Smart contracts requirements may need to do actions depending on results of real world events and don’t have any native way to communicate with data on the internet. In the context of blockchains, the oracle pattern is the principle of linking real world data that lives outside of the blockchain to actors living inside the blockchain: mainly smart contracts that consumes data in order to decide which action to take.
We published an article that present the basics of what is an oracle and how to implement one for the Ethereum blockchain. In this article you’ll see different uses cases and where to use an Oracle. We also cover a simple oracle implementation in Solidity that mimic a basic insurance contract on the blockchain.
As Oracle can take many forms, our second article explains how to use the Oraclize platform to fetch data from the internet and use it in your smart contract. Our example shows how to fetch the current USD price of Ethereum from a web API.