August 2018
Intermediate to advanced
404 pages
11h 19m
English
Content preview from Ethereum Cookbook
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How to do it...
- Solidity does not allow you to pull data from an external API source. Use an Oracle service to achieve this functionality.
- An oracle is an event listener that listens and responds to them by sending the results of a query back to the contract. In this way, contracts can interact with the external world.
- As an example, assume that we have a smart contract that uses an external data service to select a random number. Let's see how we can implement it using a custom Oracle service.
- Create a basic smart contract with a state variable to store the random number:
pragma solidity ^0.4.24;contract OracleRng { uint public random; ...}
- The Oracle service listens to the event logged in the contract and then uses the log details to ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.