talfco/clb-kyber-java-tutorial

Repository used for Kyber Network tutorials

clb-kyber-java-tutorial

Repository used for the Kyber Network tutorial, which will be delivered as part of the following KyberDAO proposal:

• DaoStack Ethereum Contract Proposal: https://alchemy.daostack.io/dao/0x6bee9b81e434f7afce72a43a4016719315069539/proposal/0x25ea4cdb14c844bcf44691e588305b2d157fae0d696c5a7440c360691243c955

Progress Report: Expected Delivery 31.07.2019

• 01.07.2019: Initial kick off blog article: https://dev.cloudburo.net/2019/07/01/dao-project-work-announcement-kyberdao-proposal.html
• 15.07.2019: Integration approach into web3j library completed and implemented two api methods currencies and buyRate
• 24.07.2019: All three scenarios, eth2token, token2eth and token2token implemented, outstanding is the Medium Article
• 31.07.2019: All work completed

Introduction

The aim of this tutorial is to showcase an initial implementation of a Kyber Java Client API.

As an implementation strategy an enhancement of the well-known web3j library was chosen.

web3j is a highly modular, reactive, type safe Java and Android library for working with Smart Contracts and integrating with clients (nodes) on the Ethereum network.

Example Scenario: Perform ETH -> KNC (ERC20 token) conversion

The scenario consists of the following step

• check for the tokens supported on the Kyber Network, in our case the KNC token

• get the KNC/ETH buy rates

• get the trade data record

• sign and execute the transactions

    private void eth2knc() {
        Kyber3j kyber3j = Kyber3j.build(new KyberService(KyberService.KYBER_ROPSTEN));
        log.info("Connected to Kyber Network: "+KyberService.KYBER_ROPSTEN);
        // Buy KNC from ETH
        try {
            // Check if token is supported
            Currencies currencies = kyber3j.currencies().send();
            log.info("Exists Currency KNC: " + currencies.existsCurreny("KNC"));
            if (!checkForError(currencies) && currencies.existsCurreny("KNC")) {
                // Get buy rates
                BuyRate buyRate = kyber3j.buyRate(currencies.getCurrency("KNC").getId(),"1",
                        false).send();
                if (!checkForError(buyRate)) {
                    Rates rates = buyRate.getData().get(0);
                    SingleRate singleRate = rates.getSingleRate(0);
                    log.info("Conversion Rates: " + singleRate.getSrc_qty());
                    // Get tradeData
                    // Adjust conversion rates to 97%
                    singleRate.approximateReceivableToken(0.97);
                    TradeData tradeData = kyber3j.tradeData(credentials.getAddress(), singleRate, GasPriceRange.medium).send();
                    if (!checkForError(tradeData)) {
                        TradeData.TradeDataRecord rec = tradeData.getData().get(0);
                        RawTransaction rawTransaction = RawTransaction.createTransaction(
                                rec.getNonceAsBI(),  rec.getGasPriceAsBI(), rec.getGasLimitAsBI(),
                                rec.getTo(), rec.getValueAsBI(), rec.getData());
                        byte[] signedMessage = TransactionEncoder.signMessage(rawTransaction, credentials);
                        String hexValue = Numeric.toHexString(signedMessage);
                        log.info("Signe Message with Hex Value: "+hexValue);
                        //EthSendTransaction ethTrx = web3j.ethSendRawTransaction(hexValue).send();
                        EthSendTransaction ethSendTransaction = web3j.ethSendRawTransaction(hexValue).sendAsync().get();
                        log.info("Executed transaction "+ethSendTransaction.getTransactionHash());
                        // poll for transaction response via org.web3j.protocol.Web3j.ethGetTransactionReceipt(<txHash>)
                        return;
                    }
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }