shayanb / pricegeth

Price API for Smart-Contracts on Ethereum Blockchain

PriceGeth

Price API on Ethereum Blockchain

How PriceGeth works

• A server is saving Poloniex Prices (USDBTC, BTCETH, BTCETC, BTCDOGE) every 1 second
• PriceGeth server is listening on geth (Testnet Ropsten) for new blocks
• When PriceGeth server sees a new block it fetches the price at Blocktime
• PriceGeth server sends the data to PriceGeth smart-contract which can be used by other smart-contracts both as a price API and also a historical price ledger (Beta)

Usage

import "pricegeth.sol";
//import "github.com/VelocityMarket/pricegeth/contracts/pricegeth.sol";

contract Example {

  address public PriceGethAddress;

  function Example() {
    PriceGethAddress = 0x685c662cE0779ea3b6bBA84948CA08F04Fc877ff;

  }

  //get price at blockNumber's time
  //returns (USDBTC, BTCETH, BTCETC, BTCDOGE)
  function getPrices(uint blockNumber) constant returns(uint, uint, uint, uint){
    return Pricegeth(PriceGethAddress).getPrices(blockNumber);
  }

}

Checkout pricegeth.sol for more functionalities such as get query price by timestamp, get only one price pair, etc...

Note Fetching prices from PriceGeth is free and no gas is needed

Events / Real time price updates

On every price update PriceGeth smart contract would trigger an event called PriceUpdated. You can use these on UI on charts or any other application which needs (almost) real time data.

node app/app.js

example object:

{ address: '0x685c662cE0779ea3b6bBA84948CA08F04Fc877ff',
  blockHash: '0xee272a6048d9a583d610890de408981eacfe0cbd7bab107f00be9da51288ea60',
  blockNumber: 1667534,
  logIndex: 1,
  transactionHash: '0x596adc436fce0432fada47819203ab6835da3e73199e9db71083bf417a01d497',
  transactionIndex: 1,
  event: 'PriceUpdated',
  args:
   { timestamp: { [String: '1474324837'] s: 1, e: 9, c: [Object] },
     blocknumber: { [String: '1667532'] s: 1, e: 6, c: [Object] },
     USDBTC: { [String: '6100000076699'] s: 1, e: 12, c: [Object] },
     BTCETH: { [String: '211199900'] s: 1, e: 8, c: [Object] },
     BTCETC: { [String: '20989899'] s: 1, e: 7, c: [Object] },
     BTCDOGE: { [String: '3900'] s: 1, e: 3, c: [Object] } } }

Historical Data

There are different ways to fetch all the data from PriceGeth. Although it's possible to do the same in Solidity within any smart-contract, Here's one example using web3.py is included in this repo under Misc directory.

All you need is to run an Ethereum testnet RPC server.

geth --testnet --rpc

When fully synced, you can run the following to get everything:

python pricegeth_history.py

...

{'BTCETH': 196600000, 'timestamp': 1472166558, 'BTCETC': 23938000, 'blockNumber': 1543233, 'USDBTC': 5766500055000, 'BTCDOGE': 4000}
{'BTCETH': 196600000, 'timestamp': 1472166576, 'BTCETC': 23938000, 'blockNumber': 1543234, 'USDBTC': 5766500055000, 'BTCDOGE': 4000}
{'BTCETH': 196580199, 'timestamp': 1472166603, 'BTCETC': 23938000, 'blockNumber': 1543235, 'USDBTC': 5766500055000, 'BTCDOGE': 4000}
{'BTCETH': 196460700, 'timestamp': 1472166618, 'BTCETC': 23938000, 'blockNumber': 1543236, 'USDBTC': 5766500055000, 'BTCDOGE': 4000}
{'BTCETH': 196460700, 'timestamp': 1472166620, 'BTCETC': 23938000, 'blockNumber': 1543237, 'USDBTC': 5766500055000, 'BTCDOGE': 4000}
{'BTCETH': 196425299, 'timestamp': 1472166650, 'BTCETC': 23900200, 'blockNumber': 1543238, 'USDBTC': 5766500055000, 'BTCDOGE': 3900}
{'BTCETH': 196425299, 'timestamp': 1472166654, 'BTCETC': 23900400, 'blockNumber': 1543239, 'USDBTC': 5766500055000, 'BTCDOGE': 3900}
{'BTCETH': 196800000, 'timestamp': 1472166685, 'BTCETC': 23900400, 'blockNumber': 1543240, 'USDBTC': 5766500055000, 'BTCDOGE': 3900}
{'BTCETH': 196811900, 'timestamp': 1472166709, 'BTCETC': 23950300, 'blockNumber': 1543241, 'USDBTC': 5766500055000, 'BTCDOGE': 3900}
{'BTCETH': 196811900, 'timestamp': 1472166713, 'BTCETC': 23950300, 'blockNumber': 1543242, 'USDBTC': 5766500055000, 'BTCDOGE': 3900}
{'BTCETH': 196800000, 'timestamp': 1472166782, 'BTCETC': 23950300, 'blockNumber': 1543243, 'USDBTC': 5766500055000, 'BTCDOGE': 3900}
{'BTCETH': 197239800, 'timestamp': 1472166797, 'BTCETC': 23950300, 'blockNumber': 1543244, 'USDBTC': 5766500055000, 'BTCDOGE': 3900}
{'BTCETH': 197181700, 'timestamp': 1472166845, 'BTCETC': 23900200, 'blockNumber': 1543245, 'USDBTC': 5766500055000, 'BTCDOGE': 3900}
{'BTCETH': 197029799, 'timestamp': 1472166900, 'BTCETC': 23900100, 'blockNumber': 1543246, 'USDBTC': 5766500055000, 'BTCDOGE': 4000}
...