5

Ultimately you're going to be relying on somebody to tell the truth, because somebody is going to have to be in charge of the thermometer. The information from the thermometer then needs to be transmitted to your Ethereum contract in such a way that the contract can believe it came from the thermometer: Some computer somewhere owned by someone will either ...


4

Edmund Edgar from Reality Keys here. Reality Keys provides signed data for ETH vs Euro (and various other currencies) which you can feed into a smart contract. This is what's powering EtherOpt, the decentralized options exchange. Source code here. The Eth price is coming from Poloniex, but these feeds are actively maintained rather than just making the ...


4

I have recently created an unoffical python library and scriptable cli for etherchain.org called pyetherchain that gives you access to submitted solidity contract source-code including (experimental) abi-decoded constructor arguments/transactions. The abi-decoded inputs help you understand how contracts/people are interacting with the smart contract. ...


3

The web3 JS API has a getCode function that allows you to access the bytecode of the contract - that was deployed to the blockchain at the given address. It should be possible to analyse this to determine common patterns in the code. Since the source code, before it is compiled to bytecode, is not deployed to the blockchain it is not possible to retrieve ...


3

you can use smartcontract.com to use any API (JSON) as the source of an oracle, so from there you can use it in any smart contract on ethereum network. https://smartcontract.com/


2

So this really depends on the contract, if the contract implemented a public method or a public state variable then it's possible for you to get the data. contract SimpleFetch { uint public fixedData = 12345; function get() public constant returns (uint) { return 12345; } function balanceOf(address _owner) constant returns (uint ...


1

It is server-based and topologically similar to a caching strategy. A purist might disagree, but an argument can be made that it is perfectly fine to use any sort of caching strategy (e.g. etherscan) subject to a few conditions. Users should be able to verify results independently, if they want to. This implies transparency. The cache should emit ...


1

It would help if you told us a bit more about what you're trying to achieve - why is your data split between the blockchain and your database? (I'm not saying this is the wrong thing to do, but the appropriate design will depend on your goals.) As you're describing it you're going to end up with two different actions, one putting the data in the database ...


1

I think the OP means complete to the currently accepted last node that was mined a little while ago. One way would be to build your own explorer - run a geth node - attach a console and use the web3 JavaScript library (https://github.com/ethereum/wiki/wiki/JavaScript-API) - get each block using getBlock - get each transaction and find the from and to ...


1

On the Ethereum Project under "Standardized Contract APIs", a small standard for feeds is defined. I do not know if it is the most widely used standard, though. This standard defines two required methods: set(bytes32 _key, <t> _value) and get(bytes32 _key) returns (<t> _r) where <t> should be replaced the data type in question (e.g. ...


1

The idea is that instead of you personally setting the price, there would be one centralized price feed that your contract queries every time it needs to know the price. These largely don't exist, but can be implemented pretty simply. The link is to a proposed standard for data-feed contracts so that you could add and remove feeds from various sources ...


1

Not sure about your specific use case, but have a look at http://microtick.com. The goal is to have a trustless data feed for Ethereum (for continuous data, i.e. free running - not a prediction market)


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