Efficient Off-Chain Data Feed Mechanism Using a Novel Blockchain Oracle Network Combined With Directed Acyclic Graph Distributed Ledger

Smart contracts were introduced as autonomous programs running across a blockchain network. To solve the difficulty that smart contracts on the blockchain cannot interact with the real world, some blockchain oracle implementation schemes have been proposed. However, the existing data feed schemes still cannot meet the demand of off-chain intensive data feed. This paper introduces a directed acyclic graph (DAG)-distributed ledger into the blockchain oracle data feed scheme, to propose a DAG-distributed ledger-based decentralized oracle network (DDON) framework. The lightweight DAG consensus mechanism ensures data integrity and significantly reduces the entry of valueless information into the DDON, ultimately generating deterministic data. The proposed DAG structure enables parallel processing of transactions and accelerates the efficiency of data feeds. This also enables the feeding of historical data. In addition, an off-chain data feed mechanism is designed for off-chain intensive streaming of data feeds through the proposed oracle network, to separate data feeds from data fetches and improve the efficiency of feeding multiple requests. The evaluation results and discussions demonstrate that the proposed framework reduces the response time for every smart contract request and is more efficient and flexible than other mainstream oracle data feed services.