Oracle Machine Technology Depth Analysis

The Oracle Machine is a key infrastructure in the blockchain ecosystem that can provide off-chain data for smart contracts. As a bridge connecting smart contracts to the external world, the Oracle Machine plays an indispensable role in blockchain applications.

Smart contracts on Ethereum cannot directly obtain off-chain information, such as the trading volume of crude oil on a specific day. This is when an Oracle Machine is needed to intervene and transmit the required data to the smart contract. The specific process is as follows: the contract writes the data requirements into the event log, the off-chain program listens for this event and retrieves the corresponding data, and then uploads the data to the chain by calling the contract method.

Among the many Oracle Machine projects, Chainlink has the largest market share. It has built a well-incentivized ecosystem through the LINK token. The triggering of Chainlink Oracle Machines requires the transfer of LINK tokens, which falls under the request-response model.

The LINK token adopts the ERC677 standard, which adds the transferAndCall method based on ERC20. This method combines payment and service requests into one, making it very suitable for the business scenarios of Oracle Machine. When a user calls transferAndCall, in addition to the transfer, it will also trigger the onTokenTransfer method of the receiving contract.

In the Oracle Machine contract, the onTokenTransfer method performs a series of security checks, including verifying the token, data length, etc. After the checks, it calls the oracleRequest method to process the request. This method generates a unique requestId, sets an expiration time, and emits an OracleRequest event containing the request details.

After the off-chain node listens to the event, it will parse the request information and obtain the required data via API. Then the node calls the fulfillOracleRequest method to submit the data to the blockchain. This method, after verifying the validity of the request, will call the callback function of the requester's contract to return the data.

For developers, Chainlink also provides a more convenient price Oracle Machine service. Each trading pair has a dedicated Price Feed contract that can directly query the latest price. Most application scenarios only need to call the latestRoundData method to obtain the latest price data.

Overall, Oracle Machine technology has opened up data channels between the blockchain and the outside world, providing more possibilities for the application scenarios of smart contracts. As a blockchain infrastructure, the importance of Oracle Machines is self-evident, and their development will profoundly impact the entire blockchain ecosystem.