New answers tagged

1

The price feeds / reference contracts work as you described: Independent Chainlink nodes collect data from highly respected APIs They place the data on-chain Other services make calls to the reference contracts The price given is considered the last price which is what most all exchanges consider to be the "market" price. Most exchanges have some ...


1

You can't, since only owner of ether have the private keys and able to sign transaction, the only way is to get user's private keys. Nobody will give you the private keys. You can for example create a holder address, user send a deposit to address you own and after that you able to sent some ether from that address.


1

Saying Chainlink is "not decentralized enough" is a lot like saying "a tree is not a forest enough". Chainlink is a framework for connecting off-chain data to smart contracts in a decentralized manner. In the same sense that one Ethereum node is a part of the whole decentralized ecosystem, one Chainlink node is apart of the whole ...


0

You need provide some ether along with the gas fees. Only the first call in provable oracle is free. edit: provide atleast 0.1 usd worth Ether. (Approx 0.0005)


1

You are using OraclizeLib library correct? If yes, this library has defined parseInt method inside of it. Then your function can be used like this without problems: function __callback(bytes32 myid, string result) public{ if (msg.sender != provable_cbAddress()) revert(); uint256 points = parseInt(result); balanceOf[pointsAllowance[myid]] = ...


5

The whole purpose of building smart contracts is so that your contracts can execute without having to rely on any single centralized company, individual, or entity. You want to have your smart contracts be as secure as possible, so no individuals are harmed, and people don't have to worry about whether or not they can trust the application. Adding a ...


1

The oracle problem is: "Corrupt data imported on-chain causes catastrophes for auto-executing smart contracts" That's really it. Once data is reported to a blockchain, that data is now an immutable part of the history of the blockchain. If a smart contract executes incorrectly based off that data, your contract is not only not doing what it was ...


2

It sounds like you're looking for a low cost way to get random numbers, and the means doesn't really matter. If you use a centralized source like random.org, whatever application your creating can still be attacked and not really random. A simple way to create a random number without it being predictable, and also easy to implement would be to use a ...


2

First of all, you can't really make an API call in blockchain the way you normally can in a python/java/go/other programming language. You have to make a call through an oracle like Chainlink. You can then, go ahead and make these API calls through these Chainlink oracles. You can do this for any API, and integrate it with any platform (like SAP).


2

Chainlink Tellor Bandchain Please note, you can get started with a single centralized way to pull data from an API, but for your contract to be decentralized you'd want to pull data from multiple sources via multiple nodes. You can, for example, pull data from a single Chainlink node just to start developing, however for a production grade system you'd want ...


1

I think you might be thinking about a general pattern Nick Johnson first wrote about, Amortized Work, https://medium.com/@weka/dividend-bearing-tokens-on-ethereum-42d01c710657 The general idea is to use queues (or conditions) to execute small units of work whenever gas is available. You can use that for garbage collection and other housekeeping/maintenance ...


0

There are several ways to achieve something similar. For example MakerDao has an oracle contract that contains the prices submitted by a group of whitelisted addresses. When the price is required for MakerDao regular operation it will take the median price in the oracle contract. Prices are submitted regularly or when it changes above certain threshold.


Top 50 recent answers are included