Ask Ξ Community: What do you think of our new smart contract, PriceFeed?

romanm

Hey Ether Enthusiasts,

We have designed a bot that pumps real market values
into an Ethereum smart contract, you can see it here:

http://feed.ether.camp

Now you have the option to build new Ethereum smart contracts on top
of real world values. If you prefer to work in a trust-less environment we
will show you how you can create your own bot that will do it based upon
your variables.

What do you think ? (back to reddit comments)

===========================

How to access it from your own contract ?
All you need is couple of lines of code:

PriceFeedApi priceFeed = PriceFeedApi(named("ether-camp/price-feed"));
uint price = priceFeed.getPrice("USDT_ETH")

and the contract interface:

contract PriceFeedApi {
    
    function getPrice(bytes32 symbol) returns(uint currPrice);  
    function getTimestamp(bytes32 symbol) returns(uint timestamp);
}

[available symbols]
USDT_ETH, BTC_ETH, USDT_BTC,
EURUSD, GBPUSD, USDJPY, XAUUSD,
XAGUSD SP500, NASDAQ, AAPL, GOOG,
MSFT, GM, GE, WMT, F, T

Full invoke sample is here:
https://github.com/ether-camp/contracts/blob/master/PriceTest.sol


What do you think ? (back to reddit comments)

===================================================================

How to access it from your own web3 page ?

	 	 

       factory.price = function(symbol, callback) {
	 
	    var web3 = require('web3');                        
			
	    // you can set your own peer to handle this 
	    web3.setProvider(new web3.providers.HttpProvider('http://lb-frontier.ether.camp'));	 
			
	    var nameRegAbi = [{"constant":true,
			            "inputs"[{"name":"name","type":"bytes32"}],"name":"addressOf",
						"outputs":[{"name":"addr","type":"address"}],"type":"function"}];
  		    
            var nrAddress = "0x985509582b2c38010bfaa3c8d2be60022d3d00da";
            var Namereg = web3.eth.contract(nameRegAbi).at(nrAddress);
			
	    Namereg.addressOf.call("ether-camp/price-feed", function(err, pfAddress){            
			
	     var priceFeedAbi = [{"constant":true,
		         "inputs":
                            [{"name":"symbol","type":"bytes32"}],
                              "name":"getPrice",
			 "outputs":[{"name":"currPrice","type":"uint256"}],
                               "type":"function"},
			{"constant":true,"inputs":[{"name":"symbol","type":"bytes32"}],
                                "name":"getTimestamp",
			 "outputs":[{"name":"timestamp","type":"uint256"}],
                                "type":"function"}];
	     var PriceFeed = web3.eth.contract(priceFeedAbi).at(pfAddress);				
			
	     PriceFeed.getPrice.call(symbol, callback);						 	 		
	  });
}

[available symbols]
USDT_ETH, BTC_ETH, USDT_BTC,
EURUSD, GBPUSD, USDJPY, XAUUSD,
XAGUSD SP500, NASDAQ, AAPL, GOOG,
MSFT, GM, GE, WMT, F, T

What do you think ? (back to reddit comments)



P.S. on the open source ethereum bot , will post latter. we will post the open-source ethereum bot later




With love from
ether.camp

GeorgeHallam

This is great Roman!

ryepdx

That's pretty awesome! Good job.

romanm

Thanks

MichaelSmith

Awesome. Welcome to join our Ethereum dapp talk Skype group: https://join.skype.com/xe2D5Z3

MichaelSmith

Your service looks really useful.

JLilic

Great work Roman.

sillytuna

Given that it costs money to pump data in, and access to the data is free (or a rogue contract could redistribute for a lower price within the next block) - would this be some sort of voluntary/sponsorship model?

romanm

Well it's sounds like true in
the first glance but if you
watch the internet you see
ton of stuff that started with
similar model and somehow evolved
to a self sustainable service.

For us, we just experimenting
with different stuff that can be valuable
for people.

Cheers
Roman.

sillytuna

I love the idea and numerous people are talking about them. I've just been thinking how to make these things sustainable. Open data can be sponsored or gift funded; licensed data is another option- rogue contracts are then less trustworthy and incur expenses.

LarsPensjo

Could you please provide an example how to invoke this from geth console mode?

techie

LarsPensjo, here's a small example:

> var feed = eth.contract([{"constant":true,"inputs":[{"name":"symbol","type":"bytes32"}],"name":"getPrice","outputs":[{"name":"currPrice","type":"uint256"}],"type":"function"},{"constant":true,"inputs":[{"name":"symbol","type":"bytes32"}],"name":"getTimestamp","outputs":[{"name":"timestamp","type":"uint256"}],"type":"function"}]).at("0x1194e966965418c7d73a42cceeb254d875860356")
> feed.getPrice.call("BTC_ETH", console.log)
null 5132

You can call getPrice method with your own callback:

feed.getPrice.call("BTC_ETH", function(err, price) {
  console.log(err, price)
});

LarsPensjo

Thanks! I created a pretty print function to show the values in the accounts (for dollar and bitcoin). See checkAllBalances.

Current price mBTC/ether:0.005049 USD$/ether: 1.200002 at Thu, 10 Sep 2015 17:05:56 UTC

eth.accounts[0]: 0xXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX: 1507.654  ether,     ฿7.612, $1809.18
eth.accounts[1]: 0xXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX:        0    wei,         ฿0, $0
eth.accounts[2]: 0xXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX:    6.791 finney,         ฿0, $0
eth.accounts[3]: 0xXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX:   10.037  ether,      ฿0.05, $12.04

Total:                                                       1517.699  ether,  ฿7.662863, $1821.24

romanm

Thanks , sounds like it really works (OMG)

koeppelmann

Hey Roman - how often you will you update the feeds? If you do it reliable and regular we could use this contract as an possible oracle for Gnosis.

romanm

Hey Marty, the short answer is we send an update tx each 10 minutes, but it is not all, the catch is that we also test our new core on that bot so you will see sometimes lose of updates, and long periods of the same data.

So this being said my suggestion would be try to use that but do not publicate ot to wide, let us take some time and established more reliable service.

romanm

we take the quote from poloniex public API so signed or not it is pretty good level of trust

koeppelmann

actually I think soon most data feeds will just provide signed data off chain. And only if needed by a DAPP they will be written to the blockchain. USD/ETH and a few others might be an exception since they might be used very frequent.