Off-chain Data Fetching Architecture for Ethereum Smart Contract

Ethereum smart contract makes developers can deploy decentralized applications to inherit features from blockchain, such as decentralization and openness. Although Ethereum provided a decentralized platform, Ethereum Virtual Machine for smart contracts, it lacks of ability to fetch off-chain data. The general solution is Oracle data carrier. However, Oracle results in rising deployment costs. It requires Ethereum smart contract developers to follow format in programing contract, this constraint decreases the readability of smart contract. This paper proposes an off-chain data fetching architecture which is cost-effective and highly elastic for smart contract. It also compatible with exited contract, which makes Ethereum smart contract owner able to automate the reply process.