Abstract: In an architecture including a plurality of sub-application units and a plurality of CC-OCCs (Client-Coordinated transaction managers that perform Optimistic Concurrency Control) included in a plurality of data source client systems, consistency of a plurality of snapshots managed by a plurality of CC-OCCs is maintained for each transaction. With respect to each transaction, when the number of CC-OCCs which receive a read request and/or a write request for an object from two or more sub-application units in processing of M-number of (where M is an integer of 2 or more) sub-transactions that constitute the transaction is N (where N is an integer of 2 or more), N-number of unions are pairwise disjoints. With respect to each of the N-number of unions, the union is a union of a read set and a write set in a snapshot which corresponds to the transaction and which is managed by a CC-OCC.

Abstract: When a controller of a client server updates component data D12 to component data D13, the controller creates in a distributed ledger which is a first proof chain, a record (Age [3]) including a hash value of the component data D13. Then, the controller generates a terminal hash value which is a hash value of a terminal record (Age [3]) in the first proof chain. The controller has the generated terminal hash value stored in a record in a distributed ledger which is a second proof chain, and associates the first proof chain and the second proof chain with each other.

Abstract: A data management system receives a status update request in which a target is specified and executes status update processing of updating a status of the target specified in the status update request. The status update processing includes transaction processing that is processing of updating first information and second information in an ACID (Atomicity, Consistency, Isolation, Durability) transactional manner. The first information is a first object group (one or more first objects) for each target. The first object is data that represents the status of the target. The second information is a second object group (one or more second objects) for each target. The transaction processing includes first processing of creating, updating, or deleting the first object corresponding to the specified target, and second processing of adding the second object including at least one of a content of the first processing and a summary of the first object to the second object group corresponding to the specified target.

Abstract: A context that is a description for identifying one or more targets is added to a state update request. The status update request is issued by a first computer system and input to an ordering system. For each node system in a second computer system that communicates with one or a plurality of first computer systems and includes a plurality of node systems, each time a state update request is output from the ordering system, one or more targets are identified from the context of the state update request. When the identified one or more targets do not conflict with one or more targets specified in one or more status update requests being executed in the node system, the status update request is executed in the node system.

Abstract: A node system of a second computer system executes processing of updating a state of a target specified in a request from a first computer system, and in the executing, adds an object to an asset for the target in an asset set. The object is data that represents the state of the target. The asset is assigned to each target and is a time series of objects. The asset set is a set of assets and has a DAG structure. A node is the object and an edge represents a relationship between objects. The added object is a terminal object. The node system outputs a proof of existence that is the terminal object or a summary thereof, and the proof of existence is saved in an external system managed by a management entity different from a management entity for the node system.

Abstract: A device includes: a storage storing a distributed ledger, the distributed ledger including a plurality of evidence chains and a time stamp chain, the plurality of evidence chains storing in chronological order at least one hash value, the time stamp chain storing in chronological order at least one time stamp token; and a processor configured to repeatedly execute an update process such that the time stamp chain is updated, the update process including a process for identifying, out of the evidence chains, at least one evidence chain in which the hash value has been changed with a change in the file since previous execution of the update process, and acquiring the time stamp token for a terminal value generated based on a terminal hash value of the at least one evidence chain.

Abstract: When a second operation to simultaneously update component data D12 to component data D13 and update component data D21 to component data D22 is performed, a controller of a client server creates a record RA3 including a hash value of the component data D13 in a distributed ledger which is a first proof chain and creates a record RB2 including a hash value of the component data D22 in a distributed ledger which is a second proof chain. The controller generates a terminal hash value including a record hash value of the record RA3 and a record hash value of the record RB2 and obtains a time stamp token for the terminal hash value.

Abstract: As a record RA1 is stored in a first distributed ledger, a controller of a client server obtains a time stamp token T0 for a record hash value RH1 thereof and has a record RB0 including the time stamp token T0 stored in a second distributed ledger. Then, as a record RA2 is stored in the first distributed ledger, the controller obtains a time stamp token T1 for a record hash value RH2 of the record RA2. Then, the controller has a record RB2 including the time stamp token T1 and a record hash value of the record RB0 stored in the second distributed ledger.

Abstract: In each node system, a request execution unit executes, for each state update request, state update processing of updating an object representing a state of a target specified in the request, and returns a response indicative of completion of the request without executing tamper-evidence processing. The tamper-evidence execution unit executes tamper-evidence processing of detecting whether one or more common completion requests of one or a plurality of update completion requests are tampered with by comparing updated objects of two or more node systems or summaries thereof. The update completion request is a state update request for which the execution of the state update processing has been completed. The common completion request is an update completion request that is common among two or more node systems of the plurality of node systems.

Abstract: When a controller of a client server updates component data D12 to component data D13, the controller creates in a distributed ledger which is a first proof chain, a record (Age [3]) including a hash value of the component data D13. Then, the controller generates a terminal hash value which is a hash value of a terminal record (Age [3]) in the first proof chain. The controller has the generated terminal hash value stored in a record in a distributed ledger which is a second proof chain, and associates the first proof chain and the second proof chain with each other.