provable/ethereum-api

Provable API for Ethereum smart contracts

Hassan Abdel-Rahman

@habdelra

@oraclize-support I'm continuing to see issues in Rinkeby with oraclize queries not being processed. Here is a query I just tried: oraclize issued me a query ID: 0x508819b632d5b43197ce0d2d50b3ad68893a8d4084757fa5b4514810c3ffc301 from the rinkeby txn hash: 0x64b41eee439569cc97dfae7043e9c92c683a23be863994a9a105ea7ad223e171. But when I check in the query status page, i see that the query is not found: https://app.provable.xyz/home/check_query?id=508819b632d5b43197ce0d2d50b3ad68893a8d4084757fa5b4514810c3ffc301

Oraclize Support

@oraclize-support

Hello @habdelra - thanks for your patience. At the moment, there are stability issues on Rinkeby that are affecting our service. We will reschedule your unprocessed queries and drop here another message when the outage is definitely over.

Coffee Converter

@coffee-converter

@oraclize-support are you guys able to use the ethereum-bridge on a truffle develop instance? I'm able to get it up and running I believe, but when calling provable_newRandomDSQuery(...) it reverts every time with no message.

Oraclize Support

@oraclize-support

@coffee-converter - yeah you can use the bridge with truffle. If you look at this repo here you can see a bunch of examples of using the bridge in a truffle develop environment: https://github.com/provable-things/ethereum-examples/tree/master/solidity/truffle-examples

Coffee Converter

@coffee-converter

ah ok..but it looks like the random datasource cant be used on a private chain, right? Only testnets?

Oraclize Support

@oraclize-support

@coffee-converter - correct, but if you're using one of the testnet you don't need the bridge, because our service is already deployed on the public testnets.

Coffee Converter

@coffee-converter

yep, ok thanks, I've got it working directly on the testnet. I guess I can disable my contract's random datasource calls when testing locally

3rr0rrs

@3rr0rrs

@oraclize-support
I've added new IPFS multihash to the contract, unfortunately after that the ethereum-bridge started to receive result "null" even for simple examples like print(777).
If I change multihash to the old one everything is working correct. I've reset Ganache, run new eth-bridge, did truffle networks --clean and truffle migrate, but still "null" result remains.

Do you have idea what may cause that?

Thanh-Quy Nguyen

@tnguyen42

Hi everyone, would anyone know if there's a way to only allow a Provable function to be called by Provable's servers or myself? Something similar to onlyOwner but... onlyProvable?

Oraclize Support

@oraclize-support

Hello @tnguyen42, this is what is normally done in the __callback method, for example here: https://github.com/provable-things/ethereum-examples/blob/052ce8186df4b907bf3cddd0858c19dc054ac320/solidity/KrakenPriceTicker.sol#L26

Thanh-Quy Nguyen

@tnguyen42

I missed an "only", sorry @oraclize-support ^^

I guess the __callback function is public, isn't it?

omg

I just got what you showed me

Thanks!

Thanh-Quy Nguyen

@tnguyen42

By the way @oraclize-support , is it normal that the documentation I have here https://docs.provable.xyz/#ethereum-quick-start isn't up to date? There's no mention of function's privacy, Solidity's version is still 0.4.22...

Is it not the latest documentation version?

Oraclize Support

@oraclize-support

@tnguyen42 that's the latest documentation, it should be easy to adapt it to the latest Solidity syntax changes: Solidity keeps changing and while we are keeping up with the compatibility, we don't continuously update all our educational material (including the docs). If you have any doubt please feel free to ask here, we would be happy to help!

ktimam

@ktimam

Hello

I'm trying to use provable random, and fees of 0.012 ethers are being paid to provable, equating to $1.6 as opposed to stated price of $0.05. Any thoughts on what i'm doing wrong? link to transaction:

https://ropsten.etherscan.io/tx/0x5c4c25fe1c2cb00fea48544ea1a6ab7ecec328b11831d9d2e06e404496693f6f

Oraclize Support

@oraclize-support

Hello @ktimam , if you could share the code (at least the portion where the query is called + the callback) we would have more info to see what's going on. My first guess is that you are setting a callback gas which is way too high: other than the query fee you are also covering the callback gas costs since Provable will need to supply these to your contract in order to be able to send you back the callback. What is the gas you have set for the callback?

ktimam

@ktimam

uint256 QUERY_EXECUTION_DELAY = 0;
uint256 GAS_FOR_CALLBACK = 600000;
bytes32 queryId = provable_newRandomDSQuery(QUERY_EXECUTION_DELAY, NUM_RANDOM_BYTES_REQUESTED, GAS_FOR_CALLBACK);

In the callback, i am calling another provable query (computation to add file to ipfs)

https://ropsten.etherscan.io/tx/0xead5d34a5e888fed9da83221d9fc254a1d62507ec33bf8bb9e4b5af06970967f

This is the callback (please note that the cost of ethers passed is slightly higher then the computation cost, 0.66 vs 0.5 which i'm guessing is due to adding gas fees)

In addition i'd like to know if provable is supported in one of the scalability solutions, like loom or matic, as the cost is currently too high to accommodate for a wide scale implementation?

Thanh-Quy Nguyen

@tnguyen42

@oraclize-support Thanks a lot!

Oraclize Support

@oraclize-support

Hi @ktimam - the slight discrepancies seen in the pricing may also be due to the price peg used on the testnets is not updated as it is on the mainnet, since the testnet ether is free. But yes, what you're seeing is that as usual, the overwhelming large part of the cost ( > 85% ) is due to gas fees rather than the base cost of the service.

As for matic of loom integrations - we have none specifically but if they follow the EVM format and work with web3 etc, the ethereum-bridge we provide for interacting with private chains will work for that integration out of the box. You can find more info here: https://github.com/provable-things/ethereum-bridge

Mayowa Tudonu

@mayorcoded

@oraclize-support Is your outage on Rinkeby over yet?

Oraclize Support

@oraclize-support

@mayorcoded - oh blimey we must have forgotten to post an update in here but yes, it's over and rinkeby has been working fine over the weekend. Sorry for the delay in letting you know!

Mayowa Tudonu

@mayorcoded

Alright, cool

Thank you.

ktimam

@ktimam

@oraclize-support thanks a lot for your support.

Oraclize Support

@oraclize-support

@ktimam - no worries, as ever let us know if you have any further issues!

Evgeni Pirianov

@BatiGencho

@oraclize-support We need to make the oracle return back to us a 1 or 2-dimensional array (gotten as an URL response) (e.g. [
[assetId, expiryTime, noOfDecimalPlaces, 0, 0, 0, ],
[strike1, 0, 0, 0, 0, 0, 0],
[traderAddress1_1, matcherAddress1_1, traderInvestement1_1, matcherInvestment1_1, isCall1_1, notional1_1],
[traderAddress1_2, matcherAddress1_2, traderInvestement1_2, matcherInvestment1_2, isCall1_2, notional1_2],
[strike2, 0, 0, 0, 0, 0, 0],
[traderAddress2_1, matcherAddress2_1, traderInvestement2_1, matcherInvestment2_1, isCall2_1, notional2_1],
....
]) . How can we do that ? What kind of query do we need ?

Oraclize Support

@oraclize-support

Hi @BatiGencho - all Provable queries will return to you a string, meaning that once you've found an endpoint that can serve you the data you want, you'll get it as a string. This means you'll have to follow up your query with some kind of parsing in order to create the array you need. There are various decent libraries out there for parsing strings in Solidity, such as this one: https://github.com/Arachnid/solidity-stringutils that'll help you convert your result to the type you need.

Evgeni Pirianov

@BatiGencho

@oraclize-support Since we are running on GCP and applying firewall rules to any incomming traffic, is there a certain IP range your oracle service would use to call our endpoint. If there is, can you share it with us so we can whitelist you. Thax a lot

Oraclize Support

@oraclize-support

@BatiGencho - there is no fixed IP I'm afraid so whitelisint isn't possible. One option is to use credenitals in your URL, and then use the encrypted queries we offer to keep those credentials secret in your smart contract.

Another option you have is to use the computation datasource to build a URL query with credentials so you can allow access that way if you like. You can see an example here: https://github.com/provable-things/ethereum-examples/tree/master/solidity/truffle-examples/url-requests

Thanh-Quy Nguyen

@tnguyen42

Hey @oraclize-support , can I have a contractChild is contractA, contractB { ... }, knowing that both contractA and contractB are usingProvable?

This is in order to create cron jobs with different frequencies ^^

Oraclize Support

@oraclize-support

@tnguyen42 - it compiled just fine when I tried it now ;) So yes, entirely possible.

Evgeni Pirianov

@BatiGencho

@oraclize-support One more question, is there a max. amount in terms of what the oracle could return as a string in the __callback ? That means what is the max. payload in byte size you would push baclk to the smart contract?

Oraclize Support

@oraclize-support

@BatiGencho - the hard limit you have here really is the block gas limit and the amount of gas required to handle the string depening on what you're doing with it in your __callback.

Thanh-Quy Nguyen

@tnguyen42

@oraclize-support Sounds promising, but isn't there a risk for conflicts? I don't really understand the Provable.sol since I didn't really spend enough time to try and understand it ^^

Oraclize Support

@oraclize-support

@tnguyen42 - no doubt there is, we've no experience with this particular setup and so would encourage you to make sure you test the behaviour you need fully

Thanh-Quy Nguyen

@tnguyen42

@oraclize-support Okay, thanks! I'll check it ^^

denisponizhan

@denisponizhan

@oraclize-support Hello. I have a strange issue - __callback haven't been called. https://kovan.etherscan.io/address/0x5231A73a8BED6a5a1EE27BB44aE35Ee906542060
It works all time, but today it doesn't work. Are you facing some difficulties in Kovan today? Why this happens?

Oraclize Support

@oraclize-support

@denisponizhan we are experiencing some issues, we'll get back when everything is recovered

denisponizhan

@denisponizhan

Thanks!

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