IPVS/AS Using Triples as the Data Model for Blockchain Systems Dennis Przytarski
Agenda • Motivation • Our approach • Evaluation • Example Dennis Przytarski • Using Triples as the Data Model for Blockchain Systems 2
Motivation Blockchain Systems • Initially designed for cryptocurrencies • Simple and fixed data model • Other scenarios • Automotive • Full history of a vehicle • Real Estate • Record of land titles • Voting • Reduce voter fraud Dennis Przytarski • Using Triples as the Data Model for Blockchain Systems 3
Motivation Blockchain Systems • Key-value data model latest application state World State • Simple query engine queries Query • World state Key-value store Engine (Document store) • Scenarios is derived from • Transportation/Trucking Ledger • Tracking journey stops, Blockchain parcel service • Supply Chain Integrity Block n-2 Block n-1 Block n • Food chain, Header Header Header waste management TRXN TRXN TRXN ... ... ... • Requirements • Flexible information model • Query engine for Transaction • World state • History (analytics, audit trails) Key Value Example key value ... ... CAR0 {color :“ blue “, make :“Ford“} based on [1] Dennis Przytarski • Using Triples as the Data Model for Blockchain Systems 4
Merge Blockchain and Database Systems BLOCKCHAIN SYSTEMS DATABASE SYSTEMS • immutability • generic but flexible data model • tamper-resistance • powerful query engine DESIGN REQUIREMENTS • maintain a flexible information model and an efficient data representation • support a powerful query engine • preserve the integrity of the blockchain‘s data structure (tamper-resistance) Dennis Przytarski • Using Triples as the Data Model for Blockchain Systems 5
Data Model • Key-value • values are often serialized • if key is not known, a full scan is necessary • no powerful query engine, just get / set operations • Relational • too strict for immutable data • schemas evolve over time leading to schema changes • Triples • flexible schemas without maintaining an one-size-fits-all schema • triples are facts data of interest are easier to extract Dennis Przytarski • Using Triples as the Data Model for Blockchain Systems 6
Merkle B-Tree Hash A … Root node Pointer Hash B Pointer Hash C Pointer Hash D Data Data Data Node Hash B Hash C Hash D ’ • Pointer: Memory address • Hash: Hash over the node’s data [2]: The Merkle B-Tree: Li, Feifei, et al. "Dynamic authenticated index structures for outsourced databases." SIGMOD 2006. Dennis Przytarski • Using Triples as the Data Model for Blockchain Systems 7
Architecture latest application state World State queries Query Query Key-value store Engine Engine queries queries (Document store) historical latest application application is derived from state state Ledger Blockchain Blockchain Block n-2 Block n-1 Block n Block n-2 Block n-1 Block n Header Header Header Header Header Header TRXN TRXN TRXN ... ... ... latest application state Transaction Merkle B-tree entity attribute value Example Key Value <Triple> Example key value CAR0 car/color blue ... ... ... CAR0 {color :“ blue “, make :“Ford“} CAR0 car/make Ford Dennis Przytarski • Using Triples as the Data Model for Blockchain Systems 8
Advantage (1/2) Replace three data stores by one Blockchain Block n-3 Block n-2 Block n-1 Block n Header Header Header Header TRXN TRXN TRXN TRXN ... ... ... ... Storage Architecture Analytics World State Blockchain Blockchain Transaction log Graph database Key-value store Triplestore on file system is is Relational database (Document store) exported derived from from replaced by Ledger Dennis Przytarski • Using Triples as the Data Model for Blockchain Systems 9
Advantage (2/2) Built-in Data Integrity Checks (Tamper-resistance) • The database systems ‚Analytics‘ and ‚World State‘ are not aware of the blockchain‘s data structure data integrity checks must be done manually Query Query Query Engine Engine Engine if needed if needed built-in data data integrity data integrity integrity checks checks are checks are (tamper-resistance) done manually done manually Analytics World State Blockchain Blockchain Transaction log Graph database Key-value store Triplestore on file system is is Relational database (Document store) exported derived from from Ledger Dennis Przytarski • Using Triples as the Data Model for Blockchain Systems 10
Problem • High storage requirements • Optimization mechanisms ( efficient storage techniques) • data compression • data encoding • reuse of already stored data structures Dennis Przytarski • Using Triples as the Data Model for Blockchain Systems 11
Example Transaction 1 Transaction 2 <B9F, name , „Pluto“> <B9F, type, „ dwarf_planet “> <B9F, type, „planet“> Block 1 Block 2 The query engine uses Hash 2F7 the Merkle B-trees of a Hash FC8 4 1 block to compute the Node AEV AEV A <= name A <= name result of a query Nodes are Hash FAA Hash E87 Hash E87 Hash C29 2 2 5 3 stored in a <B9F, name , „Pluto“> <B9F, type, „planet“> <B9F, name , „Pluto“> <B9F, type, „ dwarf_planet “> … … … … key-value store Key Value Root of identical node after FC8 1 first block Query Block 1 E87 2 SELECT ?type ASOF n FAA 3 WHERE Query result Root of 4 2F7 [ ?object name „Pluto“] for n =1 : ?type is planet second block after C29 5 [ ?object type ?type ] for n =2 : ?type is dwarf_planet Block 2 Dennis Przytarski • Using Triples as the Data Model for Blockchain Systems 12
Contact Details Thank you! University of Stuttgart IPVS/AS Dennis Przytarski Email: Dennis.Przytarski@ipvs.uni-stuttgart.de Dennis Przytarski • Using Triples as the Data Model for Blockchain Systems 13
References • [1]: Androulaki, Elli, et al. "Hyperledger fabric: a distributed operating system for permissioned blockchains." Proceedings of the Thirteenth EuroSys Conference. ACM, 2018. • [2]: Li, Feifei, et al. "Dynamic authenticated index structures for outsourced databases." Proceedings of the 2006 ACM SIGMOD international conference on Management of data. ACM, 2006. • Merkle, Ralph C. "A digital signature based on a conventional encryption function." Conference on the theory and application of cryptographic techniques. Springer, Berlin, Heidelberg, 1987. • C. Mohan, Tutorial: Blockchains and Databases (VLDB 2017) Dennis Przytarski • Using Triples as the Data Model for Blockchain Systems 14
Recommend
More recommend
