replica of the data for the user 0701 corresponding to the identification information and the update of the replica value based on the update on the source side are started.
In step 0712, when the user 0701 requests data from the nearest data storage area (second data storage area 0704 in FIG. 7), a replica of the data prepared in advance as described above is used in step 0746. Then, a response is returned to the user 0701.

FIG. 8 is a flowchart of processing for determining the location of the replica and the type of data in the present embodiment.
In other words, FIG. 8 includes one or more networks, and when replicas of data are arranged in advance in a plurality of data storage areas arranged on a network in a distributed system to which they are connected to each other, replicas are arranged. It is a flowchart which shows the flow of the process which determines the location or range of a data storage area, and the kind of data which produces | generates a replica.

  In step 0801, the reservation receiving unit 0213 receives the user identification information from the authentication server or the location management server in the information control system via the data communication unit 0218. In step 0802, the data storage area management unit 0217 determines data to be subjected to replica creation for the user's data request. In step 0803, the data storage area management unit 0217 determines a range in which data for creating the replica is arranged. In step 0804, the data storage area management unit 0217 sends, via the data communication unit 0218, information related to the data for which the replica creation determined in 0802 is performed to the data storage area in the range determined in 0803 by multicast transmission. .

  Hereinafter, a flow of processing in the determination processing of replica execution data in the step 0802 will be shown. In step 0821, the reservation receiving unit 0213 makes an inquiry to the data storage area management unit 0217 to determine whether or not there is reservation information that specifies the type and item of data requested by the user together with the user identification information. to decide. If there is reservation information in step 0821, in step 0824, the reservation receiving unit 0213 determines that the data for which the replica is to be created is the type / item data specified in the reservation information.

  If there is no reservation information in step 0821, in step 0822, the reservation receiving unit 0213 refers to the history storage area 0212 and determines whether or not there is a user access history corresponding to the identification information. If there is an access history in step 0822, in step 0825, the data storage area management unit 0217 extracts data that has been referred to before from the access history, and determines that the data is to be subjected to replica creation.

  In step 0822, if there is no access history, in step 0823, the reservation receiving unit 0213 makes an inquiry to the reservation list management unit 0216, and whether there is business information of the user corresponding to the identification information along with the identification information. Judge whether or not. If there is business information or the like in step 0823, in step 0826, the reservation receiving unit 0213 extracts data related to the business and determines it as data for which replica creation is performed. If there is no business information in step 0823, in step 0827, the reservation receiving unit 0213 does not specify any data for replica creation.

  In the following, a flow of processing in the determination processing of the replica arrangement range in step 0803 will be shown. In step 0831, the reservation receiving unit 0213 makes an inquiry to the reservation list management unit 0216 to determine whether there is schedule information with the user's work corresponding to the identification information as well as the identification information. If there is schedule information or the like in step 0831, in step 0834, the reservation receiving unit 0213 refers to the schedule information and determines the scheduled action range of the user as a replica arrangement range.

  In step 0831, when there is no schedule information or the like, in step 0832, the reservation receiving unit 0213 makes an inquiry to the reservation list management unit 0216, and whether there is location information of the user corresponding to the identification information together with the identification information. Judge whether or not. If there is position information in step 0832, in step 0835, the reservation receiving unit 0213 determines the range around the user as the replica arrangement range.

  If there is no position information in step 0832, in step 0833, the reservation receiving unit 0213 makes an inquiry to the data access receiving unit 0214, and the history of the user's data reference location corresponding to the identification information is stored together with the identification information. Judge whether or not there is. If there is history information in step 0833, in step 0836, the reservation receiving unit 0213 determines the location where the data with the history is referred to as the replica arrangement range.

  If there is no history information in step 0833, in step 0837, the reservation receiving unit 0213 determines the entire system as the replica arrangement range. However, when replicas are arranged in the entire system, responsiveness to user data requests can be guaranteed, but the communication load and processing load of each data storage area also increase, and there is a possibility that the performance of the entire system may be reduced. When the arrangement range of replicas is limited by Step 0831, Step 0832, and Step 0833, the performance of the entire system can be maintained.

FIG. 9 is a flowchart of access processing from a terminal in the present embodiment.
That is, FIG. 9 shows a case in which the nearest data storage area is accessed from a node where a user program operates or a user's mobile terminal that is not always connected in a distributed system in which one or more networks are included and connected to each other. It is a flowchart which shows the flow of a process by the side of a user.

  In step 0901, the node on which the user program operates or the mobile terminal of the user who is not always connected determines whether authentication is necessary in the application destination system. If authentication is required in step 0901, in step 0902, authentication is requested to the authentication server in the information control system from the node where the user program is operated or the mobile terminal of the user who is not always connected.

  In step 0903, the node on which the user program operates or the mobile terminal of the user who is not always connected terminates the process if authentication is not established in response to the authentication request. In step 0903, the node on which the user program operates or the mobile terminal of the user who is not always connected determines whether or not authentication is established in response to the authentication request. If authentication is established in step 0903, in step 0904, the node on which the user program operates or the user's mobile terminal that is not always connected starts processing for accessing the data storage area and acquiring data in the present embodiment. .

  In step 0905, the nearest data storage area is searched from the node where the user program operates or the mobile terminal of the user who is not always connected. Here, if it is a data storage area in a gateway server in the same segment, or a mobile terminal of a user who performs short-range wireless communication, the data in the gateway server in the same segment as the nearest access point with strong signal strength The accumulation area or the like is a search target. In step 0906, the user's mobile terminal accesses the nearest data storage area found and requests data. In step 0907, the user's mobile terminal acquires the data requested in step 0906.

FIG. 10 is a flowchart of processing for a data request in this embodiment.
That is, FIG. 10 is a flowchart showing a flow of processing on the data storage area side in response to an access data request from the user side in a distributed system including one or more networks and interconnecting them.

  In step 1001, the data access receiving unit 0214 receives a data request from a user or a user program in the information control system via the data communication unit 0218. In step 1002, the data access receiving unit 0214 determines whether the identification information specified by the authentication server or the location management server matches the identification information extracted from the data storage area 0401.

  If the identification information matches in step 1002, in step 1003, the data access receiving unit 0214 searches for the corresponding data in the request from the main area 0411 in the data storage area 0401. In step 1004, the data access receiving unit 0214 determines whether the main area 0411 has corresponding data. In 1004, when there is relevant data in the main area 0411, in 1005, the data access receiving unit 0214 acquires the relevant data from the main area 0411.

  If there is no corresponding data in step 1004, in step 1006, the data access receiving unit 0214 searches the spare area 0412 in the data storage area 0401 for the corresponding data corresponding to the request. In step 1007, the data access receiving unit 0214 determines whether there is corresponding data in the spare area 0412. If there is relevant data in step 1007, in step 1008, the data access receiving unit 0214 obtains the relevant data from the spare area 0412.

  In step 1007, if there is no corresponding data in the spare area 0412, in 1009, the data access receiving unit 0214 searches the pointer area 0413 in the data storage area 0401 for the corresponding data for the request. In step 1010, the data access receiving unit 0214 determines whether or not there is information regarding the corresponding data in the pointer area 0413. If there is information on the corresponding data in step 1010, in step 1011, the data access receiving unit 0214 obtains information on the corresponding data from the pointer area 0413, and transmits a data request to the data storage area 0401 holding the corresponding data. To do. In step 1012, the data access receiving unit 0214 acquires the data.

  In step 1013, the data access receiving unit 0214 determines whether or not the search for all data in the data request from the user has been completed. If all of the requested data is completed in step 1013, the process is terminated. If it is determined in step 1013 that the search for all data in the data request from the user has not been completed, the process returns to step 1003 and the processes from step 1003 to step 1012 are repeated.

FIG. 11 is a flowchart of data update and deletion processing in the present embodiment.
That is, FIG. 11 is a flowchart showing the flow of processing for updating and deleting data stored in various tables in the data storage area provided in the gateway server or the like in the distributed system.

  In step 1101, the data storage area management unit 0217 refers to the reference count item (0525 in FIG. 5) and the last reference time item (0526 in FIG. 5) in the spare area 0412 in the data storage area 0401, Extract data with low reference frequency. In step 1102, the data storage area management unit 0217 determines whether or not each data extracted in step 1101 matches a threshold condition. The threshold here is, for example, a lower limit value of the data reference count or an upper limit value of the elapsed time from the last reference time, and a specific value is determined for each system.

  If the condition is met in step 1102, the data storage area management unit 0217 deletes the extracted data from the spare area in step 1103. If the condition is not met in step 1102, the data storage area management unit 0217 does not perform processing. In step 1104, the data storage area management unit 0217 refers to the item of reference count (0525 in FIG. 5) and the item of last reference time (0526 in FIG. 5) in the spare area 0412 in the data storage area 0401, Extract data with high reference frequency.

  In step 1105, the data storage area management unit 0217 determines whether or not each data extracted in step 1104 matches a threshold condition. The threshold here is, for example, the upper limit value of the data reference count or the lower limit value of the elapsed time from the last reference time, and a specific value is determined for each system. If the condition is met in step 1105, the data storage area management unit 0217 moves the extracted data to the main area 0411 in the data storage area 0401 in step 1106.

  In step 1105, if the conditions do not match, the data storage area management unit 0217 does not perform processing. In step 1107, the data storage area management unit 0217 refers to the item of reference count (0515 in FIG. 5) and the item of last reference time (0516 in FIG. 5) in the main area 0411 in the data storage area 0401, Extract data with low reference frequency.

  In step 1108, the data storage area management unit 0217 determines whether or not each data extracted in step 1107 meets the threshold condition. The threshold here is, for example, a lower limit value of the data reference count or an upper limit value of the elapsed time from the last reference time, and a specific value is determined for each system. If the condition is met in step 1108, the data storage area management unit 0217 moves the extracted data to the spare area 0412 in the data storage area 0401 in step 1109.

  In step 1108, if the conditions do not match, the data storage area management unit 0217 does not perform processing. In step 1110, the data storage area management unit 0217 multicasts information related to data newly stored in the main area 0411 and information related to data deleted from the main area 0411 to another data storage area 0401.

  The above processing is performed periodically, data with a high reference frequency is always stored in the main area 0411, data with a relatively high reference frequency is stored in the spare area 0412, and data with a low reference frequency is deleted from the data storage area 0401. To do. In this way, each data storage area 0401 can be kept ready for user request data.

FIG. 12 is a flowchart of the data source change process in the present embodiment.
That is, FIG. 12 is a flowchart showing a flow of processing when a data source of a replica of data arranged in a data storage area in a distributed system including one or more networks and connected to each other is changed. It is.

  In step 1201, the data storage area management unit 0217 receives update information related to the data source of the replica stored in the data storage area 0401 by a message or the like. In step 1202, the data storage area management unit 0217 determines whether or not the update information includes schedule information related to the operation of the data source.

  If it is determined in step 1202 that the schedule information related to the operation of the data source or the like, or the route information or the like is included in the update information of the data source if the data source is a mobile object, in step 1203 With reference to schedule information, route information, and the like, a data source that is accessible from the data storage area 0401 in which the replica is placed is selected from the scheduled operation range of the data source, and is set as a new data source.

  If the update information does not include schedule information, route information, etc. regarding the data source in step 1202, in step 1204, the data storage area management unit 0217 determines whether there is location information of the data source corresponding to the update information. Determine whether. If the location information of the data source is included in the update information of the data source in step 1204, in step 1205, the data storage area management unit 0217 determines the data storage area from the peripheral area of the data storage area 0401 in which the replica is placed. An accessible one is selected from 0401 and set as a new data source.

  If the data source location information or the like is not included in the update information of the data source in step 1204, the data storage area management unit 0217 sets the data source unchanged in step 1206. In step 1207, the data storage area management unit 0217 stores the data storage item 0401 in the data storage area 0401 in which the replica is arranged, in the item relating to the data source of each data in the main area or the spare area shown in FIG. Updated information.

FIG. 13 is a diagram showing a message format transmitted and received for information sharing in the present embodiment.
That is, FIG. 13 is a diagram showing a format of a message that is transmitted and received in order to share information related to stored data among the respective data storage areas provided in a gateway server or the like in the distributed system.
The main components of the message shown in FIG. 13 are header information 1301, source data storage area information 1302, number of newly added data 1303, number of deleted data 1304, number of update data 1305, new added data information 1306, Deleted data information 1307 and updated data information 1308.

  The header information 1301 stores information related to the message protocol and the like. The information 1302 of the data storage area of the transmission source stores information such as the address of the data storage area of the transmission source. The number of newly added data 1303 stores the number of data newly added by the update process of the main area of the data accumulation area. The number of deleted data 1304 stores the number of data deleted by the update process of the main area of the data storage area. The number of updated data 1305 stores the number of data whose attribute information has been updated in accordance with the change in the state of the data source.

  The newly added data information 1306 stores information related to newly added data by the update process of the main area of the data accumulation area, and stores data name 1361 and attribute information 1362 for each data. The attribute information 1362 includes information on the data source attribute, status, etc., in addition to the data size, update cycle, and the like. The number of combinations of the data name 1361 and the attribute information 1362 is stored in the number stored in the number of newly added data 1303. When the number stored in the number of newly added data 1303 is 0, the newly added data information 1306 is not included in the message.

  In the deletion data information 1307, information on data deleted by the update process of the main area of the data storage area is stored, and the name 1371 of the data to be deleted is stored as many as the number stored in the deletion data number 1304. Has been. If the number stored in the number of deleted data 1304 is 0, the deleted data information 1307 is not included in the message.

  The updated data information 1308 stores information related to data whose attribute information has been updated in accordance with a change in the state of the data source, and stores a data name 1381 and updated attribute information 1382 for each data. The combination of the data name 1381 and the attribute information 1382 includes information on the attribute and state of the updated data source. In the updated attribute information 1382, the number of update data 1305 is stored. When the number stored in the number of update data 1305 is 0, the update data information 1308 is not included in the message.

FIG. 14 is a configuration diagram of a field work support system for utility pole maintenance / equipment maintenance in the present embodiment.
That is, FIG. 14 is a diagram illustrating an example in which the information sharing method in the distributed system is applied to an on-site work support system for maintenance / maintenance for power pole maintenance personnel who are facilities of a power company.

  In the field work support system shown in FIG. 14, a base 1403 and substations 1404 and 1405 are interconnected via a power company communication network 1406. The substation 1404 is connected to a network of utility poles 1421 distributed in the area. The substation 1405 is connected to a network of a plurality of power line facilities 1422 installed in mountainous areas. In addition, work such as maintenance inspection and maintenance is performed on the electric pole 1421 in the area by a maintenance work vehicle 1401 that patrols. Maintenance staff 1402 visits the power line equipment 1422 installed in the mountainous area and performs operations such as maintenance inspection and maintenance.

  Main components of the on-site work support system shown in FIG. 14 are utility pole servers 1431, 1432, 1433, power line equipment that are installed on the utility pole 1421, manage the equipment mounted on the utility pole, and communicate with the maintenance work vehicle 1401. 1422 installed on each of the power line equipment servers 1441, 1442, 1443, 1444, the base 1403, the substations 1404, 1405, etc. that manage the power line equipment and communicate with the mobile terminal of the maintenance personnel 1402. There are gateway servers 1411, 1412, 1413, etc. that connect the communication network 1406 of the electric power company and the network in each base. The gateway servers 1411, 1412, 1413, utility pole servers 1431, 1432, 1433, and power line equipment servers 1441, 1442, 1443, 1444, etc. have managed data storage areas for placing data replicas according to this embodiment. Yes.

  In this system, when a maintenance worker 1402 patrols the electric pole 1421 in the area with the maintenance work vehicle 1401 to inspect the electric pole 1421 and visually inspects the electric pole 1421 from the car, the maintenance work vehicle 1401 is removed. The wireless terminal mounted on the maintenance work vehicle 1401 acquires data from each power pole 1421 when passing through each power pole 1421 without stopping. Here, there is no need to stop and work for each power pole in order to acquire data, leading to reduction in work load and efficiency. The acquired data can be used for preventive maintenance of the utility pole 1421.

  In order to improve the reliability and quality of maintenance work and maintenance work, the maintenance work vehicle 1401 includes facility information held by the servers 1431, 1432, and 1433 of each power pole 1421 (voltage values of transformers, temperatures, strain sensors). Not only the current value of the value or gas insulator gas concentration, pressure value, etc., but also the asset information of each facility, inspection history (managed by the asset management server 1451 and maintenance management server 1452 in the base 1403), etc. Refer to it.

  In addition, the maintenance work vehicle 1401 compares and refers to the facility information of the adjacent utility pole 1421. Therefore, based on the inspection route plan of the maintenance work vehicle 1401 and the current position information of the maintenance work vehicle 1401 measured using GPS (global positioning system) or the like, the maintenance work vehicle 1401 arrives near each power pole 1421. In advance, the utility pole servers 1431, 1432, and 1433 create and store the necessary data replicas in the data storage area to be managed. When the maintenance work vehicle 1401 approaches each power pole 1421 and accesses the power pole servers 1431, 1432, 1433, the power pole servers 1431, 1432, 1433 immediately respond using the data in the data storage area.

  Similarly, the maintenance staff 1402 also performs maintenance and maintenance work for the power line equipment 1422 installed in the mountainous area, but works close to each power line equipment 1422 like the maintenance and maintenance of the power pole 1421, and data It is difficult to get. Therefore, in the mountainous area, power line equipment servers 1442, 1443, and 1444 installed in the power line equipment 1422 installed in places (such as in the middle of the mountain, near the summit, etc.) where it is particularly burdensome for the maintenance personnel 1402 to approach and work. The power line equipment server 1441 of the power line equipment 1422 in the place near the foot of the mountain and where it is easy for the maintenance staff 1402 to approach and work is collectively stored.

  The storage of data by the power line equipment server 1441 is based on the maintenance staff 1402 arriving near the power line equipment server 1441 based on the work schedule of the maintenance staff 1402 and the current position information of the maintenance staff 1402 measured using GPS or the like. Also go in advance. As described above, the maintenance staff 1402 can immediately obtain information on all the facilities scattered in the mountainous area and related information with a low load by accessing only one of the easily accessible power line equipment servers 1441.

FIG. 15 is a configuration diagram of a vehicle-to-ground communication system for wireless communication between a train and a wireless station in the present embodiment.
That is, FIG. 15 is a diagram illustrating an example in which the information sharing method in the distributed system is applied to an on-vehicle communication system that performs wireless communication between a traveling train and a wireless station installed along a track. is there.

  In the on-vehicle communication system shown in FIG. 15, the relay stations 1504 and 1505 and the relay stations 1504 and 1505 installed at a plurality of locations on the bases 1502 and 1503 and the track via the communication network 1506 of the railway company. A traveling train 1501 that performs communication using a wireless device 1521 is interconnected via wireless base stations 1522, 1523, 1524, and 1525 that are installed on the track at regular intervals.

  The main components of the on-vehicle communication system shown in FIG. 15 are an authentication server 1531 that is connected to a communication network 1506 of a railway company and issues and distributes authentication and identification information of users and trains. Gateway servers 1511, 1512, 1513, which are installed at each base such as the business server 1532 to be managed, the bases 1502 and 1503, and the relay stations 1504 and 1505, and connect the communication network 1506 of the railway company and the networks in each base, 1514 etc. The gateway servers 1511, 1512, 1513, 1514, etc. manage data storage areas for placing data replicas according to this embodiment.

In this system, maintenance and maintenance of the facilities of the train 1501 are performed by the gateway servers 1513 and 1514 in the nearest relay stations 1504 and 1505 collecting and analyzing in real time the facility information during the traveling of the train 1501 via wireless communication. To help.
The traveling train 1501 transmits equipment information using the wireless device 1521. However, since the short-range wireless is used, only the nearest wireless base station can receive the information. In FIG. 15, when the radio base station 1522 or 1523 receives real-time facility information of the train 1501 transmitted from the radio device 1521 of the running train 1501, it is managed by the gateway server 1513 in the relay station 1504. The facility information received from the train 1501 is stored in the data storage area.

  When the radio base station 1524 or 1525 receives the facility information of the train 1501 transmitted from the wireless device 1521, the facility received from the train 1501 in the data storage area managed by the gateway server 1514 in the relay station 1505. Information is accumulated. As the train 1501 travels in this way, the facility information of the train 1501 is collected and accumulated by being divided into each relay station installed at a plurality of locations on the track.

  However, for example, when the user uses the terminal 1542 of the base 1503 to monitor the facility information of the running train 1501, after the user authentication processing is performed by the authentication server 1531 installed in the base 1502, A replica of the facility information data of the running train 1501 that is distributed and stored in each of the relay stations 1504 and 1505 is managed by the gateway server 1512 nearest to the terminal 1542 used by the user. It is generated and stored in the data storage area and is updated as the train 1501 travels.

  At this time, a replica of data such as asset information related to the facilities of the train 1501 managed by the business server 1532 in the base 1502 is also stored in the data storage area managed by the gateway server 1512 according to business needs. Generated.

  Although the embodiments of the present invention have been specifically described above, the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

It is a block diagram of the information sharing system by this Embodiment. It is a block diagram of a gateway server. It is a schematic diagram of an information sharing method. It is a block diagram of a data storage area. It is a figure which shows the main area | region and a reserve area | region. It is a figure which shows a pointer area | region and a reservation list. It is a sequence diagram of a process for arranging a replica of data. It is a flowchart of the process which determines the arrangement | positioning location of a replica, and the kind of data. It is a flowchart of the access process from a terminal. It is a flowchart of the process with respect to a data request. It is a flowchart of the process of update and deletion of data. It is a flowchart of the process of a data source change. It is a figure which shows the format of the message transmitted / received for information sharing. It is a block diagram of the field work support system for utility pole maintenance and equipment maintenance. 1 is a configuration diagram of an on-vehicle communication system for radio communication between a train and a radio station.

Explanation of symbols

  0101 ... User, 0102 ... First base, 0103 ... Second base, 0104 ... Factory, 0105 ... Communication network, 0106 ... Mobile, 0107 ... Gateway server, 0108 ... Equipment / device, 0109 ... Sensor tag, 0110 ... Authentication server, 0111 ... Fixed terminal, 0121 ... Processing device, 0122 ... Communication device, 0123 ... Storage device, 0124 ... Data storage area, 0122 ... Communication device, 0131 ... Wireless base station, 0201 ... Middleware, 0211 ... Data storage area , 0212 ... History storage area, 0213 ... Reservation reception part, 0214 ... Data access reception part, 0216 ... Reservation list management part, 0217 ... Data storage area management part, 0218 ... Data communication part

Claims (8)

An information sharing method in a distributed system for sharing information between a data source and a data requesting side that are always connected or not always connected to a network of a distributed system in which one or more networks are connected to each other,
A replica for searching for information related to the identification information of the data requester from a data storage area distributed in the system and creating a replica including the type and location of data based on the related information Creating creation information;
The replica creation information is shared among one or more data storage areas within the range designated as the replica placement location, and includes the replica creation information created for the data requester. Selecting one suitable for the data request from the creation information, and creating a replica of the data in the data storage area in advance based on the selected replica creation information;
If there is an access from the data requesting side corresponding to the identification information, returning a response using a replica of the data from the data storage area;
According to the state of the replica on the data source side, changing the data source for generating the replica or the placement of the replica;
There is no reference after a certain period of time or a replica of data with low reference frequency is deleted from the data storage area;
When creating replica creation information for generating a replica of data that may be requested by the data requesting side, refer to the access history of the data requesting side and extract data with a past reference To determine the type of data for creating the replica ;
An information sharing method in a distributed system, comprising: In the information sharing method in the distributed system of Claim 1,
When creating replica creation information for generating a replica of data that may be requested by the data requesting side, refer to schedule information related to the data requesting side and based on a scheduled action range of the data requesting side A method for sharing information in a distributed system, comprising the step of determining an arrangement location of the replica. In the information sharing method in the distributed system of Claim 1,
When creating replica creation information for generating a replica of data that may be requested by the data requesting side, refer to the location information of the data requesting side, and from the range around the current location of the data requesting side A method for sharing information in a distributed system, comprising the step of determining an arrangement location of the replica. In the information sharing method in the distributed system of Claim 1,
When creating replica creation information for generating a replica of data that may be requested by the data requesting side, refer to the access history of the data requesting side, based on the location where there is a past reference record, An information sharing method in a distributed system, comprising a step of determining an arrangement location of a replica. In the information sharing method in the distributed system of Claim 1,
The data requesting side to which the identification information has been distributed includes a step of accessing the nearest data storage area from a node operating on the data requesting side and acquiring data when requesting data. Information sharing method in the system. In the information sharing method in the distributed system of Claim 1,
When changing the data source for generating the replica, refer to schedule information and route information related to the data source, select a data source accessible from the data storage area, and access to the data source An information sharing method in a distributed system, comprising a step of determining time, frequency, and the like. In the information sharing method in the distributed system of Claim 1,
When the data source for generating the replica is changed, the data source is selected from the surroundings of the data storage area by referring to the location information or the survival signal of the data source, and the data source An information sharing method in a distributed system, comprising the step of determining an access time and frequency of access to the system. In the information sharing method in the distributed system of Claim 1,
A distributed system comprising a step of deleting information relating to the data requesting side from a reservation list in the data storage area when there is no access from the data requesting side corresponding to the identification information even after a certain period of time has elapsed. Information sharing method.

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