384 | Data Model
385 |
386 |
387 | To provide the greatest amount of flexibility, the data model is a graph.
388 | If a formalized data model is desired, RDF may be utilized but is not necessary.
389 |
390 |
391 |
392 | To ensure that the syntax will be easily adopted by developers, and supports
393 | a graph-based data model, it is RECOMMENDED that the implementation syntax is
394 | JSON-LD (or similarly compatible syntax). Other RDF-compatible syntaxes MAY
395 | also be used to express the ledger semantics. This ensures that the syntax is
396 | processable by widely adopted JSON tooling while also ensuring that the
397 | data model is robust enough to handle decentralized extensibility without
398 | name clashes or conflicts.
399 |
400 |
401 |
402 | A ledger consists of a series of entries. This section outlines the basic
403 | types of entries that all Web Ledgers support. A particular Web Ledger MAY
404 | contain more than these basic entries.
405 |
406 |
407 |
408 | Blocks
409 |
410 |
411 | A block contains one or more changes to the state machine.
412 | Blocks are typically used as a storage optimization to bundle a set of
413 | changes to the state machine. There can be many types of blocks.
414 | This specification details the basic set of blocks that all Web Ledgers
415 | may express.
416 |
417 |
418 |
419 |
420 |
421 | Configuration Block
422 |
423 |
424 | A configuration block specifies which software algorithms should be applied
425 | when processing a particular Web Ledger. The first entry in a Ledger is
426 | typically an entry called a genesis block. The genesis block has the
427 | following basic layout:
428 |
429 |
430 |
431 | {
432 | "@context": "https://w3id.org/web-ledger/v1",
433 | "id": BLOCK_ID,
434 | "type": "LedgerConfigurationBlock",
435 | "ledgerConfig": {
436 | "id": LEDGER_ID,
437 | "type": "LedgerConfiguration",
438 | "name": "example",
439 | "description": "This is an example ledger.",
440 | "storageMechanism": STORAGE_DATA_STRUCTURE,
441 | "consensusAlgorithm": CONSENSUS_ALGORITHM,
442 | "previousBlock": {
443 | "hash": "urn:sha256:0000000000000000000000000000000000000000000000000000000000000000"
444 | },
445 | "signature": SIGNATURE_VALUE
446 | }
447 |
448 |
449 |
450 | In the example above, LEDGER_ID is used to uniquely identify the
451 | ledger (e.g. did:f6ea280f-8011-4502-a29f-464954de3427).
452 | BLOCK_ID is used to uniquely identify the block in the ledger
453 | (e.g. did:f6ea280f-8011-4502-a29f-464954de3427/blocks/1.
454 | STORAGE_DATA_STRUCTURE is used to identify the storage mechanism
455 | that is used in the ledger (e.g. SequentialList) so that
456 | serializing and
457 | deserializing the contents of the ledger remains consistent across ledgers.
458 | SIGNATURE_VALUE is used to perform the cryptographic proof that
459 | the ledger block was created by the entity identified in the signature. A more
460 | complete example of a genesis block is
461 | available in the appendix.
462 |
463 |
464 |
465 | A standard configuration block update only differs from a genesis block in
466 | that the previousBlock value refers to the block before the
467 | current block:
468 |
469 |
470 |
471 | {
472 | "@context": "https://w3id.org/web-ledger/v1",
473 | "id": BLOCK_ID,
474 | "type": "LedgerConfigurationBlock",
475 | "ledgerConfig": {
476 | "id": LEDGER_ID,
477 | "type": "LedgerConfiguration",
478 | "name": "example",
479 | "description": "This is an example ledger.",
480 | "storageMechanism": STORAGE_DATA_STRUCTURE,
481 | "consensusAlgorithm": CONSENSUS_ALGORITHM,
482 | "previousBlock": {
483 | "id": PREVIOUS_BLOCK_ID,
484 | "hash": PREVIOUS_BLOCK_HASH
485 | },
486 | "signature": SIGNATURE_VALUE
487 | }
488 |
489 |
490 |
491 | The PREVIOUS_BLOCK_ID is the identifier of the previous
492 | block in the ledger (e.g.
493 | did:f6ea280f-8011-4502-a29f-464954de3427/blocks/1) and the
494 | PREVIOUS_BLOCK_HASH value (e.g.
495 | urn:sha256:abd465d34f7a3f0f7d849550eb9fc32c17d12881da6b524da0a96e12cc984538
496 | is a hash of the previous block in the ledger.
497 |
498 |
499 |
500 |
501 |
502 | Storage Block
503 |
504 |
505 | A storage block stores data in a ledger and has the following general layout:
506 |
507 |
508 |
509 | {
510 | "@context": ["https://w3id.org/web-ledger/v1", MARKET_VERTICAL_CONTEXT],
511 | "id": BLOCK_ID,
512 | "type": "LedgerStorageBlock",
513 | "setObject": [ OBJECTS ],
514 | "previousBlock": {
515 | "id": PREVIOUS_BLOCK_ID
516 | "hash": PREVIOUS_BLOCK_HASH
517 | },
518 | "signature": SIGNATURE_VALUE
519 | }
520 |
521 |
522 |
523 | When storing data in the ledger, one may use a
524 | MARKET_VERTICAL_CONTEXT to add semantics to the objects stored in
525 | OBJECTS
526 | (e.g. https://w3id.org/vaccinations/v1).
527 | OBJECTS are one or more JSON objects that can be stored in
528 | the ledger. It is expected that each object has a unique identifier to
529 | enable searching based on that identifier. A detailed
530 | example of a storage event is included in
531 | the appendix.
532 |
533 |
534 |
535 |
536 |
537 | Consensus Block
538 |
539 |
540 | It's currently not specified in a configuration event how often consensus
541 | events should occur. The options are: per event, or every N events. This is
542 | an active area of research and debate.
543 |
544 |
545 |
546 | A consensus event is an assertion that there is agreement on a subset of entries
547 | in a ledger. Some ledgers do not require consensus events as each event
548 | establishes an acceptable level of consensus. Other ledgers require consensus
549 | events after a pre-determined amount of time. An example of the basic layout
550 | of a consensus event is shown below:
551 |
552 |
553 |
554 | {
555 | "@context": "https://w3id.org/web-ledger/v1",
556 | "id": BLOCK_ID,
557 | "type": "ConsensusBlock",
558 | "previousBlock": {
559 | "id": PREVIOUS_BLOCK_ID
560 | "hash": PREVIOUS_BLOCK_HASH
561 | },
562 | "signature": [ SIGNATURES ]
563 | }
564 |
565 |
566 |
567 | A consensus event has a relatively simple definition. It consists of a
568 | number of SIGNATURES from notaries as determined by the previous
569 | configuration event. A more complete
570 | example of a consensus event
571 | is located in the appendix.
572 |
573 |
574 |
575 |
576 |
577 | Checkpoint Block
578 |
579 |
580 | A checkpoint event may be used to quickly bootstrap new mirrors for a ledger.
581 | An example of the basic layout of a checkpoint event is shown below:
582 |
583 |
584 |
585 | {
586 | "@context": "https://w3id.org/web-ledger/v1",
587 | "id": BLOCK_ID,
588 | "type": "LedgerCheckpointBlock",
589 | "checkpointLog": CHECKPOINT_LOG_URL,
590 | "checkpointLogHash": CHECKPOINT_LOG_HASH,
591 | "signature": [ SIGNATURES ]
592 | }
593 |
594 |
595 |
596 | A checkpoint event declares a CHECKPOINT_LOG_URL
597 | (e.g. https://example.org/ledger-agents/example/checkpoints/132) and a
598 | CHECKPOINT_LOG_HASH
599 | (e.g. urn:sha256:7fa3b9eaa8d92d2b87abf83d88a92ff23).
600 | All notaries typically download the checkpoint log and
601 | check it before providing signatures noting that the checkpoint log is valid.
602 | There is a detailed
603 | example of a checkpoint event
604 | in the appendix.
605 |
606 |
607 |
608 | How checkpoints are generated are a current topic of debate. The configuration
609 | event doesn't specify how often checkpoints can/should happen. It is also
610 | debatable that a checkpoint should be included in a consensus event and
611 | shouldn't be a separate event.
612 |
613 |
614 |
615 |
616 |
617 |
618 |
619 | Ledger Agent HTTP API
620 |
621 |
622 | The previous section defined the data model and messages that can be used
623 | to create and operate a ledger. This section provides the Ledger Agent
624 | HTTP API endpoints that may be used in conjunction with the messages in the
625 | previous section to create and operate a ledger.
626 |
627 |
628 |
629 | Note that the API proposed here only has one implementation and, while designed
630 | to be flexible, does not have enough deployment experience to be used in
631 | production systems that require strong interoperability guarantees. This is
632 | a work in progress.
633 |
634 |
635 |
636 | The `ledgerAgentStatusService` may not be necessary. Instead some text
637 | could be added indicating that the `id` of the Ledger Agent can be
638 | retrieved to get its status information.
639 |
640 |
641 |
642 |
643 | | Service |
644 | Example URL |
645 | Description |
646 |
647 |
648 |
649 | | ledgerAgentCreateService |
650 | POST /ledger-agents |
651 | Create a ledger agent. |
652 |
653 |
654 | | ledgerAgentListService |
655 | GET /ledger-agents |
656 | Get all ledger agents. |
657 |
658 |
659 | | ledgerAgentStatusService |
660 | GET /ledger-agents/{agent} |
661 | Get the current status of the ledger agent. |
662 |
663 |
664 | | ledgerEventService |
665 | POST /ledger-agents/{agent}/events |
666 | Request the addition of an event to ledger. |
667 |
668 |
669 | | ledgerBlockService |
670 | GET /ledger-agents/{agent}/blocks |
671 | Get a specific block from the ledger. |
672 |
673 |
674 | | ledgerQueryService |
675 | GET /ledger-agents/{agent}/query |
676 | Query the current state of the ledger. |
677 |
678 |
679 |
680 |
681 |
682 | Discovering Service Endpoints
683 |
684 |
685 | A website may provide service endpoint discover by embedding JSON-LD in their
686 | top-most HTML web page (e.g. at https://example.com/):
687 |
688 |
689 |
690 | <!DOCTYPE html>
691 | <html lang="en">
692 | <head>
693 | <meta charset="utf-8">
694 | <title>Example Website</title>
695 | <link rel="stylesheet" href="style.css">
696 | <script src="script.js"></script>
697 | <script type="application/ld+json">
698 | {
699 | "@context": "https://w3id.org/discovery/v1",
700 | "id": "https://example.com/",
701 | "name": "Example Website",
702 | "ledgerAgentCreateService": "https://example.com/ledger-agents",
703 | "ledgerAgentListService": "https://example.com/ledger-agents"
704 | }
705 | </script>
706 | </head>
707 | <body>
708 | <!-- page content -->
709 | </body>
710 | </html>
711 |
712 |
713 |
714 | Service descriptions may also be requested via content negotiation.
715 | In the following example a JSON-compatible service description is provided
716 | (e.g. curl -H "Accept: application/json" https://example.com/):
717 |
718 |
719 |
720 | {
721 | "@context": "https://w3id.org/discovery/v1",
722 | "id": "https://example.com/",
723 | "name": "Example Website",
724 | "ledgerAgentCreateService": "https://example.com/ledger-agents",
725 | "ledgerAgentListService": "https://example.com/ledger-agents"
726 | }
727 |
728 |
729 |
730 |
731 |
732 | Agent Create Service
733 |
734 |
735 | A ledger is created by performing an HTTP POST of a
736 | LedgerConfigurationBlock
737 | to the ledgerAgentCreateService. The following HTTP status codes
738 | are defined for this service:
739 |
740 |
741 |
742 |
743 | | HTTP Status |
744 | Description |
745 |
746 |
747 |
748 | | 201 |
749 |
750 | Ledger creation was successful. The HTTP Location header will
751 | contain the URL for the newly created ledger.
752 | |
753 |
754 |
755 | | 400 |
756 | Ledger creation failed. |
757 |
758 |
759 | | 409 |
760 | A duplicate ledger exists. |
761 |
762 |
763 |
764 |
765 |
766 | An example exchange of a ledger creation is shown below:
767 |
768 |
769 |
770 | POST /ledger-agents HTTP/1.1
771 | Host: example.com
772 | Content-Type: application/ld+json
773 | Content-Length: 1062
774 | Accept: application/ld+json, application/json, text/plain, */*
775 | Accept-Encoding: gzip, deflate
776 |
777 | {
778 | "@context": "https://w3id.org/web-ledger/v1",
779 | "id": "did:1628bf39-c8f9-453f-93d7-0fbdebb3dfef/blocks/1",
780 | "type": "LedgerConfigurationBlock",
781 | "ledgerConfig": {
782 | "id": "did:1628bf39-c8f9-453f-93d7-0fbdebb3dfef",
783 | "type": "LedgerConfiguration",
784 | "name": "example",
785 | "description": "An example ledger.",
786 | "storageMechanism": "SequentialList",
787 | "consensusAlgorithm": {
788 | "type": "ProofOfSignature2016",
789 | "approvedSigner": [
790 | "http://blue.example.com/keys/234",
791 | "http://red.example.com/keys/987",
792 | ],
793 | "minimumSignaturesRequired":1
794 | }
795 | },
796 | "previousBlock": {
797 | "hash": "urn:sha256:0000000000000000000000000000000000000000000000000000000000000000"
798 | },
799 | "signature": {
800 | "type": "RsaSignature2016",
801 | "created": "2016-10-14T18:35:33Z",
802 | "creator": "http://blue.example.com/keys/234",
803 | "signatureValue": "HvfvRQ57EO...J0Q=="
804 | }
805 | }
806 |
807 |
808 |
809 | If the creation of the ledger was successful, an HTTP 201 status code is
810 | expected in return:
811 |
812 |
813 |
814 | HTTP/1.1 201 Created
815 | Location: http://ledger.example.com/ledger-agents/example
816 | Cache-Control: no-cache, no-store, must-revalidate
817 | Pragma: no-cache
818 | Expires: 0
819 | Date: Fri, 14 Oct 2016 18:35:33 GMT
820 | Connection: keep-alive
821 | Transfer-Encoding: chunked
822 |
823 |
824 |
825 |
826 |
827 | Agent List Service
828 |
829 |
830 | One can get a list of active ledgers on a server by performing an HTTP GET on
831 | the ledgerListService. The following HTTP status codes
832 | are defined for this service:
833 |
834 |
835 |
836 |
837 | | HTTP Status |
838 | Description |
839 |
840 |
841 |
842 | | 200 |
843 |
844 | The list of ledgers was found and will be returned in the body of the response.
845 | |
846 |
847 |
848 | | 404 |
849 |
850 | The list of ledgers was not found at the given URL.
851 | |
852 |
853 |
854 |
855 |
856 |
857 | An example exchange of getting a list of ledgers on an HTTP server is shown
858 | below:
859 |
860 |
861 |
862 | GET /ledger-agents HTTP/1.1
863 | Host: example.com
864 | Connection: keep-alive
865 | Accept: application/ld+json, application/json, text/plain, */*
866 | Accept-Encoding: gzip, deflate, sdch
867 | Accept-Language: en-US,en;q=0.8
868 |
869 |
870 |
871 | If retrieving the list of ledgers is successful, a HTTP 200 response is
872 | expected:
873 |
874 |
875 |
876 | HTTP/1.1 200 OK
877 | Cache-Control: no-cache, no-store, must-revalidate
878 | Pragma: no-cache
879 | Expires: 0
880 | Access-Control-Allow-Origin: *
881 | Vary: Accept, Accept-Encoding
882 | Content-Type: application/ld+json; charset=utf-8
883 | Etag: W/"91d-mHiDWL0kix4rxP7JCtfVCA"
884 | Content-Encoding: gzip
885 | Date: Fri, 14 Oct 2016 18:46:04 GMT
886 | Connection: keep-alive
887 | Transfer-Encoding: chunked
888 |
889 | {
890 | "ledgerAgent": [
891 | {
892 | "id": "https://example.com/ledger-agents/example",
893 | "name": "example",
894 | "ledgerAgentStatusService": "https://example.com/ledger-agents/example",
895 | "ledgerQueryService": "https://example.com/ledger-agents/example/query",
896 | "ledgerEventService": "https://example.com/ledger-agents/example/events",
897 | "ledgerBlockService": "https://example.com/ledger-agents/example/blocks",
898 | "ledgerConfig": {
899 | "id": "did:de7adbe7-79f2-425a-9dfb-76a234782f30",
900 | "type": "LedgerConfiguration",
901 | "name": "example",
902 | "description": "An example ledger.",
903 | "storageMechanism": "SequentialList",
904 | "consensusAlgorithm": {
905 | "type": "ProofOfSignature2016",
906 | "approvedSigner": [
907 | "https://blue.example.com/keys/234",
908 | "https://red.example.com/keys/789"
909 | ],
910 | "minimumSignaturesRequired": 1
911 | }
912 | },
913 | "latestBlock": {
914 | "id": "did:de7adbe7-79f2-425a-9dfb-76a234782f30/blocks/1",
915 | "hash": "urn:sha256:7eb0603c9a3982284c7db09b1eb40bc85a1177bdc594b027fba0e746b79db15b"
916 | },
917 | "nextBlock": {
918 | "id": "did:de7adbe7-79f2-425a-9dfb-76a234782f30/blocks/2"
919 | }
920 | },
921 | {
922 | ... NEXT_LEDGER_IN_LIST ...
923 | }
924 | ]
925 | }
926 |
927 |
928 |
929 |
930 |
931 | Agent Status Service
932 |
933 |
934 | The metadata related to a ledger agent may be fetched by performing an HTTP GET
935 | on the ledgerAgentStatusService. The following HTTP status codes
936 | are defined for this service:
937 |
938 |
939 |
940 |
941 | | HTTP Status |
942 | Description |
943 |
944 |
945 |
946 | | 200 |
947 |
948 | The ledger agent status was found and will be returned in the body of the response.
949 | |
950 |
951 |
952 | | 404 |
953 |
954 | The ledger agent status was not found at the given URL.
955 | |
956 |
957 |
958 |
959 |
960 |
961 | An example exchange of fetching metadata for a ledger is shown below:
962 |
963 |
964 |
965 |
966 | GET /ledger-agents/example HTTP/1.1
967 | Host: example.com
968 | Connection: keep-alive
969 | Accept: application/ld+json, application/json, text/plain, */*
970 | Accept-Encoding: gzip, deflate, sdch
971 | Accept-Language: en-US,en;q=0.8
972 |
973 |
974 |
975 | If retrieving the ledger metadata is successful, an HTTP 200 response is
976 | expected:
977 |
978 |
979 |
980 | HTTP/1.1 200 OK
981 | Cache-Control: no-cache, no-store, must-revalidate
982 | Pragma: no-cache
983 | Expires: 0
984 | Access-Control-Allow-Origin: *
985 | Vary: Accept, Accept-Encoding
986 | Content-Type: application/ld+json; charset=utf-8
987 | Etag: W/"91d-mHiDWL0kix4rxP7JCtfVCA"
988 | Content-Encoding: gzip
989 | Date: Fri, 14 Oct 2016 18:46:04 GMT
990 | Connection: keep-alive
991 | Transfer-Encoding: chunked
992 |
993 | {
994 | "id": "https://example.com/ledger-agents/example",
995 | "name": "example",
996 | "ledgerAgentStatusService": "https://example.com/ledger-agents/example",
997 | "ledgerQueryService": "https://example.com/ledger-agents/example/query",
998 | "ledgerEventService": "https://example.com/ledger-agents/example/events",
999 | "ledgerBlockService": "https://example.com/ledger-agents/example/blocks",
1000 | "ledgerConfig": {
1001 | "id": "did:de7adbe7-79f2-425a-9dfb-76a234782f30",
1002 | "type": "LedgerConfiguration",
1003 | "name": "example",
1004 | "description": "An example ledger.",
1005 | "storageMechanism": "SequentialList",
1006 | "consensusAlgorithm": {
1007 | "type": "ProofOfSignature2016",
1008 | "approvedSigner": [
1009 | "https://blue.example.com/keys/234",
1010 | "https://red.example.com/keys/789"
1011 | ],
1012 | "minimumSignaturesRequired":1
1013 | }
1014 | },
1015 | "latestBlock": {
1016 | "id": "did:de7adbe7-79f2-425a-9dfb-76a234782f30/blocks/1",
1017 | "hash": "urn:sha256:7eb0603c9a3982284c7db09b1eb40bc85a1177bdc594b027fba0e746b79db15b"
1018 | },
1019 | "nextBlock": {
1020 | "id": "did:de7adbe7-79f2-425a-9dfb-76a234782f30/blocks/2"
1021 | }
1022 | }
1023 |
1024 |
1025 |
1026 |
1027 |
1028 | Ledger Append Service
1029 |
1030 |
1031 | Appending to a ledger can be achieved by performing an HTTP POST of a
1032 | LedgerStorageBlock
1033 | to the ledgerAppendService. The following HTTP status codes
1034 | are defined for this service:
1035 |
1036 |
1037 |
1038 |
1039 | | HTTP Status |
1040 | Description |
1041 |
1042 |
1043 |
1044 | | 201 |
1045 |
1046 | The ledger block was sucessfully appended.
1047 | |
1048 |
1049 |
1050 | | 400 |
1051 |
1052 | The ledger block failed to be appended.
1053 | |
1054 |
1055 |
1056 | | 409 |
1057 |
1058 | The ledger block with the given identifier already exists.
1059 | |
1060 |
1061 |
1062 |
1063 |
1064 |
1065 | An example of an event being appended to a ledger is shown below:
1066 |
1067 |
1068 |
1069 | POST /ledger-agents/example/events HTTP/1.1
1070 | Host: example.com
1071 | Connection: keep-alive
1072 | Content-Length: 1054
1073 | Content-Type: application/json;charset=UTF-8
1074 | Accept: application/ld+json, application/json, text/plain, */*
1075 | Accept-Encoding: gzip, deflate
1076 | Accept-Language: en-US,en;q=0.8
1077 |
1078 | {
1079 | "@context": ["https://w3id.org/web-ledger/v1", "https://w3id.org/fema/v1"],
1080 | "type": "LedgerStorageEvent",
1081 | "setObject": [{
1082 | "id": "https://fema.gov/credentials/9754457",
1083 | "type": ["Credential", "EmergencyResponderCredential"],
1084 | "claim": {
1085 | "id": "did:bc380e48-a6d9-4602-ab20-1beb403d4bcc",
1086 | "emsLicense": {
1087 | "id": "ems:FF-12-01655",
1088 | "status": "valid"
1089 | }
1090 | }
1091 | }],
1092 | "signature": {
1093 | "type": "RsaSignature2016",
1094 | "created": "2016-10-14T19:47:15Z",
1095 | "creator": "https://example.com/keys/fema-key-1",
1096 | "signatureValue": "JoS27wqaTX...s0mpBFMgXIMw=="
1097 | }
1098 | }
1099 |
1100 |
1101 |
1102 | If the storage attempt is successful, a HTTP 200 response is expected:
1103 |
1104 |
1105 |
1106 | HTTP/1.1 201 Created
1107 | Location: https://example.com/ledger-agents/example/events?id=d1328828-3d44-4e14-9c3a-263af54ed032
1108 | Cache-Control: no-cache, no-store, must-revalidate
1109 | Pragma: no-cache
1110 | Expires: 0
1111 | Date: Fri, 14 Oct 2016 19:47:16 GMT
1112 | Connection: keep-alive
1113 | Transfer-Encoding: chunked
1114 |
1115 |
1116 |
1117 |
1118 |
1119 | Ledger Block Service
1120 |
1121 |
1122 | A ledger read for an block is achieved by performing an HTTP GET on
1123 | a ledger block identifier. The list of ledger blocks is available by performing
1124 | an HTTP GET on the ledgerBlockService. The following HTTP status
1125 | codes are defined for this service:
1126 |
1127 |
1128 |
1129 |
1130 | | HTTP Status |
1131 | Description |
1132 |
1133 |
1134 |
1135 | | 200 |
1136 |
1137 | Retrieval of the ledger block was successful.
1138 | |
1139 |
1140 |
1141 | | 404 |
1142 |
1143 | The ledger block was not found at the given URL.
1144 | |
1145 |
1146 |
1147 |
1148 |
1149 |
1150 | An example retrieval of a ledger block is shown below:
1151 |
1152 |
1153 |
1154 | GET /ledger-agents/example/blocks?id=did:de7adbe7-79f2-425a-9dfb-76a234782f30/blocks/2 HTTP/1.1
1155 | Host: example.com
1156 | Connection: keep-alive
1157 | Accept: application/ld+json, application/json, text/plain, */*
1158 | Accept-Encoding: gzip, deflate, sdch
1159 | Accept-Language: en-US,en;q=0.8
1160 |
1161 |
1162 |
1163 | If the ledger block retrieval is successful, a HTTP 200 response is expected:
1164 |
1165 |
1166 |
1167 | HTTP/1.1 200 OK
1168 | Cache-Control: no-cache, no-store, must-revalidate
1169 | Pragma: no-cache
1170 | Expires: 0
1171 | Access-Control-Allow-Origin: *
1172 | Vary: Accept, Accept-Encoding
1173 | Content-Type: application/ld+json; charset=utf-8
1174 | Etag: W/"41e-PJKXv/OxofX29WykKb3PZg"
1175 | Content-Encoding: gzip
1176 | Date: Fri, 14 Oct 2016 20:20:44 GMT
1177 | Connection: keep-alive
1178 | Transfer-Encoding: chunked
1179 |
1180 | {
1181 | "@context": ["https://w3id.org/web-ledger/v1", "https://w3id.org/fema/v1"],
1182 | "id": "did:de7adbe7-79f2-425a-9dfb-76a234782f30/blocks/2",
1183 | "type": "LedgerStorageBlock",
1184 | "setObject": [{
1185 | "id": "https://fema.gov/credentials/9754457",
1186 | "type": ["Credential", "EmergencyResponderCredential"],
1187 | "claim": {
1188 | "id": "did:bc380e48-a6d9-4602-ab20-1beb403d4bcc",
1189 | "emsLicense": {
1190 | "id": "ems:FF-12-01655",
1191 | "status": "valid"
1192 | }
1193 | }
1194 | }],
1195 | "previousBlock": {
1196 | "id": "did:de7adbe7-79f2-425a-9dfb-76a234782f30/blocks/1",
1197 | "hash": "urn:sha256:7eb0603c9a3982284c7db09b1eb40bc85a1177bdc594b027fba0e746b79db15b"
1198 | },
1199 | "signature": {
1200 | "type": "RsaSignature2016",
1201 | "created": "2016-10-14T19:47:15Z",
1202 | "creator": "http://example.com/keys/789",
1203 | "signatureValue": "JoS27wqa...BFMgXIMw=="
1204 | }
1205 | }
1206 |
1207 |
1208 |
1209 |
1210 |
1211 |
1212 | Ledger Query Service
1213 |
1214 |
1215 | The current state machine of a ledger may be queried by performing an
1216 | HTTP GET on the ledgerQueryService. The following HTTP status
1217 | codes are defined for this service:
1218 |
1219 |
1220 |
1221 |
1222 | | HTTP Status |
1223 | Description |
1224 |
1225 |
1226 |
1227 | | 200 |
1228 |
1229 | Retrieval of the latest state machine object was successful.
1230 | |
1231 |
1232 |
1233 | | 400 |
1234 |
1235 | The query was malformed.
1236 | |
1237 |
1238 |
1239 | | 404 |
1240 |
1241 | The given state machine object was not found.
1242 | |
1243 |
1244 |
1245 |
1246 |
1247 |
1248 | An example query of a state machine in a ledger is shown below:
1249 |
1250 |
1251 |
1252 | GET /ledger-agents/example/query?id=http://www.coupon-clearing.org/coupons/486211708 HTTP/1.1
1253 | Host: example.com
1254 | Connection: keep-alive
1255 | Accept: application/ld+json, application/json, text/plain, */*
1256 | Accept-Encoding: gzip, deflate, sdch
1257 | Accept-Language: en-US,en;q=0.8
1258 |
1259 |
1260 |
1261 | If the query is successful, a HTTP 200 response is expected:
1262 |
1263 |
1264 |
1265 | {
1266 | "id": "http://www.coupon-clearing.org/coupons/486211708",
1267 | "type": ["Credential", "DiscountCoupon"],
1268 | "claim": {
1269 | "id": "upc:956578900933",
1270 | "discount": "$3",
1271 | "description": "Discount when you buy 5 pounds of JuicyGreen Apples",
1272 | "status": "redeemed"
1273 | }
1274 | }
1275 |
1276 |
1277 |
1278 |
1279 |
1280 |
1281 |
1282 | Industry-specific Examples
1283 |
1284 |
1285 | Configuring the Ledger
1286 |
1287 |
1288 | {
1289 | "@context": "https://w3id.org/web-ledger/v1",
1290 | "id": "did:f6ea280f-8011-4502-a29f-464954de3427/blocks/1",
1291 | "type": "LedgerConfigurationBlock",
1292 | "ledgerConfig": {
1293 | "id": "did:f6ea280f-8011-4502-a29f-464954de3427",
1294 | "type": "LedgerConfiguration",
1295 | "name": "example",
1296 | "description": "example ledger",
1297 | "storageMechanism": "SequentialList",
1298 | "consensusAlgorithm": {
1299 | "type": "ProofOfSignature2016",
1300 | "approvedSigner": [
1301 | "https://blue.example.com/keys/j37f8",
1302 | "https://red.example.com/keys/83hfk",
1303 | ],
1304 | "minimumSignaturesRequired":1
1305 | }
1306 | },
1307 | "previousBlock": {
1308 | "hash": "urn:sha256:0000000000000000000000000000000000000000000000000000000000000000"
1309 | },
1310 | "signature": {
1311 | "type": "RsaSignature2016",
1312 | "created": "2016-10-05T11:47:26Z",
1313 | "creator": "http://blue.example.com/keys/j37f8",
1314 | "signatureValue": "RG+t2EbnMKr4zIwgncLHTb/JvAZ/EIXmTXrrad7DBdlchKPPC9j91N793eHY5UYx4zx7PTDnU2HlW9zqQD1EMBwI7TtqE7BfvxOFodjKJ/Aw16vpAmw2h2Jo9NBu4BvFWsLPCiMLHuW7Vxo7XDkGVfaZUqk/X2q/xpRmqJ1tOlNgivUH8bIm/TUAG3g90DMN9s5zImVyB4B20zMJk8K50BbpHYKUVNWCaHnv9F4VvUUa+AdNeNlC8W1F5j2WChyXzd+51bervxQErZUDFyocW/xEYPvJXPSGnL0ARBDggKQDe1M3bg8w7GnMGrJBieNZAuK2mxOtF2rOPDU3oMk3ZQ=="
1315 | }
1316 | }
1317 |
1318 |
1319 |
1320 | {
1321 | "@context": "https://w3id.org/web-ledger/v1",
1322 | "id": "https://example.us.gov/ledger-agents/emergency-response/1",
1323 | "type": "LedgerConfigurationBlock",
1324 | "storageMechanism": "SequentialList",
1325 | "consensusAlgorithm": {
1326 | "type": "ProofOfSignature2016",
1327 | "approvedSigner": [
1328 | "https://fema.example.us.gov/i/ofp",
1329 | "https://tsa.example.us.gov/i/vclaims",
1330 | "https://dhs.example.us.gov/i/credentialing",
1331 | ],
1332 | "minimumSignaturesRequired": 1
1333 | },
1334 | "nextBlock": "https://example.us.gov/ledger-agents/emergency-response/2",
1335 | "signature": {
1336 | "type": "LinkedDataSignature2016",
1337 | "created": "2016-09-19T17:19:52Z",
1338 | "creator": "https://fema.example.gov/i/credentialing/keys/7f6",
1339 | "signatureValue": "pjeyuFq9idhwHGfGFzv...9fjsk=="
1340 | }
1341 | }
1342 |
1343 |
1344 |
1345 | {
1346 | "@context": [
1347 | "https://w3id.org/web-ledger/v1",
1348 | "https://w3id.org/cryptocurrencies/v1"
1349 | ],
1350 | "id": "bytecoin:block:23fa73bb201c738d",
1351 | "type": "LedgerConfigurationBlock",
1352 | "storageMechanism": "MerkleTree",
1353 | "consensusAlgorithm": {
1354 | "type": "ProofOfWork2016",
1355 | "proofOfWorkAlgorithm": "Bitcoin",
1356 | "targetDifficulty": "199312067531.243"
1357 | },
1358 | "signature": {
1359 | "type": "LinkedDataSignature2016",
1360 | "created": "2017-01-24T02:10:21Z",
1361 | "creator": "bytecoin:keys:23f3b2c8183bdd52aff689",
1362 | "signatureValue": "90D4cFqT/yKPiwd/GFzv...NJGL=="
1363 | }
1364 | }
1365 |
1366 |
1367 |
1368 | {
1369 | "@context": [
1370 | "https://w3id.org/web-ledger/v1",
1371 | "https://w3id.org/cryptocurrencies/v1"
1372 | ],
1373 | "id": "https://example-consortium.com/private-ledgers/loans/real-estate/1",
1374 | "type": "LedgerConfigurationBlock",
1375 | "storageMechanism": "SequentialList",
1376 | "consensusAlgorithm": {
1377 | "type": "ProofOfBallot2015",
1378 | "minimumQuorumPercentage": "0.51",
1379 | "minimumVotePercentage": "0.67",
1380 | "approvedSigner": [
1381 | "https://regulator-a.gov/i/bank-oversight",
1382 | "https://regulator-b.gov/i/consumer-protection",
1383 | "https://bank-x.com/i/housing",
1384 | "https://bank-y.com/i/corporate-loans",
1385 | "https://bank-z.com/i/swaps",
1386 | ]
1387 | },
1388 | "signature": [{
1389 | "type": "LinkedDataSignature2016",
1390 | "created": "2018-04-16T19:34:18Z",
1391 | "creator": "https://regulator-b.gov/i/consumer-protection/keys/2f73",
1392 | "signatureValue": "Piw90D4cFqT/yKd/JGLv...NGFz=="
1393 | }, ... // there will be at least 3 more signatures here
1394 | ]
1395 | }
1396 |
1397 |
1398 |
1399 | The use of nextBlock is unlikely here, it is more
1400 | likely to be prevBlock and potentially include
1401 | a hash of that event depending on configuration.
1402 |
1403 |
1404 |
1405 |
1406 |
1407 | Storing Data in the Ledger
1408 |
1409 |
1410 |
1411 |
1412 |
1413 |
1414 | {
1415 | "@context": ["https://w3id.org/web-ledger/v1", "https://w3id.org/dhs/v1"],
1416 | "id": "did:f6ea280f-8011-4502-a29f-464954de3427/blocks/2",
1417 | "type": "LedgerStorageBlock",
1418 | "setObject": [{
1419 | "id": "https://hhs.gov/vaccinations/6080026",
1420 | "type": ["Credential", "VaccinationCredential"],
1421 | "claim": {
1422 | "id": "did:e277ce82-bf9d-413a-a6fe-fde877fd19b1",
1423 | "vaccination": {
1424 | "type": "IPV",
1425 | "vaccinationDate": "2004-07-17",
1426 | "vaccinationProvider": "Alameda County Hospital, California, USA"
1427 | }
1428 | }
1429 | }],
1430 | "previousBlock": {
1431 | "id": "did:f6ea280f-8011-4502-a29f-464954de3427/blocks/1",
1432 | "hash": "urn:sha256:f04524659baa027ea49e7d0635bc6b1869d3e7d811f6bfefeb3aae1adcae0362"
1433 | },
1434 | "signature": {
1435 | "type": "RsaSignature2016",
1436 | "created": "2016-10-12T18:37:27Z",
1437 | "creator": "http://ledger.example.com/keys/fema-key-1",
1438 | "signatureValue": "ITv0b9tTIjgBMgu4jUOsuU9Y2t9rsq+rKrbJHfcKWmDQZE1X6VpqKowv3l27WN0w5NyECIkJx6oy94nlM375ivmhQf6iYd6R7IizVBiRiLl3HeNXdaxBpyYMn6OiP8MYVdJt2g5vj+xhP9AadXnRL0TYmE6qH1LtOw42SQtfseQDb8xF1Bsjie7KmKK/G+B1yoKqg1L34NLSAnHpnqRGAen9OEMi0hwBrVD8HIRFkdCehh4T07HRrZe2mwhfY0gOA54j02qWZxidvYUYAV8vax4AhFyk0Vsaibo9yt85uU8Tc8a4e5hjS7nCAya8FMzDd0xEOp1q9MeC5vgJHKz29g=="
1439 | }
1440 | }
1441 |
1442 |
1443 |
1444 | {
1445 | "@context": [
1446 | "https://w3id.org/web-ledger/v1",
1447 | "https://w3id.org/housing/v1",
1448 | ],
1449 | "id": "https://vhda.va.us.gov/ledger-agents/webville/houses/2",
1450 | "type": "LedgerStorageBlock",
1451 | "previousBlock": "https://example-consortium.com/private-ledgers/loans/real-estate/1",
1452 | "setObject": [{
1453 | "id": "https://vhda.va.us.gov/properties/3829344",
1454 | "propertyAddress": {
1455 | "street": "263 Main Street",
1456 | "locality": "Webville",
1457 | "region": "VA",
1458 | "postalCode": "24736-3726",
1459 | "country": "US"
1460 | },
1461 | "owner": {
1462 | "name": "Jane Smith",
1463 | "postalAddress": { ... }
1464 | }],
1465 | "signature": {
1466 | "type": "LinkedDataSignature2016",
1467 | "created": "2016-02-22T02:10:21Z",
1468 | "creator": "https://webville.va.us.gov/i/planning-department/keys/1",
1469 | "signatureValue": "cNJGLFqT/d/90D4GFzv...yKPiw=="
1470 | }
1471 | }
1472 |
1473 |
1474 |
1475 | {
1476 | "@context": [
1477 | "https://w3id.org/web-ledger/v1",
1478 | "https://w3id.org/dhs/credentials/v1",
1479 | ],
1480 | "id": "https://example.us.gov/ledger-agents/emergency-response/2",
1481 | "type": "LedgerStorageBlock",
1482 | "previousBlock": "https://example.us.gov/ledger-agents/emergency-response/1",
1483 | "setObject": [{
1484 | "id": "https://example.us.gov/credentials/234234542",
1485 | "type": ["Credential", "EmergencyResponseCredential"]
1486 | "claim": {
1487 | "id": "did:3f32-23425-53-241442",
1488 | "emsLicense": {
1489 | "id": "FF-37-48573",
1490 | "status": "valid"
1491 | },
1492 | }],
1493 | "signature": {
1494 | "type": "LinkedDataSignature2016",
1495 | "created": "2016-09-19T17:19:52Z",
1496 | "creator": "https://fema.example.gov/i/credentialing/keys/7f6",
1497 | "signatureValue": "pjeyuFq9idhwHGfGFzv...9fjsk=="
1498 | }
1499 | }
1500 |
1501 |
1502 |
1503 | {
1504 | "@context": [
1505 | "https://w3id.org/web-ledger/v1",
1506 | "https://w3id.org/cryptocurrencies/v1"
1507 | ],
1508 | "id": "bytecoin:block:83ba663df28372718",
1509 | "type": "LedgerStorageBlock",
1510 | "previousBlock": "bytecoin:block:271863df2883ba637",
1511 | "addsObject": [{
1512 | "transaction": [{
1513 | "https://w3id.org/bytecoin/v1",
1514 | "source": "bytecoin:2892316f63778",
1515 | "destination": "bytecoin:983bba526fd6",
1516 | "input": [...], // the inputs to the transaction
1517 | "output": [...], // the outputs from the transaction
1518 | "transfer": {
1519 | "amount": "0.3928621",
1520 | "currency": "bytecoin:currency:bco"
1521 | }
1522 | }], ... // there could be hundreds to thousands more of these
1523 | }]
1524 | "signature": {
1525 | "type": "LinkedDataSignature2016",
1526 | "created": "2017-01-24T02:11:16Z",
1527 | "creator": "bytecoin:key:23fa73bb201c738d",
1528 | "signatureValue": "90D4cFqT/yKPiwd/GFzv...NJGL=="
1529 | }
1530 | }
1531 |
1532 |
1533 |
1534 | {
1535 | "@context": [
1536 | "https://w3id.org/web-ledger/v1",
1537 | "https://w3id.org/real-estate/v1"
1538 | ],
1539 | "id": "https://example-consortium.com/private-ledgers/loans/real-estate/2",
1540 | "type": "LedgerStorageBlock",
1541 | "previousBlock": "https://example-consortium.com/private-ledgers/loans/real-estate/1",
1542 | "addsObject": [{
1543 | "id": "https://example-consortium.com/private-ledgers/loans/real-estate/transactions/238947234",
1544 | "transaction": {
1545 | "source": "lei:HB7FFAZIO0MZ8PP8OE26", // compliant to ISO 17442 standard
1546 | "destination": "lei:PP8OEHB7FFAZIO0MZ826",
1547 | "transfer": {
1548 | "loanId": "lei:FAZIO0PP8OEHB7FMZ826"
1549 | }
1550 | }
1551 | }],
1552 | "signature": [{
1553 | "type": "LinkedDataSignature2016",
1554 | "created": "2018-04-16T19:34:18Z",
1555 | "creator": "https://regulator-b.gov/i/consumer-protection/keys/2f73",
1556 | "signatureValue": "Piw90D4cFqT/yKd/JGLv...NGFz=="
1557 | }, ... // there will be at least 3 more signatures here
1558 | ]
1559 | }
1560 |
1561 |
1562 |
1563 |
1564 |
1565 | Recording Consensus
1566 |
1567 |
1568 | {
1569 | "@context": "https://w3id.org/web-ledger/v1",
1570 | "id": "did:f6ea280f-8011-4502-a29f-464954de3427/blocks/100",
1571 | "type": "ConsensusBlock",
1572 | "previousBlock": {
1573 | "id": "did:f6ea280f-8011-4502-a29f-464954de3427/blocks/99",
1574 | "hash": "urn:sha256:0877a494ce1705117f917a3af3fc48190b1fdbca04fdba8e995fd6c15fb2fe71"
1575 | },
1576 | "signature": [{
1577 | "type": "RsaSignature2016",
1578 | "created": "2016-10-12T19:54:12Z",
1579 | "creator": "https://notary1.example.org/keys/124",
1580 | "signatureValue": "skeJ4...lBUiI858="
1581 | }, {
1582 | "type": "RsaSignature2016",
1583 | "created": "2016-10-12T19:54:32Z",
1584 | "creator": "https://notary2.example.org/keys/f31",
1585 | "signatureValue": "iamOjOGncO...gRXfsG0="
1586 | }, {
1587 | "type": "RsaSignature2016",
1588 | "created": "2016-10-12T19:54:56Z",
1589 | "creator": "https://notary3.example.org/keys/35",
1590 | "signatureValue": "cPehH...iI858="
1591 | }, {
1592 | "type": "RsaSignature2016",
1593 | "created": "2016-10-12T19:54:23Z",
1594 | "creator": "https://notary4.example.org/keys/ugref2",
1595 | "signatureValue": "hMaD22...ONwzsgo="
1596 | }]
1597 | }
1598 |
1599 |
1600 |
1601 |
1602 | Checkpointing Ledger State
1603 |
1604 |
1605 | A checkpoint log is an entry in the ledger that
1606 |
1607 |
1608 |
1609 | Don't really know if checkpoints are /that/ useful without
1610 | prevId entries. Don't really know if checkpoints
1611 | are that useful at all? Seems to be the only use is a link
1612 | to a compressed/checksummed file?
1613 |
1614 |
1615 |
1616 | {
1617 | "@context": "https://w3id.org/web-ledger/v1",
1618 | "id": "https://example.org/ledger-agents/example/6372463",
1619 | "type": "LedgerCheckpointBlock",
1620 | "checkpointLog": "https://example.org/ledger-agents/example/checkpoints/132",
1621 | "checkpointLogHash": "urn:sha256:7fa3b9eaa8d92d2b87abf83d88a92ff23",
1622 | "signature": [{
1623 | "type": "LinkedDataSignature2016",
1624 | "created": "2018-04-16T19:34:18Z",
1625 | "creator": "https://example.org/i/master/keys/32",
1626 | "signatureValue": "Piw90D4cFqT/yKd/JGLv...NGFz=="
1627 | }, ... // there may be multiple counter-signatures here
1628 | ]
1629 | }
1630 |
1631 |
1632 |
1633 |
1634 | Linking to Other Ledgers
1635 |
1636 |
1637 |
1638 |
1639 |
1640 | {
1641 | "@context": [
1642 | "https://w3id.org/web-ledger/v1",
1643 | "https://w3id.org/cryptocurrencies/v1"
1644 | ],
1645 | "id": "https://example.org/ledger-agents/example/5",
1646 | "type": "LedgerStorageBlock",
1647 | "previousBlock": "https://example.org/ledger-agents/example/4",
1648 | "addsObject": [{
1649 | "transaction": [{
1650 | "source": "https://example.org/accounts/jane/7",
1651 | "destination": "https://foo.com/accounts/bob/3",
1652 | "remoteLedger": "https://foo.com/ledger-agents/blah/3445",
1653 | "transfer": {
1654 | "amount": "23.45",
1655 | "currency": "USD"
1656 | }
1657 | }], ... // there could be hundreds to thousands more of these
1658 | }]
1659 | "signature": {
1660 | "type": "LinkedDataSignature2016",
1661 | "created": "2017-01-24T02:11:16Z",
1662 | "creator": "bytecoin:key:23fa73bb201c738d",
1663 | "signatureValue": "90D4cFqT/yKPiwd/GFzv...NJGL=="
1664 | }
1665 | }
1666 |
1667 |
1668 |
1669 |
1670 |
1671 |
1672 |
117 | Event Classes
118 |
119 |
121 | CheckpointEvent
122 |
123 | An event that is used to provide a snapshot in time that can be used to
124 | quickly bootstrap late-joining nodes in a system. Checkpoint events can also
125 | be used as known good points to start from instead of having to download the
126 | entire ledger history.
127 |
128 |
129 | - Status
130 | - unstable
131 | - Parent Class
132 | - owl:Thing
133 | - Expected properties
134 | - checkpointLog, checkpointLogHash, signature
135 |
136 |
137 | The example below describes a checkpoint event with a checkpoint log located
138 | at https://example.org/ledgers/example/checkpoints/132 whose
139 | contents hash to a SHA-256 value of
140 | 7fa3b9eaa8d92d2b87abf83d88a92ff23:
141 |
142 |
143 | {
144 | "@context": "https://w3id.org/flex/v1",
145 | "id": "https://example.org/ledgers/example/6372463",
146 | "type": "LedgerCheckpointEvent",
147 | "checkpointLog": "https://example.org/ledgers/example/checkpoints/132",
148 | "checkpointLogHash": "urn:sha256:7fa3b9eaa8d92d2b87abf83d88a92ff23",
149 | "signature": [{
150 | "type": "LinkedDataSignature2016",
151 | "created": "2018-04-16T19:34:18Z",
152 | "creator": "https://example.org/i/master/keys/32",
153 | "signatureValue": "Piw90D4cFqT/yKd/JGLv...NGFz=="
154 | }, ... // there may be multiple counter-signatures here
155 | ]
156 | }
157 |
158 |
159 |
160 |
162 | ConsensusEvent
163 |
164 | An event where the network of nodes curating a particular ledger come to an
165 | agreement on the correct state of the ledger. The mechanism used to come to
166 | agreement is configurable.
167 |
168 |
169 | - Status
170 | - unstable
171 | - Parent Class
172 | - owl:Thing
173 | - Expected properties
174 | - previousConsensusEvent, acknowledgedEvents, signature
175 |
176 |
177 | The example below describes a consensus event that includes a link to a
178 | previousConsensusEvent, a list of acknowledged events, and a set of signatures
179 | by multiple entities proving that the consensus ballot had a finalized
180 | outcome:
181 |
182 |
183 | {
184 | "@context": "https://w3id.org/flex/v1",
185 | "id": "https://example.org/ledgers/example/8239849843",
186 | "type": ["LedgerConsensusEvent", "ProofOfBallot2015"],
187 | "previousConsensusEvent": "https://example.org/ledgers/example/8239848234",
188 | "acknowledgedEvents": [
189 | "https://example.org/ledgers/example/8239849838",
190 | "https://example.org/ledgers/example/8239849839",
191 | "https://example.org/ledgers/example/8239849840",
192 | "https://example.org/ledgers/example/8239849841",
193 | "https://example.org/ledgers/example/8239849842",
194 | ],
195 | "signature": [{
196 | "type": "LinkedDataSignature2016",
197 | "created": "2018-04-16T19:34:18Z",
198 | "creator": "https://webville.va.us.gov/i/planning-department/keys/12",
199 | "signatureValue": "4cF/yKd/JPiw90DqTGLv...NGFz=="
200 | }, // other signatures on votes in favor follow...
201 | ]
202 | }
203 |
204 |
205 |
206 |
208 | ConfigurationEvent
209 |
210 | An event noting that the operational rules of the ledger have changed. This
211 | event is typically only active after the next ConsensusEvent has taken place.
212 |
213 |
214 | - Status
215 | - unstable
216 | - Parent Class
217 | - owl:Thing
218 | - Expected properties
219 | - storageMechanism, consensusAlgorithm, signature
220 |
221 |
222 | The example below describes a configuration event for a ledger. The
223 | configuration event states that the storage mechanism for the ledger is a
224 | sequential list and the consensus algorithm requires one valid signature:
225 |
226 |
227 | {
228 | "@context": "https://w3id.org/flex/v1",
229 | "id": "https://vhda.va.us.gov/ledgers/webville/houses/1",
230 | "type": "LedgerConfigurationEvent",
231 | "storageMechanism": "SequentialList",
232 | "consensusAlgorithm": {
233 | "type": "ProofOfSignature2016",
234 | "approvedSigner": "https://webville.va.us.gov/i/planning-department",
235 | "minimumSignaturesRequired": 1
236 | },
237 | "nextEvent": "https://vhda.va.us.gov/ledgers/webville/houses/2",
238 | "signature": {
239 | "type": "LinkedDataSignature2016",
240 | "created": "2016-02-21T02:10:21Z",
241 | "creator": "https://webville.va.us.gov/i/planning-department/keys/1",
242 | "signatureValue": "cNJGLFqT/d/90D4GFzv...yKPiw=="
243 | }
244 | }
245 |
246 |
247 |
248 |
250 | StorageEvent
251 |
252 | An event noting that a ledger value has changed. Changes to a ledger can be
253 | modifications to the state machine such as the addition of values, removal
254 | of values, or modification of values.
255 |
256 |
257 | - Status
258 | - unstable
259 | - Parent Class
260 | - owl:Thing
261 | - Expected properties
262 | - addsObject, removesObject, replacesObject, signature
263 |
264 |
265 | The example below describes a storage event containing a financial
266 | transaction and a link to the previous ledger event:
267 |
268 |
269 | {
270 | "@context": [
271 | "https://w3id.org/flex/v1",
272 | "https://w3id.org/cryptocurrencies/v1"
273 | ],
274 | "id": "https://example.org/ledgers/example/5",
275 | "type": "LedgerStorageEvent",
276 | "previousEvent": "https://example.org/ledgers/example/4",
277 | "addsObject": [{
278 | "transaction": [{
279 | "source": "https://example.org/accounts/jane/7",
280 | "destination": "https://foo.com/accounts/bob/3",
281 | "remoteLedger": "https://foo.com/ledgers/blah/3445",
282 | "transfer": {
283 | "amount": "23.45",
284 | "currency": "USD"
285 | }
286 | }], ... // there could be hundreds to thousands more of these
287 | }]
288 | "signature": {
289 | "type": "LinkedDataSignature2016",
290 | "created": "2017-01-24T02:11:16Z",
291 | "creator": "bytecoin:key:23fa73bb201c738d",
292 | "signatureValue": "90D4cFqT/yKPiwd/GFzv...NJGL=="
293 | }
294 | }
295 |
296 |
297 |
298 |
299 |
300 | Storage Classes
301 |
302 |
304 | MerklePatriciaTrie
305 |
306 | A storage mechanism that combines a
307 | Merkle Tree with a
308 | radix-sorted trie thus
309 | creating a quickly searchable hashtree. Merkle-Patricia Tries are
310 | fully deterministic meaning that re-creating the tree results in the same
311 | root hash and byte-perfect key-value bindings. This data structure
312 | provides O(log(n)) efficiency for inserts, lookups and deletes, and are
313 | simpler to implement and understand. The Ethereum blockchain uses
314 | Merkle-Patricia Tries for storage.
315 |
316 |
317 | - Status
318 | - unstable
319 | - Parent Class
320 | - owl:Thing
321 | - Used by
322 | - storageMechanism
323 |
324 |
325 | The example below describes a configuration event where the selected storage
326 | mechanism is a Merkle-Patricia trie:
327 |
328 |
329 | {
330 | "@context": [
331 | "https://w3id.org/flex/v1",
332 | "https://w3id.org/cryptocurrencies/v1"
333 | ],
334 | "id": "lux:entry:37823",
335 | "type": "LedgerConfigurationEvent",
336 | "storageMechanism": "MerklePatriciaTrie",
337 | "consensusAlgorithm": {
338 | "type": "ProofOfBallot2015",
339 | "minimumQuorumPercentage": "0.51",
340 | "minimumVotePercentage": "0.67",
341 | "approvedSigner": [
342 | "https://regulator-a.gov/i/bank-oversight",
343 | "https://regulator-b.gov/i/consumer-protection",
344 | "https://bank-x.com/i/housing",
345 | "https://bank-y.com/i/corporate-loans",
346 | "https://bank-z.com/i/swaps",
347 | ]
348 | },
349 | "signature": {
350 | "type": "LinkedDataSignature2016",
351 | "created": "2017-01-24T02:10:21Z",
352 | "creator": "lux:keys:d52aff68923f3b2c8183bd",
353 | "signatureValue": "FqT/yK90D4cPiwd/GFzv...NJGL=="
354 | }
355 | }
356 |
357 |
358 |
359 |
361 | MerkleTree
362 |
363 | A storage mechanism utilizing the
364 | Merkle Tree
365 | data structure, which enables efficient and secure verification of the
366 | contents of large data structures. The Bitcoin blockchain utilizes Merkle trees
367 | in its implementation.
368 |
369 |
370 | - Status
371 | - unstable
372 | - Parent Class
373 | - owl:Thing
374 | - Used by
375 | - storageMechanism
376 |
377 |
378 | The example below describes a ledger storage event where the storage mechanism
379 | is a Merkle tree:
380 |
381 |
382 | {
383 | "@context": [
384 | "https://w3id.org/flex/v1",
385 | "https://w3id.org/cryptocurrencies/v1"
386 | ],
387 | "id": "bytecoin:block:23fa73bb201c738d",
388 | "type": "LedgerConfigurationEvent",
389 | "storageMechanism": "MerkleTree",
390 | "consensusAlgorithm": {
391 | "type": "ProofOfWork2016",
392 | "proofOfWorkAlgorithm": "Bitcoin",
393 | "targetDifficulty": "199312067531.243"
394 | },
395 | "signature": {
396 | "type": "LinkedDataSignature2016",
397 | "created": "2017-01-24T02:10:21Z",
398 | "creator": "bytecoin:keys:23f3b2c8183bdd52aff689",
399 | "signatureValue": "90D4cFqT/yKPiwd/GFzv...NJGL=="
400 | }
401 | }
402 |
403 |
404 |
405 |
407 | SequentialList
408 |
409 | A data structure that stores a sequential list of items, also known as a
410 | linked list.
411 |
412 |
413 | - Status
414 | - unstable
415 | - Parent Class
416 | - owl:Thing
417 | - Used by
418 | - storageMechanism
419 |
420 |
421 | The example below describes a ledger configuration event where the storage
422 | mechanism is a sequential list:
423 |
424 |
425 | {
426 | "@context": "https://w3id.org/flex/v1",
427 | "id": "https://vhda.va.us.gov/ledgers/webville/houses/1",
428 | "type": "LedgerConfigurationEvent",
429 | "storageMechanism": "SequentialList",
430 | "consensusAlgorithm": {
431 | "type": "ProofOfSignature2016",
432 | "approvedSigner": "https://webville.va.us.gov/i/planning-department",
433 | "minimumSignaturesRequired": 1
434 | },
435 | "nextEvent": "https://vhda.va.us.gov/ledgers/webville/houses/2",
436 | "signature": {
437 | "type": "LinkedDataSignature2016",
438 | "created": "2016-02-21T02:10:21Z",
439 | "creator": "https://webville.va.us.gov/i/planning-department/keys/1",
440 | "signatureValue": "cNJGLFqT/d/90D4GFzv...yKPiw=="
441 | }
442 | }
443 |
444 |
445 |
446 |
447 |
448 |
591 | Properties
592 |
593 |
595 | addsObject
596 |
597 | Denotes that one or more objects have been added as a result of the event.
598 | This property is typically used by LedgerStorageEvents.
599 |
600 |
601 | - Status
602 | - unstable
603 | - Range
604 | - Thing
605 |
606 |
607 | The example below expresses a ledger storage event where an object
608 | describing a real estate loan transfer is added to the ledger.
609 |
610 |
611 | {
612 | "@context": [
613 | "https://w3id.org/flex/v1",
614 | "https://w3id.org/real-estate/v1"
615 | ],
616 | "id": "https://example-consortium.com/private-ledgers/loans/real-estate/2",
617 | "type": "LedgerStorageEvent",
618 | "previousEvent": "https://example-consortium.com/private-ledgers/loans/real-estate/1",
619 | "addsObject": [{
620 | "id": "https://example-consortium.com/private-ledgers/loans/real-estate/transactions/238947234",
621 | "transaction": {
622 | "source": "lei:HB7FFAZIO0MZ8PP8OE26", // compliant to ISO 17442 standard
623 | "destination": "lei:PP8OEHB7FFAZIO0MZ826",
624 | "transfer": {
625 | "loanId": "lei:FAZIO0PP8OEHB7FMZ826"
626 | }
627 | }
628 | }],
629 | "signature": [{
630 | "type": "LinkedDataSignature2016",
631 | "created": "2018-04-16T19:34:18Z",
632 | "creator": "https://regulator-b.gov/i/consumer-protection/keys/2f73",
633 | "signatureValue": "Piw90D4cFqT/yKd/JGLv...NGFz=="
634 | }, ... // there will be at least 3 more signatures here
635 | ]
636 | }
637 |
638 |
639 |
640 |
642 | approvedSigner
643 |
644 | Specifies an entity that is authorized to assert consensus under
645 | permissioned consensus algorithms. It is important to note that the data,
646 | such as public key material, should be stored in the ledger to ensure
647 | long-term auditability of the ledger.
648 |
649 |
650 | - Status
651 | - unstable
652 | - Range
653 | - URL
654 |
655 |
656 | The example below describes a ledger configuration event with a proof of
657 | signature consensus algorithm. The proof of signature only requires one
658 | approved signer, which is
659 | https://webville.va.us.gov/i/planning-department.
660 |
661 |
662 | {
663 | "@context": "https://w3id.org/flex/v1",
664 | "id": "https://vhda.va.us.gov/ledgers/webville/houses/1",
665 | "type": "LedgerConfigurationEvent",
666 | "storageMechanism": "SequentialList",
667 | "consensusAlgorithm": {
668 | "type": "ProofOfSignature2016",
669 | "approvedSigner": "https://webville.va.us.gov/i/planning-department",
670 | "minimumSignaturesRequired": 1
671 | },
672 | "nextEvent": "https://vhda.va.us.gov/ledgers/webville/houses/2",
673 | "signature": {
674 | "type": "LinkedDataSignature2016",
675 | "created": "2016-02-21T02:10:21Z",
676 | "creator": "https://webville.va.us.gov/i/planning-department/keys/1",
677 | "signatureValue": "cNJGLFqT/d/90D4GFzv...yKPiw=="
678 | }
679 | }
680 |
681 |
682 |
683 |
684 |
686 | checkpointLog
687 |
688 | A URL pointing to a log file that when replayed can re-create the current
689 | state of the ledger.
690 |
691 |
692 | - Status
693 | - unstable
694 | - Range
695 | - URL
696 |
697 |
698 | The example below expresses a ledger checkpoint event with a checkpointLog
699 | located at https://example.org/ledgers/example/checkpoints/132.
700 |
701 |
702 | {
703 | "@context": "https://w3id.org/flex/v1",
704 | "id": "https://example.org/ledgers/example/6372463",
705 | "type": "LedgerCheckpointEvent",
706 | "checkpointLog": "https://example.org/ledgers/example/checkpoints/132",
707 | "checkpointLogHash": "urn:sha256:7fa3b9eaa8d92d2b87abf83d88a92ff23",
708 | "signature": [{
709 | "type": "LinkedDataSignature2016",
710 | "created": "2018-04-16T19:34:18Z",
711 | "creator": "https://example.org/i/master/keys/32",
712 | "signatureValue": "Piw90D4cFqT/yKd/JGLv...NGFz=="
713 | }, ... // there may be multiple counter-signatures here
714 | ]
715 | }
716 |
717 |
718 |
719 |
721 | checkpointLogHash
722 |
723 | A cryptographic hash of the contents of the checkpointLog that may be
724 | used to ensure data integrity.
725 |
726 |
727 | - Status
728 | - unstable
729 | - Range
730 | - URI
731 |
732 |
733 | The example below expresses a ledger checkpoint event with a checkpointLog
734 | located at https://example.org/ledgers/example/checkpoints/132
735 | where the contents of the log should hash to a SHA-256 value of
736 | 7fa3b9eaa8d92d2b87abf83d88a92ff23.
737 |
738 |
739 | {
740 | "@context": "https://w3id.org/flex/v1",
741 | "id": "https://example.org/ledgers/example/6372463",
742 | "type": "LedgerCheckpointEvent",
743 | "checkpointLog": "https://example.org/ledgers/example/checkpoints/132",
744 | "checkpointLogHash": "urn:sha256:7fa3b9eaa8d92d2b87abf83d88a92ff23",
745 | "signature": [{
746 | "type": "LinkedDataSignature2016",
747 | "created": "2018-04-16T19:34:18Z",
748 | "creator": "https://example.org/i/master/keys/32",
749 | "signatureValue": "Piw90D4cFqT/yKd/JGLv...NGFz=="
750 | }, ... // there may be multiple counter-signatures here
751 | ]
752 | }
753 |
754 |
755 |
756 |
758 | consensusAlgorithm
759 |
760 | Used to specify a particular consensus algorithm, typically used in a
761 | ConfigurationEvent.
762 |
763 |
764 | - Status
765 | - unstable
766 | - Range
767 | - ConsensusAlgorithm
768 |
769 |
770 | The example below expresses a proof of signature consensus algorithm. This
771 | information is typically expressed in a ledger configuration event.
772 |
773 |
774 | {
775 | "@context": "https://w3id.org/flex/v1",
776 | "consensusAlgorithm": {
777 | "type": "ProofOfSignature2016",
778 | "approvedSigner": [
779 | "https://fema.example.us.gov/i/ofp",
780 | "https://tsa.example.us.gov/i/vclaims",
781 | "https://dhs.example.us.gov/i/credentialing"
782 | ],
783 | "minimumSignaturesRequired": 2
784 | }
785 | }
786 |
787 |
788 |
789 |
791 | minimumQuorumPercentage
792 |
793 | The minimum percentage of members in a particular balloting initiative that
794 | are required to vote in order for the vote to count.
795 |
796 |
797 | - Status
798 | - unstable
799 | - Range
800 | - xsd:string
801 |
802 |
803 | The example below expresses a ledger configuration event that specifies
804 | a proof of ballot consensus algorithm where the minimum percentage to
805 | achieve quorum is 51%.
806 |
807 |
808 | {
809 | "@context": [
810 | "https://w3id.org/flex/v1",
811 | "https://w3id.org/cryptocurrencies/v1"
812 | ],
813 | "id": "https://example-consortium.com/private-ledgers/loans/real-estate/1",
814 | "type": "LedgerConfigurationEvent",
815 | "storageMechanism": "SequentialList",
816 | "consensusAlgorithm": {
817 | "type": "ProofOfBallot2015",
818 | "minimumQuorumPercentage": "0.51",
819 | "minimumVotePercentage": "0.67",
820 | "approvedSigner": [
821 | "https://regulator-a.gov/i/bank-oversight",
822 | "https://regulator-b.gov/i/consumer-protection",
823 | "https://bank-x.com/i/housing",
824 | "https://bank-y.com/i/corporate-loans",
825 | "https://bank-z.com/i/swaps",
826 | ]
827 | },
828 | "signature": [{
829 | "type": "LinkedDataSignature2016",
830 | "created": "2018-04-16T19:34:18Z",
831 | "creator": "https://regulator-b.gov/i/consumer-protection/keys/2f73",
832 | "signatureValue": "Piw90D4cFqT/yKd/JGLv...NGFz=="
833 | }, ... // there will be at least 3 more signatures here
834 | ]
835 | }
836 |
837 |
838 |
839 |
840 |
842 | minimumSignaturesRequired
843 |
844 | The minimum number of signatures required to bind a particular decision made
845 | in a ledger.
846 |
847 |
848 | - Status
849 | - unstable
850 | - Range
851 | - xsd:positiveInteger
852 |
853 |
854 | The example below expresses a ledger configuration event specifying a
855 | proof of signature consensus algorithm where only one signature is required
856 | from the set of approved signers.
857 |
858 |
859 | {
860 | "@context": "https://w3id.org/flex/v1",
861 | "id": "https://vhda.va.us.gov/ledgers/webville/houses/1",
862 | "type": "LedgerConfigurationEvent",
863 | "storageMechanism": "SequentialList",
864 | "consensusAlgorithm": {
865 | "type": "ProofOfSignature2016",
866 | "approvedSigner": "https://webville.va.us.gov/i/planning-department",
867 | "minimumSignaturesRequired": 1
868 | },
869 | "nextEvent": "https://vhda.va.us.gov/ledgers/webville/houses/2",
870 | "signature": {
871 | "type": "LinkedDataSignature2016",
872 | "created": "2016-02-21T02:10:21Z",
873 | "creator": "https://webville.va.us.gov/i/planning-department/keys/1",
874 | "signatureValue": "cNJGLFqT/d/90D4GFzv...yKPiw=="
875 | }
876 | }
877 |
878 |
879 |
880 |
882 | minimumVotePercentage
883 |
884 | The minimum percentage of votes in an election to carry a particular
885 | motion under consideration.
886 |
887 |
888 | - Status
889 | - unstable
890 | - Range
891 | - xsd:string
892 |
893 |
894 | The example below expresses a ledger configuration event specifying a
895 | proof of ballot consensus algorithm where 67% of the vote is required to
896 | pass a motion.
897 |
898 |
899 | {
900 | "@context": [
901 | "https://w3id.org/flex/v1",
902 | "https://w3id.org/cryptocurrencies/v1"
903 | ],
904 | "id": "https://example-consortium.com/private-ledgers/loans/real-estate/1",
905 | "type": "LedgerConfigurationEvent",
906 | "storageMechanism": "SequentialList",
907 | "consensusAlgorithm": {
908 | "type": "ProofOfBallot2015",
909 | "minimumQuorumPercentage": "0.51",
910 | "minimumVotePercentage": "0.67",
911 | "approvedSigner": [
912 | "https://regulator-a.gov/i/bank-oversight",
913 | "https://regulator-b.gov/i/consumer-protection",
914 | "https://bank-x.com/i/housing",
915 | "https://bank-y.com/i/corporate-loans",
916 | "https://bank-z.com/i/swaps",
917 | ]
918 | },
919 | "signature": [{
920 | "type": "LinkedDataSignature2016",
921 | "created": "2018-04-16T19:34:18Z",
922 | "creator": "https://regulator-b.gov/i/consumer-protection/keys/2f73",
923 | "signatureValue": "Piw90D4cFqT/yKd/JGLv...NGFz=="
924 | }, ... // there will be at least 3 more signatures here
925 | ]
926 | }
927 |
928 |
929 |
930 |
931 |
933 | nextEvent
934 |
935 | The next event in a ledger. It is not always possible to know what the
936 | next event is for ledgers of a certain type.
937 |
938 |
939 | - Status
940 | - unstable
941 | - Range
942 | - URL
943 |
944 |
945 | The example below expresses a ledger event where the next event
946 | (https://vhda.va.us.gov/ledgers/webville/houses/2) is known.
947 |
948 |
949 | {
950 | "@context": "https://w3id.org/flex/v1",
951 | "id": "https://vhda.va.us.gov/ledgers/webville/houses/1",
952 | "type": "LedgerConfigurationEvent",
953 | "storageMechanism": "SequentialList",
954 | "consensusAlgorithm": {
955 | "type": "ProofOfSignature2016",
956 | "approvedSigner": "https://webville.va.us.gov/i/planning-department",
957 | "minimumSignaturesRequired": 1
958 | },
959 | "nextEvent": "https://vhda.va.us.gov/ledgers/webville/houses/2",
960 | "signature": {
961 | "type": "LinkedDataSignature2016",
962 | "created": "2016-02-21T02:10:21Z",
963 | "creator": "https://webville.va.us.gov/i/planning-department/keys/1",
964 | "signatureValue": "cNJGLFqT/d/90D4GFzv...yKPiw=="
965 | }
966 | }
967 |
968 |
969 |
970 |
971 |
973 | previousEvent
974 |
975 | The previous event in a ledger. This is typically useful when auditing a
976 | ledger to ensure that its history is valid.
977 |
978 |
979 | - Status
980 | - unstable
981 | - Range
982 | - URL
983 |
984 |
985 | The example below expresses a ledger event where the previous event
986 | can be accessed at
987 | https://example-consortium.com/private-ledgers/loans/real-estate/1.
988 |
989 |
990 | {
991 | "@context": [
992 | "https://w3id.org/flex/v1",
993 | "https://w3id.org/housing/v1",
994 | ],
995 | "id": "https://vhda.va.us.gov/ledgers/webville/houses/2",
996 | "type": "LedgerStorageEvent",
997 | "previousEvent": "https://example-consortium.com/private-ledgers/loans/real-estate/1",
998 | "replacesObject": [{
999 | "id": "https://vhda.va.us.gov/properties/3829344",
1000 | "propertyAddress": {
1001 | "street": "263 Main Street",
1002 | "locality": "Webville",
1003 | "region": "VA",
1004 | "postalCode": "24736-3726",
1005 | "country": "US"
1006 | },
1007 | "owner": {
1008 | "name": "Jane Smith",
1009 | "postalAddress": { ... }
1010 | }],
1011 | "signature": {
1012 | "type": "LinkedDataSignature2016",
1013 | "created": "2016-02-22T02:10:21Z",
1014 | "creator": "https://webville.va.us.gov/i/planning-department/keys/1",
1015 | "signatureValue": "cNJGLFqT/d/90D4GFzv...yKPiw=="
1016 | }
1017 | }
1018 |
1019 |
1020 |
1021 |
1022 |
1024 | proofOfWorkAlgorithm
1025 |
1026 | This property is used to specify the type of proof of work algorithm that
1027 | the ledger expects to be executed in order to reach consensus.
1028 |
1029 |
1030 | - Status
1031 | - unstable
1032 | - Range
1033 | - URI
1034 |
1035 |
1036 | The example below expresses a proof of work consensus algorithm where the
1037 | specific algorithm is Bitcoin. Note that this property requires a
1038 | URL and Bitcoin is an alias for a URL like
1039 | https://example.com/algorithms/Bitcoin.
1040 |
1041 |
1042 | {
1043 | "@context": [ "https://w3id.org/flex/v1", "https://w3id.org/cryptocurrencies/v1" ],
1044 | "type": "ProofOfWork2016",
1045 | "proofOfWorkAlgorithm": "Bitcoin",
1046 | "targetDifficulty": "199312067531.243"
1047 | }
1048 |
1049 |
1050 |
1051 |
1053 | removesObject
1054 |
1055 | Used to specify the set of objects to remove during a StorageEvent.
1056 |
1057 |
1058 | - Status
1059 | - unstable
1060 | - Range
1061 | - Thing
1062 |
1063 |
1064 | The example below expresses a ledger storage event where an object
1065 | describing a real estate property is removed from the ledger. Note that a
1066 | removal doesn't remove the object from history, it only removes the object
1067 | from the active state in the state machine.
1068 |
1069 |
1070 | {
1071 | "@context": [
1072 | "https://w3id.org/flex/v1",
1073 | "https://w3id.org/housing/v1",
1074 | ],
1075 | "id": "https://vhda.va.us.gov/ledgers/webville/houses/2",
1076 | "type": "LedgerStorageEvent",
1077 | "previousEvent": "https://example-consortium.com/private-ledgers/loans/real-estate/1",
1078 | "removesObject": [{
1079 | "id": "https://vhda.va.us.gov/properties/3829344",
1080 | "propertyAddress": {
1081 | "street": "263 Main Street",
1082 | "locality": "Webville",
1083 | "region": "VA",
1084 | "postalCode": "24736-3726",
1085 | "country": "US"
1086 | },
1087 | "owner": {
1088 | "name": "Jane Smith",
1089 | "postalAddress": { ... }
1090 | }],
1091 | "signature": {
1092 | "type": "LinkedDataSignature2016",
1093 | "created": "2016-02-22T02:10:21Z",
1094 | "creator": "https://webville.va.us.gov/i/planning-department/keys/1",
1095 | "signatureValue": "cNJGLFqT/d/90D4GFzv...yKPiw=="
1096 | }
1097 | }
1098 |
1099 |
1100 |
1101 |
1103 | replacesObject
1104 |
1105 | Used to specify the set of objects to replace during a StorageEvent.
1106 |
1107 |
1108 | - Status
1109 | - unstable
1110 | - Range
1111 | - Thing
1112 |
1113 |
1114 | The example below expresses a ledger storage event where an object
1115 | describing a real estate property is replaced with new information.
1116 |
1117 |
1118 | {
1119 | "@context": [
1120 | "https://w3id.org/flex/v1",
1121 | "https://w3id.org/housing/v1",
1122 | ],
1123 | "id": "https://vhda.va.us.gov/ledgers/webville/houses/2",
1124 | "type": "LedgerStorageEvent",
1125 | "previousEvent": "https://example-consortium.com/private-ledgers/loans/real-estate/1",
1126 | "replacesObject": [{
1127 | "id": "https://vhda.va.us.gov/properties/3829344",
1128 | "propertyAddress": {
1129 | "street": "263 Main Street",
1130 | "locality": "Webville",
1131 | "region": "VA",
1132 | "postalCode": "24736-3726",
1133 | "country": "US"
1134 | },
1135 | "owner": {
1136 | "name": "Jane Smith",
1137 | "postalAddress": { ... }
1138 | }],
1139 | "signature": {
1140 | "type": "LinkedDataSignature2016",
1141 | "created": "2016-02-22T02:10:21Z",
1142 | "creator": "https://webville.va.us.gov/i/planning-department/keys/1",
1143 | "signatureValue": "cNJGLFqT/d/90D4GFzv...yKPiw=="
1144 | }
1145 | }
1146 |
1147 |
1148 |
1149 |
1150 |
1152 | storageMechanism
1153 |
1154 | Denotes the type of storage mechanism that should be used for this ledger.
1155 | These storage mechanisms often have qualities that the ledger depends on
1156 | for integrity checking, storage efficiency, or other qualities that are
1157 | important to the ledger application.
1158 |
1159 |
1160 | - Status
1161 | - unstable
1162 | - Range
1163 | - URI
1164 |
1165 |
1166 | The example below expresses a ledger configuration event where the storage
1167 | mechanism is a sequential list.
1168 |
1169 |
1170 | {
1171 | "@context": "https://w3id.org/flex/v1",
1172 | "id": "https://vhda.va.us.gov/ledgers/webville/houses/1",
1173 | "type": "LedgerConfigurationEvent",
1174 | "storageMechanism": "SequentialList",
1175 | "consensusAlgorithm": {
1176 | "type": "ProofOfSignature2016",
1177 | "approvedSigner": "https://webville.va.us.gov/i/planning-department",
1178 | "minimumSignaturesRequired": 1
1179 | },
1180 | "nextEvent": "https://vhda.va.us.gov/ledgers/webville/houses/2",
1181 | "signature": {
1182 | "type": "LinkedDataSignature2016",
1183 | "created": "2016-02-21T02:10:21Z",
1184 | "creator": "https://webville.va.us.gov/i/planning-department/keys/1",
1185 | "signatureValue": "cNJGLFqT/d/90D4GFzv...yKPiw=="
1186 | }
1187 | }
1188 |
1189 |
1190 |
1191 |
1192 |
1194 | targetDifficulty
1195 |
1196 | A property that specifies how difficult a particular proof of work should be.
1197 | The value is dependent on the proofOfWorkAlgorithm property.
1198 |
1199 |
1200 | - Status
1201 | - unstable
1202 | - Range
1203 | - xsd:string
1204 |
1205 |
1206 | The example below expresses a Bitcoin proof of work consensus algorithm where
1207 | the target difficulty is 199312067531.243.
1208 |
1209 |
1210 | {
1211 | "@context": "https://w3id.org/flex/v1",
1212 | "type": "ProofOfWork2016",
1213 | "proofOfWorkAlgorithm": "Bitcoin",
1214 | "targetDifficulty": "199312067531.243"
1215 | }
1216 |
1217 |
1218 |
1219 |
1244 |
1245 |
1246 |
1247 |
1248 | 
155 | 
173 | 
187 | 
200 | 
227 | 
245 |