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Smart Contract Execution

TxTypeSmartContractExecution executes a smart contract with the given data. TxTypeSmartContractExecution is accepted only if "to" is a smart contract account.

Import necessary classes from the Web3j and kaia libraries(web3j-ext).

Connect to the kaia blockchain using Web3j and specify the URL

Creating sender and fee payer credentials using private keys.

Define gas price and gas limit for the transaction

Get the sender's address from credentials.getAddress()

Getting the nonce for the sender's address

Define smart contract data

Get the chain ID from the Kaia network

Initialize variables for transaction parameters

Create a raw transaction

Signing the transaction as sender using KlayTransactionEncoder.signMessage.

Signing the transaction as fee payer using KlayTransactionEncoder.signMessageAsFeePayer.

Sending the signed transaction to kaia network

Getting the transaction receipt

Shutting down the Web3j instance

Decoding the raw transaction to get the transaction type

FeeDelegatedSmartContractExecutionExample.java

package org.web3j.example.transactions;

import org.web3j.tx.response.PollingTransactionReceiptProcessor;

import org.web3j.tx.response.TransactionReceiptProcessor;

import org.web3j.example.keySample;

import java.io.IOException;

import java.math.BigInteger;

import org.web3j.crypto.KlayCredentials;

import org.web3j.crypto.KlayRawTransaction;

import org.web3j.crypto.KlayTransactionEncoder;

import org.web3j.crypto.transaction.type.TxType;

import org.web3j.crypto.transaction.type.TxTypeFeeDelegatedSmartContractExecution;

import org.web3j.crypto.transaction.type.TxType.Type;

import org.web3j.protocol.core.DefaultBlockParameterName;

import org.web3j.protocol.core.methods.response.EthChainId;

import org.web3j.protocol.core.methods.response.EthSendTransaction;

import org.web3j.protocol.http.HttpService;

import org.web3j.protocol.kaia.Web3j;

import org.web3j.utils.Numeric;

import org.web3j.protocol.kaia.core.method.response.TransactionReceipt;

/**

*

*/

public class FeeDelegatedSmartContractExecutionExample implements keySample {

/**

*

*/

public static void run() throws Exception {

Web3j web3j = Web3j.build(new HttpService(keySample.BAOBAB_URL));

KlayCredentials credentials = KlayCredentials.create(keySample.LEGACY_KEY_privkey);

KlayCredentials credentials_feepayer = KlayCredentials.create(keySample.LEGACY_KEY_FEEPAYER_privkey);

BigInteger GAS_PRICE = BigInteger.valueOf(50000000000L);

BigInteger GAS_LIMIT = BigInteger.valueOf(6721950);

String from = credentials.getAddress();

BigInteger nonce = web3j.ethGetTransactionCount(from, DefaultBlockParameterName.LATEST).send()

.getTransactionCount();

String data = "0xcfae3217";

EthChainId EthchainId = web3j.ethChainId().send();

long chainId = EthchainId.getChainId().longValue();

String to = "0xc58294ecde8fdb288fd845e7a43a56564b597bdb";

byte[] payload = Numeric.hexStringToByteArray(data);

BigInteger value = BigInteger.ZERO;

TxType.Type type = Type.FEE_DELEGATED_SMART_CONTRACT_EXECUTION;

KlayRawTransaction raw = KlayRawTransaction.createTransaction(

type,

nonce,

GAS_PRICE,

GAS_LIMIT,

to,

value,

from,

payload);

// Sign as sender

byte[] signedMessage = KlayTransactionEncoder.signMessage(raw, chainId, credentials);

// Sign same message as Fee payer

signedMessage = KlayTransactionEncoder.signMessageAsFeePayer(raw, chainId, credentials_feepayer);

String hexValue = Numeric.toHexString(signedMessage);

EthSendTransaction transactionResponse = web3j.ethSendRawTransaction(hexValue).send();

System.out.println("TxHash : \n " + transactionResponse.getResult());

String txHash = transactionResponse.getResult();

int DEFAULT_POLLING_ATTEMPTS_PER_TX_HASH = 40;

int DEFAULT_BLOCK_TIME = 1 * 1000;

long DEFAULT_POLLING_FREQUENCY = DEFAULT_BLOCK_TIME;

TransactionReceiptProcessor transactionReceiptProcessor = new PollingTransactionReceiptProcessor(web3j,

DEFAULT_POLLING_FREQUENCY, DEFAULT_POLLING_ATTEMPTS_PER_TX_HASH);

org.web3j.protocol.core.methods.response.TransactionReceipt ethReceipt = transactionReceiptProcessor

.waitForTransactionReceipt(txHash);

System.out.println("Receipt from eth_getTransactionReceipt : \n" + ethReceipt);

TransactionReceipt receipt = web3j.klayGetTransactionReceipt(txHash).send().getResult();

System.out.println("Receipt from klay_getTransactionReceipt : \n" + receipt);

web3j.shutdown();

TxTypeFeeDelegatedSmartContractExecution rawTransaction = TxTypeFeeDelegatedSmartContractExecution

.decodeFromRawTransaction(signedMessage);

System.out.println("TxType : " + rawTransaction.getKlayType());

}

}

output

❯ java FeeDelegatedSmartContractExecutionExample.java

TxHash :

0x43419d6dd268fd246f82f69174b46e4b599e030feca5de4542a1b524559c0879

receipt :

class TransactionReceipt {

blockHash: 0x33376f94093970fcf54d9c87669a04046b245c59c68431afef3b3444ceada0d3

blockNumber: 0x8def1f0

codeFormat: null

contractAddress: null

feePayer: 0xcb0eb737dfda52756495a5e08a9b37aab3b271da

feePayerSignatures: [class TransactionReceiptFeePayerSignaturesInner {

V: 0x7f5

R: 0x934223d90aa3ca87b17ad1b8b9914512a58e54e337bdd28e746321b35da43b91

S: 0x2cf45437c26f6a849c142d69e5382ce142d8c1bf3115203d482e8d22eb83c164

}]

feeRatio: null

from: 0xa2a8854b1802d8cd5de631e690817c253d6a9153

gas: 0x66919e

effectiveGasPrice: 0x5d21dba00

gasPrice: 0xba43b7400

gasUsed: 0x86f3

humanReadable: null

key: null

input: 0xcfae3217

logs: []

logsBloom: 0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

nonce: 0x3cb

senderTxHash: 0x7c67092dcae6ba99682d0cac6ece60388099c198c0481c3f1cc03a6294303b61

signature: []

status: 0x1

txError: null

to: 0xc58294ecde8fdb288fd845e7a43a56564b597bdb

transactionHash: 0x43419d6dd268fd246f82f69174b46e4b599e030feca5de4542a1b524559c0879

transactionIndex: 0x0

type: TxTypeFeeDelegatedSmartContractExecution

typeInt: 49

value: 0x0

}

TxType : FEE_DELEGATED_SMART_CONTRACT_EXECUTION