### Execute Read method calldata For the execution of the ```calldata``` of the Read method, we use ...

2024-04-16T05:12:05Z

### Execute Read method calldata

For the execution of the ```calldata``` of the Read method, we use the previously learned RPC method: ```eth_call``` to execute it. We explained the ```eth_call``` RPC method of the Ethereum only did a demonstration of the ```Write``` method of the smart contract, in this section, we use the ```calldata``` method to demonstrate the execution of the smart contract Read method call. Let's use the ```balanceOf``` method of the WETH contract to read the current balance of WETH tokens in the wallet.

We use the debugging tool to test on the Ethereum mainnet at:

```javascript
function toAmount(s, decimals) {
return Number((BigDecimal(BigInt(s)) / BigDecimal(Math.pow(10, decimals))).toString())
}
function main() {
// ABI for WETH contracts
var abiWETH = `[{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"guy","type":"address"},{"name":"wad","type":"uint256"}],"name":"approve","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"src","type":"address"},{"name":"dst","type":"address"},{"name":"wad","type":"uint256"}],"name":"transferFrom","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"wad","type":"uint256"}],"name":"withdraw","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"decimals","outputs":[{"name":"","type":"uint8"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"","type":"address"}],"name":"balanceOf","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"dst","type":"address"},{"name":"wad","type":"uint256"}],"name":"transfer","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[],"name":"deposit","outputs":[],"payable":true,"stateMutability":"payable","type":"function"},{"constant":true,"inputs":[{"name":"","type":"address"},{"name":"","type":"address"}],"name":"allowance","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"payable":true,"stateMutability":"payable","type":"fallback"},{"anonymous":false,"inputs":[{"indexed":true,"name":"src","type":"address"},{"indexed":true,"name":"guy","type":"address"},{"indexed":false,"name":"wad","type":"uint256"}],"name":"Approval","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"src","type":"address"},{"indexed":true,"name":"dst","type":"address"},{"indexed":false,"name":"wad","type":"uint256"}],"name":"Transfer","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"dst","type":"address"},{"indexed":false,"name":"wad","type":"uint256"}],"name":"Deposit","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"src","type":"address"},{"indexed":false,"name":"wad","type":"uint256"}],"name":"Withdrawal","type":"event"}]`

// WETH contract address
var wethAddress = "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2"

// Register ABI for WETH contracts
exchange.IO("abi", wethAddress, abiWETH)

// The wallet address of the currently configured exchange object
var walletAddress = exchange.IO("address")

// Coded WETH contract's deposit method call
var calldataForDeposit = exchange.IO("encode", wethAddress, "balanceOf(address)", walletAddress)
Log("calldataForDeposit:", "0x" + calldataForDeposit)

// Construct the transaction as the first parameter of eth_call
var transaction = {
"from" : walletAddress,
"to" : wethAddress,
"data" : "0x" + calldataForDeposit,
}

// The second parameter of eth_call
var blockNumber = "latest"

// Call with eth_call
var ret = exchange.IO("api", "eth", "eth_call", transaction, blockNumber)
var wethBalance = exchange.IO("decode", "uint256", ret) // You can use exchange.IO("decode", ...) function to decode
Log("wethBalance:", toAmount(wethBalance, 18)) // Converted from wei to WETH units
}
```

Run in the debugging tool:

```run
2023-06-15 11:51:31 Info wethBalance: 0.015
2023-06-15 11:51:31 Info calldataForDeposit: 0x70a082310000000000000000000000006b3f11d807809b0b1e5e3243df04a280d9f94bf4
```

If the method of a smart contract has a return value, you can use the ```exchange.IO("decode", ...)``` function to decode it. You can see that the passing ```calldata``` method is the same as calling the smart contract's ```balanceOf``` method directly, getting the WETH balance of 0.015 WETH for my test wallet.

### Execute Write method calldata

For the execution of the Write method calldata, it is necessary to use the RPC method: ```eth_sendRawTransaction```.

Let's use the debugging tool and test it on the Ethereum mainnet at:

```javascript
function toAmount(s, decimals) {
return Number((BigDecimal(BigInt(s)) / BigDecimal(Math.pow(10, decimals))).toString())
}
function toInnerAmount(s, decimals) {
return (BigDecimal(s)*BigDecimal(Math.pow(10, decimals))).toFixed(0)
}
function main() {
// ABI for WETH contracts
var abiWETH = `[{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"guy","type":"address"},{"name":"wad","type":"uint256"}],"name":"approve","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"src","type":"address"},{"name":"dst","type":"address"},{"name":"wad","type":"uint256"}],"name":"transferFrom","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"wad","type":"uint256"}],"name":"withdraw","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"decimals","outputs":[{"name":"","type":"uint8"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"","type":"address"}],"name":"balanceOf","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"dst","type":"address"},{"name":"wad","type":"uint256"}],"name":"transfer","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[],"name":"deposit","outputs":[],"payable":true,"stateMutability":"payable","type":"function"},{"constant":true,"inputs":[{"name":"","type":"address"},{"name":"","type":"address"}],"name":"allowance","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"payable":true,"stateMutability":"payable","type":"fallback"},{"anonymous":false,"inputs":[{"indexed":true,"name":"src","type":"address"},{"indexed":true,"name":"guy","type":"address"},{"indexed":false,"name":"wad","type":"uint256"}],"name":"Approval","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"src","type":"address"},{"indexed":true,"name":"dst","type":"address"},{"indexed":false,"name":"wad","type":"uint256"}],"name":"Transfer","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"dst","type":"address"},{"indexed":false,"name":"wad","type":"uint256"}],"name":"Deposit","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"src","type":"address"},{"indexed":false,"name":"wad","type":"uint256"}],"name":"Withdrawal","type":"event"}]`

// WETH contract address
var wethAddress = "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2"

// Register ABI for WETH contract
exchange.IO("abi", wethAddress, abiWETH)

// The wallet address of the currently configured exchange object
var walletAddress = exchange.IO("address")

// Coded WETH contract's deposit method call
var calldataForDeposit = exchange.IO("encode", wethAddress, "deposit")
Log("calldataForDeposit:", "0x" + calldataForDeposit)

// Get nonce
var nonce = exchange.IO("api", "eth", "eth_getTransactionCount", walletAddress, "pending")

// Get gasPrice
var gasPrice = exchange.IO("api", "eth", "eth_gasPrice")

// Call the deposit method to change ETH to WETH, you need to transfer ETH, here we convert 0.01ETH to a hexadecimal value in wei
var innerAmount = BigInt(Number(toInnerAmount(0.005, 18))).toString(16)

// The transaction call object:
var obj = {
"from" : walletAddress,
"to" : wethAddress,
"gasPrice" : gasPrice,
"value" : "0x" + innerAmount,
"data" : "0x" + calldataForDeposit,
}

// Calculate gasLimit
var gasLimit = exchange.IO("api", "eth", "eth_estimateGas", obj)

// Construct a transaction
var transaction = {
"to": wethAddress,
"value": toAmount("0x" + innerAmount, 0), // Convert to decimal
"data": "0x" + calldataForDeposit,
"gasLimit": toAmount(gasLimit, 0), // Convert to decimal
"gasPrice": toAmount(gasPrice, 0), // Convert to decimal
"nonce": toAmount(nonce, 0), // Convert to decimal
"chainId": 1, // Ethereum mainnet Id
}
Log("transaction:", transaction)

// Signature, your key is replaced with your private key
var signedTx = Encode("signTx", "string", "hex", JSON.stringify(transaction), "hex", "0x" + "your key")
Log("signedTx:", "0x" + signedTx)

// Call eth_sendRawTransaction to send a transaction
var ret = exchange.IO("api", "eth", "eth_sendRawTransaction", "0x" + signedTx)
return ret
}
```

Run in the debugging tool:

```run
2023-06-15 09:58:50 Info signedTx: 0xf86f4f8504202067888...
2023-06-15 09:58:50 Info transaction: {"to":"0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2","value":5000000000000000,"data":"0xd0e30db0","gasLimit":27938,"gasPrice":17718863752,"nonce":79,"chainId":1}
2023-06-15 09:58:50 Info calldataForDeposit: 0xd0e30db0
```

Execute ```var ret = exchange.IO("api", "eth", "eth_sendRawTransaction", "0x" + signedTx)``` function and the returned Transaction Hash is: ``` 0x2ff585504b0fe59b0122f696e8808abfe2f3ce263448066533f3bb8a4f55e8e6```. The ```eth_sendRawTransaction``` call executes the calldata in it, calling the ```deposit``` method of the WETH contract to swap the 0.005 ETH sent for WETH.

## Listening to mempool

Before a user's transaction is packaged into the Ethereum blockchain by miners, all transactions will be pooled in ```Mempool``` (transaction memory pool), where "miners" also look for transactions with high fees to be packaged first, in order to maximize mining benefits. Therefore, usually the higher the transaction's gasPrice setting, the more likely it is to be packaged.

Some transaction scripts will also sniff ```Mempool``` in the hope of finding some profitable transactions. For example, if a transaction is set with a high exchange slippage, the transaction could be subject to a "sandwich attack'' by these transactionscripts. So how do these scripts listen for ```pending``` (pending, to-be-packaged) transactions in ```Mempool```?

### Listening with the REST protocol

Use the RPC method we learned before: ```eth_getBlockByNumber```, but we do not pass the specific ```blockNumber``` this time, we use the ```"pending"``` tag.

```javascript
function main() {
var data = exchange.IO("api", "eth", "eth_getBlockByNumber", "pending", true)
if (Array.isArray(data.transactions)) {
for (var i = 0; i < data.transactions.length; i++) {
Log(data.transactions[i])
}
}
}
```

Run in the debugging tool:

```run
2023-06-18 19:23:05 Info {"blockNumber":"0x10b2027","type":"0x2","accessList":[],"blockHash":"0xf833ed36435c53d63bd7109bb1e85383075534410c14573881bf26d912f46a89","from":"0xd50521974d62f1fa34b8e81cb742ccf6147d05ff","gasPrice":"0x32ea2db37","hash":"0xf8f10f8f473c340b021298feb48d0affe529e8737a309c4cc1902e8989ef0914","input":"0xa22cb4650000000000000000000000001e0049783f008a0085193e00003d00cd54003c710000000000000000000000000000000000000000000000000000000000000001","v":"0x0","value":"0x0","maxFeePerGas":"0x48a413364","maxPriorityFeePerGas":"0x5f5e100","nonce":"0x8","r":"0x8c1cc36f43b02c9e9e454153588cc9d38757f1da69ec49d3cfdda74ab69e06a8","s":"0x2f3dd3e5ddf9e5d42c128a8e900026aca7568fa83c68cf332e1328066ee8d03a","transactionIndex":"0x3a","chainId":"0x1","gas":"0x1142d","to":"0x8c3c0274c33f263f0a55d129cfc8eaa3667a9e8b"}
2023-06-18 19:23:05 Info {"input":"0x646174613a2c7b2270223a226572632d3230222c226f70223a226d696e74222c227469636b223a2265746873222c226964223a223139323732222c22616d74223a2231303030227d","nonce":"0x1d","blockHash":"0xf833ed36435c53d63bd7109bb1e85383075534410c14573881bf26d912f46a89","from":"0xe7fa86855af674837cea1b58f88b5352543ca27b","gas":"0x81cc","gasPrice":"0x32ea2db37","to":"0xe7fa86855af674837cea1b58f88b5352543ca27b","chainId":"0x1","transactionIndex":"0x39","type":"0x2","value":"0x0","accessList":[],"blockNumber":"0x10b2027","hash":"0x55702f5d14736fc9d0c58fdac2d2052a602db171c46b5e1fa9ff6af5c277f9a2","maxFeePerGas":"0x48a413364","maxPriorityFeePerGas":"0x5f5e100","r":"0x5a703d389d23b51adf8ef0f55db8876e7392636797b68a4be6afe73e76d7e1f2","s":"0x4b4bb11257c4434a0acc2672357f8793476e4bfdf98bc30d2389ce335e7de64e","v":"0x1"}
2023-06-18 19:23:05 Info {"gas":"0x186a0","nonce":"0x46533","r":"0xfeea052a4ac2283ca058a657a806ba0916d8e7d52d2a577f150c40eb1dfbec65","s":"0x5bf0089a3c060ba787b67a205b44e1065a0d11d132b41737ab9adf0f55066811","transactionIndex":"0x38","value":"0x78f0975742c400","blockHash":"0xf833ed36435c53d63bd7109bb1e85383075534410c14573881bf26d912f46a89","chainId":"0x1","hash":"0x56bdf1b38e23db66e8d1c4014d1e9f690a9217d8a0232489210325fc69e25cf9","v":"0x25","input":"0x","type":"0x0","blockNumber":"0x10b2027","gasPrice":"0x4a817c800","from":"0x97b9d2102a9a65a26e1ee82d59e42d1b73b68689","to":"0xcb513e99c020e9d15a6eafef873fef5d9f078221"}
...
```

Extract one piece of the data:

```javascript
{
"blockNumber": "0x10b2027",
"type": "0x2",
"accessList": [],
"blockHash": "0xf833ed36435c53d63bd7109bb1e85383075534410c14573881bf26d912f46a89",
"from": "0xd50521974d62f1fa34b8e81cb742ccf6147d05ff",
"gasPrice": "0x32ea2db37",
"hash": "0xf8f10f8f473c340b021298feb48d0affe529e8737a309c4cc1902e8989ef0914",
"input": "0xa22cb4650000000000000000000000001e0049783f008a0085193e00003d00cd54003c710000000000000000000000000000000000000000000000000000000000000001",
"v": "0x0",
"value": "0x0",
"maxFeePerGas": "0x48a413364",
"maxPriorityFeePerGas": "0x5f5e100",
"nonce": "0x8",
"r": "0x8c1cc36f43b02c9e9e454153588cc9d38757f1da69ec49d3cfdda74ab69e06a8",
"s": "0x2f3dd3e5ddf9e5d42c128a8e900026aca7568fa83c68cf332e1328066ee8d03a",
"transactionIndex": "0x3a",
"chainId": "0x1",
"gas": "0x1142d",
"to": "0x8c3c0274c33f263f0a55d129cfc8eaa3667a9e8b"
}
```

### Listening with the WebSocket protocol

In the FMZ Quant Trading Platform, we use the ```Dial``` function to create ```WebSocket``` connections, you can check the ```FMZ API``` documentation to learn the ```Dial``` function.

The test code in this section runs in the Ethereum mainnet environment, and it is easier to use the FMZ Quant to test in live trading due to the use of WebSocket protocol communication. The Websocket protocol subscription messages are:

```javascript
{"jsonrpc": "2.0", "id": 1, "method": "eth_subscribe", "params": ["newPendingTransactions"]}
```

In addition to ```newPendingTransactions```, you can also subscribe to ```newHeads```, ```logs```.

Receiving data pushed by ```WebSocket``` connections:

```javascript
{
"jsonrpc": "2.0",
"method": "eth_subscription",
"params": {
"subscription": "0x2c5c087b4aa188e008f4747828ef4e61",
"result": "0x69c4251cecb814e17cfe7a5ee41742a616f9a4d1bbf245c49b186b1006fd14d3"
}
}
```

Then further query ```transaction``` according to which: ```"result": "0x69c4251cecb814e17cfe7a5ee41742a616f9a4d1bbf245c49b186b1006fd14d3"```. For a specific ```transaction```, we use the Ethereum RPC method ```eth_getTransactionByHash``` to query.

```javascript
var ws = null

function main () {
// {"jsonrpc": "2.0", "id": 1, "method": "eth_subscribe", "params": ["xxxxx"]} , "xxxxx" is the specific message to subscribe to
var payload = {"jsonrpc": "2.0", "id": 1, "method": "eth_subscribe", "params": ["newPendingTransactions"]}

// wss://mainnet.infura.io/ws/v3/xxxxx , "xxxxx" is your infura key
var infuraKey = "your key"

ws = Dial("wss://mainnet.infura.io/ws/v3/" + infuraKey + "|reconnect=true&payload=" + JSON.stringify(payload))
if (!ws) {
throw "websocket link infura failed!"
}

// eth_getTransactionByHash call count
var getTransactionCounter = 0

var beginTS = new Date().getTime()

// Loop to get messages
while (true) {
// Receive push messages
var data = ws.read()
if (data) {
var ts = new Date().getTime()

if (ts - beginTS >= 1000) {
getTransactionCounter = 0
beginTS = ts
}

// Check transaction details based on txHash
if (ts - beginTS < 1000 && getTransactionCounter >= 100) {
Sleep(1000)
getTransactionCounter = 0
beginTS = ts
}

var obj = JSON.parse(data)
if (obj["params"] && obj["params"]["result"]) {
var transcationInfo = exchange.IO("api", "eth", "eth_getTransactionByHash", obj["params"]["result"])
Log(obj["params"]["result"], "transcationInfo:", transcationInfo)
}

getTransactionCounter++
}

LogStatus(_D())
}
}

function onexit() {
Log("Disconnect WS connection")
ws.close()
}
```

Create a live trading to run the above code, you can receive the data pushed by the WebSocket connection, the data is pushed constantly, we extract one of them - ```transaction```:

```javascript
{
"maxPriorityFeePerGas": "0x5f5e100",
"nonce": "0x1a9",
"accessList": [],
"blockNumber": "0x10b1c9f",
"from": "0x5888700be02f52c8adf85890886ef84a6b8a7829",
"blockHash": "0x92c3d77ea218cdc0967ab74b6005bb393b92355047f206c7e2d59d41828e7fa9",
"chainId": "0x1",
"gasPrice": "0x34fdbf43d",
"s": "0x7d86ae29a786a61b9e74a7a9e2cc4b39b7913aa3d4c3816ccb07528fed82048a",
"to": "0xfc2068c3d47b575a60f6a4a7bf60dea0ac368e01",
"type": "0x2",
"v": "0x1",
"value": "0x0",
"gas": "0x1aad3",
"hash": "0x2c77c0704aefbb26db460cbb71efdb488df968ad53d2c2b3f1e1172056b40b22",
"input": "0x42842e0e0000000000000000000000005888700be02f52c8adf85890886ef84a6b8a7829000000000000000000000000d2d07e4d1bb0f40ac3e4aa7cc3ad05d348bfd2c3000000000000000000000000000000000000000000000000000000000000180b",
"maxFeePerGas": "0x4712d1273",
"r": "0x8ec58f95f6d9729a6eee075e6976658b6c5346cbc90eb68ac361a40af073b10e",
"transactionIndex": "0xc1"
}
```

Excerpted (partial omission) log data:

```run
2023-06-18 16:20:07 Info Disconnect WS connection
2023-06-18 16:20:07 Info 0xba07ca903f9eafbfa7d494bb26197713034b9ca2dd3c19bc0898af3f35b59343 transcationInfo: {"accessList":[],"from":"0xe2977d60182da068dfd78693f96362ee7a2e9644","nonce":"0xf","value":"0x0","blockHash":"0x92c3d77ea218cdc0967ab74b6005bb393b92355047f206c7e2d59d41828e7fa9","blockNumber":"0x10b1c9f","chainId":"0x1","hash":"0xba07ca903f9eafbfa7d494bb26197713034b9ca2dd3c19bc0898af3f35b59343","maxFeePerGas":"0x530c30b70","r":"0xf28bfdf372a5401a2e00675c6ebe8d5e73f2c955db44b1aa56240b9197d6cbc7","type":"0x2","v":"0x0","gas":"0x21079","gasPrice":"0x367b3783d","input":"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","maxPriorityFeePerGas":"0x1dcd6500","s":"0x71d51246bb60e792f963a3c75c46fd8f557921ce6face7224c944e1768a76ca","to":"0x0b51eb9d0e54c562fedc07ceba453f05b70c4b79","transactionIndex":"0x40"}
2023-06-18 16:20:07 Info 0x2c77c0704aefbb26db460cbb71efdb488df968ad53d2c2b3f1e1172056b40b22 transcationInfo: {"maxPriorityFeePerGas":"0x5f5e100","nonce":"0x1a9","accessList":[],"blockNumber":"0x10b1c9f","from":"0x5888700be02f52c8adf85890886ef84a6b8a7829","blockHash":"0x92c3d77ea218cdc0967ab74b6005bb393b92355047f206c7e2d59d41828e7fa9","chainId":"0x1","gasPrice":"0x34fdbf43d","s":"0x7d86ae29a786a61b9e74a7a9e2cc4b39b7913aa3d4c3816ccb07528fed82048a","to":"0xfc2068c3d47b575a60f6a4a7bf60dea0ac368e01","type":"0x2","v":"0x1","value":"0x0","gas":"0x1aad3","hash":"0x2c77c0704aefbb26db460cbb71efdb488df968ad53d2c2b3f1e1172056b40b22","input":"0x42842e0e0000000000000000000000005888700be02f52c8adf85890886ef84a6b8a7829000000000000000000000000d2d07e4d1bb0f40ac3e4aa7cc3ad05d348bfd2c3000000000000000000000000000000000000000000000000000000000000180b","maxFeePerGas":"0x4712d1273","r":"0x8ec58f95f6d9729a6eee075e6976658b6c5346cbc90eb68ac361a40af073b10e","transactionIndex":"0xc1"}
2023-06-18 16:20:07 Info 0xbc42d5db10e5cb2e888c76005c522cb2474a0c0a7325feb867b618f69ff26f2a transcationInfo: {"accessList":[],"blockNumber":"0x10b1c9f","gas":"0x1cc12b","hash":"0xbc42d5db10e5cb2e888c76005c522cb2474a0c0a7325feb867b618f69ff26f2a","maxFeePerGas":"0x6ab262e5c","value":"0x0","v":"0x1","chainId":"0x1","from":"0xc1b634853cb333d3ad8663715b08f41a3aec47cc","input":"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
2023-06-18 16:20:06 Info 0xff0945c3d682a37e18ee433d56c8bedbb93d9ac368af968ed8d53b655575e8e5 transcationInfo: {"gas":"0x5208","s":"0x63572e1fa060841b939cea0849154e55781fe0efcbdfe5ce6979b44ce0980e4a","transactionIndex":"0xa7","value":"0x113e9d515e400","blockHash":"0x92c3d77ea218cdc0967ab74b6005bb393b92355047f206c7e2d59d41828e7fa9","hash":"0xff0945c3d682a37e18ee433d56c8bedbb93d9ac368af968ed8d53b655575e8e5","nonce":"0x2","r":"0x698fe26331ad39ba89c4d30985b707792ea4ab09b25205727f8fac2a6120b54a","gasPrice":"0x35458af00","from":"0x228d93af92d03184c07aa9e39b3d2d61b666686d","input":"0x","to":"0x0246177b98a5e42835cdcfaac1c274d3e6c39486","v":"0x26","blockNumber":"0x10b1c9f","type":"0x0","chainId":"0x1"}
...
```

## Decoding Transaction Details

In the previous course, we wrote a monitoring program to monitor pending transactions on Ethereum, get the pushed transaction hash via WebSocket protocol, and then query the specific transaction details based on the transaction hash.

Next we want to do further parsing of the ```input``` field data in the transaction details data. The ```input``` field data looks like a jumble of hexadecimal data, but it actually encodes the content of the transaction: including the functions called, and the parameters entered, etc.

After repeated and extensive testing, we found that the timeliness and quantity of data pushed over by the WebSocket connection has a lot to do with the RPC node currently in use, and the pushed data received by two different RPC node services (e.g., infura, ALCHEMY) when creating a WebSocket connection at the same time is not exactly the same, and since the current scenario generates a large number of requests, we still need to use a more stable and faster RPC service. The WebSocket connection also pushes a lot of transaction hashes that have been Pending for a long time, and when using ```eth_getTransactionByHash``` to query, you often get a null value (tested on FMZ, node.js).

We use the ```alchemy``` RPC node this time: ```wss://eth-mainnet.g.alchemy.com/v2/oKmOQKbneVkxgHZfibs-iFhIlIAl6HDN```. The node supports both WebSocket and REST protocols.

We monitor the ```multicall(uint256,bytes[])``` method of the router smart contract of the Uniswap decentralized exchange, so we need to calculate the function signature hash of the method first.

```
// Take the first 8 characters of the complete hash
// multicall: 0x5ae401dc
var sigHash = "0x" + Encode("keccak256", "string", "hex", "multicall(uint256,bytes[])").slice(0, 8)
```

Based on the example in the previous lesson, we have made some modifications. When receiving messages pushed by the WebSocket connection, the latest data is received using ```var data = ws.read(-2)``` method, and the ```read()``` function parameter is set to -2 to indicate that the latest data is returned immediately. We only care about the ```Transaction``` that contains the ```multicall``` call, using ```if (tx && tx.input.indexOf(sigHash) ! == -1)``` to determine the filter.

2 custom functions need to be designed:

- ```calcAllFuncSigHash()```: Calculate signature hash for all methods based on ABI.
- ```decodeCall()```: Decoding function.

Next, when the ```multicall``` call is detected, the decoding operation can start, and the parameters of the ```multicall``` method are decoded for the first time: ```deadline``` and ```data```. ```deadline``` is a timestamp that is better understood, and ```data``` is another encoded ```calldata```, so you still need to continue to use the ```decodeCall()``` function to decode it.

Example of a complete implementation:

```javascript
var ws = null
var arrLog = []

const ABI_Route = '[{"inputs":[{"internalType":"address","name":"_factoryV2","type":"address"},{"internalType":"address","name":"factoryV3","type":"address"},{"internalType":"address","name":"_positionManager","type":"address"},{"internalType":"address","name":"_WETH9","type":"address"}],"stateMutability":"nonpayable","type":"constructor"},{"inputs":[],"name":"WETH9","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"}],"name":"approveMax","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"}],"name":"approveMaxMinusOne","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"}],"name":"approveZeroThenMax","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"}],"name":"approveZeroThenMaxMinusOne","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"bytes","name":"data","type":"bytes"}],"name":"callPositionManager","outputs":[{"internalType":"bytes","name":"result","type":"bytes"}],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"bytes[]","name":"paths","type":"bytes[]"},{"internalType":"uint128[]","name":"amounts","type":"uint128[]"},{"internalType":"uint24","name":"maximumTickDivergence","type":"uint24"},{"internalType":"uint32","name":"secondsAgo","type":"uint32"}],"name":"checkOracleSlippage","outputs":[],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"bytes","name":"path","type":"bytes"},{"internalType":"uint24","name":"maximumTickDivergence","type":"uint24"},{"internalType":"uint32","name":"secondsAgo","type":"uint32"}],"name":"checkOracleSlippage","outputs":[],"stateMutability":"view","type":"function"},{"inputs":[{"components":[{"internalType":"bytes","name":"path","type":"bytes"},{"internalType":"address","name":"recipient","type":"address"},{"internalType":"uint256","name":"amountIn","type":"uint256"},{"internalType":"uint256","name":"amountOutMinimum","type":"uint256"}],"internalType":"struct IV3SwapRouter.ExactInputParams","name":"params","type":"tuple"}],"name":"exactInput","outputs":[{"internalType":"uint256","name":"amountOut","type":"uint256"}],"stateMutability":"payable","type":"function"},{"inputs":[{"components":[{"internalType":"address","name":"tokenIn","type":"address"},{"internalType":"address","name":"tokenOut","type":"address"},{"internalType":"uint24","name":"fee","type":"uint24"},{"internalType":"address","name":"recipient","type":"address"},{"internalType":"uint256","name":"amountIn","type":"uint256"},{"internalType":"uint256","name":"amountOutMinimum","type":"uint256"},{"internalType":"uint160","name":"sqrtPriceLimitX96","type":"uint160"}],"internalType":"struct IV3SwapRouter.ExactInputSingleParams","name":"params","type":"tuple"}],"name":"exactInputSingle","outputs":[{"internalType":"uint256","name":"amountOut","type":"uint256"}],"stateMutability":"payable","type":"function"},{"inputs":[{"components":[{"internalType":"bytes","name":"path","type":"bytes"},{"internalType":"address","name":"recipient","type":"address"},{"internalType":"uint256","name":"amountOut","type":"uint256"},{"internalType":"uint256","name":"amountInMaximum","type":"uint256"}],"internalType":"struct IV3SwapRouter.ExactOutputParams","name":"params","type":"tuple"}],"name":"exactOutput","outputs":[{"internalType":"uint256","name":"amountIn","type":"uint256"}],"stateMutability":"payable","type":"function"},{"inputs":[{"components":[{"internalType":"address","name":"tokenIn","type":"address"},{"internalType":"address","name":"tokenOut","type":"address"},{"internalType":"uint24","name":"fee","type":"uint24"},{"internalType":"address","name":"recipient","type":"address"},{"internalType":"uint256","name":"amountOut","type":"uint256"},{"internalType":"uint256","name":"amountInMaximum","type":"uint256"},{"internalType":"uint160","name":"sqrtPriceLimitX96","type":"uint160"}],"internalType":"struct IV3SwapRouter.ExactOutputSingleParams","name":"params","type":"tuple"}],"name":"exactOutputSingle","outputs":[{"internalType":"uint256","name":"amountIn","type":"uint256"}],"stateMutability":"payable","type":"function"},{"inputs":[],"name":"factory","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"factoryV2","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"},{"internalType":"uint256","name":"amount","type":"uint256"}],"name":"getApprovalType","outputs":[{"internalType":"enum IApproveAndCall.ApprovalType","name":"","type":"uint8"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"components":[{"internalType":"address","name":"token0","type":"address"},{"internalType":"address","name":"token1","type":"address"},{"internalType":"uint256","name":"tokenId","type":"uint256"},{"internalType":"uint256","name":"amount0Min","type":"uint256"},{"internalType":"uint256","name":"amount1Min","type":"uint256"}],"internalType":"struct IApproveAndCall.IncreaseLiquidityParams","name":"params","type":"tuple"}],"name":"increaseLiquidity","outputs":[{"internalType":"bytes","name":"result","type":"bytes"}],"stateMutability":"payable","type":"function"},{"inputs":[{"components":[{"internalType":"address","name":"token0","type":"address"},{"internalType":"address","name":"token1","type":"address"},{"internalType":"uint24","name":"fee","type":"uint24"},{"internalType":"int24","name":"tickLower","type":"int24"},{"internalType":"int24","name":"tickUpper","type":"int24"},{"internalType":"uint256","name":"amount0Min","type":"uint256"},{"internalType":"uint256","name":"amount1Min","type":"uint256"},{"internalType":"address","name":"recipient","type":"address"}],"internalType":"struct IApproveAndCall.MintParams","name":"params","type":"tuple"}],"name":"mint","outputs":[{"internalType":"bytes","name":"result","type":"bytes"}],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"bytes32","name":"previousBlockhash","type":"bytes32"},{"internalType":"bytes[]","name":"data","type":"bytes[]"}],"name":"multicall","outputs":[{"internalType":"bytes[]","name":"","type":"bytes[]"}],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"uint256","name":"deadline","type":"uint256"},{"internalType":"bytes[]","name":"data","type":"bytes[]"}],"name":"multicall","outputs":[{"internalType":"bytes[]","name":"","type":"bytes[]"}],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"bytes[]","name":"data","type":"bytes[]"}],"name":"multicall","outputs":[{"internalType":"bytes[]","name":"results","type":"bytes[]"}],"stateMutability":"payable","type":"function"},{"inputs":[],"name":"positionManager","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"},{"internalType":"uint256","name":"value","type":"uint256"}],"name":"pull","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[],"name":"refundETH","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"},{"internalType":"uint256","name":"value","type":"uint256"},{"internalType":"uint256","name":"deadline","type":"uint256"},{"internalType":"uint8","name":"v","type":"uint8"},{"internalType":"bytes32","name":"r","type":"bytes32"},{"internalType":"bytes32","name":"s","type":"bytes32"}],"name":"selfPermit","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"},{"internalType":"uint256","name":"nonce","type":"uint256"},{"internalType":"uint256","name":"expiry","type":"uint256"},{"internalType":"uint8","name":"v","type":"uint8"},{"internalType":"bytes32","name":"r","type":"bytes32"},{"internalType":"bytes32","name":"s","type":"bytes32"}],"name":"selfPermitAllowed","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"},{"internalType":"uint256","name":"nonce","type":"uint256"},{"internalType":"uint256","name":"expiry","type":"uint256"},{"internalType":"uint8","name":"v","type":"uint8"},{"internalType":"bytes32","name":"r","type":"bytes32"},{"internalType":"bytes32","name":"s","type":"bytes32"}],"name":"selfPermitAllowedIfNecessary","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"},{"internalType":"uint256","name":"value","type":"uint256"},{"internalType":"uint256","name":"deadline","type":"uint256"},{"internalType":"uint8","name":"v","type":"uint8"},{"internalType":"bytes32","name":"r","type":"bytes32"},{"internalType":"bytes32","name":"s","type":"bytes32"}],"name":"selfPermitIfNecessary","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountIn","type":"uint256"},{"internalType":"uint256","name":"amountOutMin","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"},{"internalType":"address","name":"to","type":"address"}],"name":"swapExactTokensForTokens","outputs":[{"internalType":"uint256","name":"amountOut","type":"uint256"}],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountOut","type":"uint256"},{"internalType":"uint256","name":"amountInMax","type":"uint256"},{"internalType":"address[]","name":"path","type":"address[]"},{"internalType":"address","name":"to","type":"address"}],"name":"swapTokensForExactTokens","outputs":[{"internalType":"uint256","name":"amountIn","type":"uint256"}],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"},{"internalType":"uint256","name":"amountMinimum","type":"uint256"},{"internalType":"address","name":"recipient","type":"address"}],"name":"sweepToken","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"},{"internalType":"uint256","name":"amountMinimum","type":"uint256"}],"name":"sweepToken","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"},{"internalType":"uint256","name":"amountMinimum","type":"uint256"},{"internalType":"uint256","name":"feeBips","type":"uint256"},{"internalType":"address","name":"feeRecipient","type":"address"}],"name":"sweepTokenWithFee","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"address","name":"token","type":"address"},{"internalType":"uint256","name":"amountMinimum","type":"uint256"},{"internalType":"address","name":"recipient","type":"address"},{"internalType":"uint256","name":"feeBips","type":"uint256"},{"internalType":"address","name":"feeRecipient","type":"address"}],"name":"sweepTokenWithFee","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"int256","name":"amount0Delta","type":"int256"},{"internalType":"int256","name":"amount1Delta","type":"int256"},{"internalType":"bytes","name":"_data","type":"bytes"}],"name":"uniswapV3SwapCallback","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountMinimum","type":"uint256"},{"internalType":"address","name":"recipient","type":"address"}],"name":"unwrapWETH9","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountMinimum","type":"uint256"}],"name":"unwrapWETH9","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountMinimum","type":"uint256"},{"internalType":"address","name":"recipient","type":"address"},{"internalType":"uint256","name":"feeBips","type":"uint256"},{"internalType":"address","name":"feeRecipient","type":"address"}],"name":"unwrapWETH9WithFee","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"uint256","name":"amountMinimum","type":"uint256"},{"internalType":"uint256","name":"feeBips","type":"uint256"},{"internalType":"address","name":"feeRecipient","type":"address"}],"name":"unwrapWETH9WithFee","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"uint256","name":"value","type":"uint256"}],"name":"wrapETH","outputs":[],"stateMutability":"payable","type":"function"},{"stateMutability":"payable","type":"receive"}]'

function calcAllFuncSigHash(jsonABI) {
var mapSigHash = {}
for (var i in jsonABI) {
var ele = jsonABI[i]
if (typeof(ele["name"]) != "undefined") {
if (ele["inputs"]) {
var funcName = ele["name"]
if (ele["inputs"].length == 0) {
var methodId = "0x" + Encode("keccak256", "string", "hex", funcName + "()").slice(0, 8)
mapSigHash[methodId] = {"argsTypeList": [], "argsNameList": [], "funcName": funcName}
} else {
var arr = []
var arrName = []
var argPrototype = []
for (var j in ele["inputs"]) {
var inputType = ele["inputs"][j]["type"]
if (inputType == "tuple") {
var components = ele["inputs"][j]["components"]
var tupleType = []
var protoType = []
for (var componentsIdx = 0; componentsIdx < components.length; componentsIdx++) {
tupleType.push(components[componentsIdx]["type"])
protoType.push(components[componentsIdx]["name"] + " " + components[componentsIdx]["type"])
}
arr.push("(" + tupleType.join() + ")")
arrName.push(ele["inputs"][j]["name"])
// Prototype
argPrototype.push("tuple" + "(" + protoType.join() + ")")
} else {
arr.push(inputType)
arrName.push(ele["inputs"][j]["name"])
// Prototype
argPrototype.push(inputType)
}
}
var functionSignature = funcName + "(" + arr.join() + ")"
var methodId = "0x" + Encode("keccak256", "string", "hex", functionSignature).slice(0, 8)
mapSigHash[methodId] = {"argsTypeList": arr, "argsNameList": arrName, "funcName": funcName, "argPrototype": argPrototype}
}
}
}
}
return mapSigHash
}

function decodeCall(input, abi) {
var mapSigHash = calcAllFuncSigHash(JSON.parse(abi))
var methodId = input.slice(0, 10)
var data = input.slice(10)

var decodedArgs = {}
var infoMethod = mapSigHash[methodId]
if (typeof(infoMethod) == "undefined") {
return [methodId, mapSigHash]
}

var arr = []
for (var i = 0; i < infoMethod["argsTypeList"].length; i++) {
if (infoMethod["argsTypeList"][i].startsWith("(")) {
arr.push(infoMethod["argPrototype"][i])
} else {
arr.push(infoMethod["argsTypeList"][i])
}
}

if (arr.length == 0) {
return {"funcName": infoMethod["funcName"], "args": decodedArgs}
}

var args = exchange.IO("decode", arr.join(), data)

if (!Array.isArray(args)) {
args = [args]
}

if (args.length != infoMethod["argsNameList"].length) {
Log("args:", args)
Log("infoMethod:", infoMethod)
throw "The decoded args are not equal to the argsNameList"
}

for (var i = 0; i < infoMethod["argsNameList"].length; i++) {
var key = infoMethod["argsNameList"][i]
var value = args[i]
decodedArgs[key] = value
}

return {"funcName": infoMethod["funcName"], "args": decodedArgs}
}

function main () {
// {"jsonrpc": "2.0", "id": 1, "method": "eth_subscribe", "params": ["xxxxx"]} , "xxxxx" is the specific message of the subscription
var payload = {"jsonrpc": "2.0", "id": 1, "method": "eth_subscribe", "params": ["newPendingTransactions"]}

// Use the alchemy service
ws = Dial("wss://eth-mainnet.g.alchemy.com/v2/oKmOQKbneVkxgHZfibs-iFhIlIAl6HDN" + "|reconnect=true&payload=" + JSON.stringify(payload))
if (!ws) {
throw "websocket link to alchemy failed!"
}

// eth_getTransactionByHash call count
var getTransactionCounter = 0

// Start Timestamp
var beginTS = new Date().getTime()

// Calculate function signature hash
var sigHash = "0x" + Encode("keccak256", "string", "hex", "multicall(uint256,bytes[])").slice(0, 8)
Log("sigHash:", sigHash)

// Loop for messages
while (true) {
var msg = ""
var recv = null
// Receive pushed messages, use the read parameter -2, and return the latest data immediately
var data = ws.read(-2)
if (data && data != "") {
var ts = new Date().getTime()

if (ts - beginTS >= 1000) {
getTransactionCounter = 0
beginTS = ts
}

// Check transaction details based on txHash
if (ts - beginTS < 1000 && getTransactionCounter >= 100) {
Sleep(1000)
getTransactionCounter = 0
beginTS = ts
}

var obj = JSON.parse(data)
if (obj["params"] && obj["params"]["result"]) {
var txHash = obj["params"]["result"]
var tx = exchange.IO("api", "eth", "eth_getTransactionByHash", txHash)

if (tx && tx.input.indexOf(sigHash) !== -1) {
// Decode transaction details
arrLog = []
var decodedInput = decodeCall(tx.input, ABI_Route)

// Log("----------------", txHash, "/", decodedInput["funcName"], "----------------", "#FF0000")
arrLog.push("----------------" + txHash + "/" + decodedInput["funcName"] + "----------------" + "#FF0000")
arrLog.push(tx.from + " -> " + tx.to)

for (var i = 0; i < decodedInput["args"]["data"].length; i++) {
var calldata = "0x" + decodedInput["args"]["data"][i]
var decodedCalldata = decodeCall(calldata, ABI_Route)

// Log("----------------", decodedCalldata["funcName"], "----------------", "#FF0000")
arrLog.push("----------------" + decodedCalldata["funcName"] + "----------------" + "#FF0000")

for (var key in decodedCalldata["args"]) {
// Log(key, decodedCalldata["args"][key])
arrLog.push(key + ": " + JSON.stringify(decodedCalldata["args"][key]))
}
}

// Output logs
for (var logIdx = arrLog.length - 1; logIdx >= 0; logIdx--) {
Log(arrLog[logIdx])
}
}

getTransactionCounter++
}
recv = obj
} else if (data == null) {
msg = "The buffer queue is empty, time:" + _D()
}

LogStatus(_D(), ", msg:", msg, ", recv:", recv)
}
}

function onexit() {
Log("Disconnect WS connection")
ws.close()
}

function onerror() {
Log("Disconnect WS connection")
ws.close()

for (var logIdx = arrLog.length - 1; logIdx >= 0; logIdx--) {
Log(arrLog[logIdx])
}
}
```

Create a live trading to test:

```run
2023-06-20 17:01:00 Info ----------------0x5288a7bd6e0f57162ca763df722de73793e542734d7d2b7af5755664e2e67910/multicall----------------
2023-06-20 17:01:00 Info 0x851b594033d57c98af753bcb3a7d0237a615de32 -> 0x68b3465833fb72a70ecdf485e0e4c7bd8665fc45
2023-06-20 17:01:00 Info ----------------exactInputSingle----------------
2023-06-20 17:01:00 Info params: {"tokenOut":"0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2","fee":"10000","recipient":"0x0000000000000000000000000000000000000002","amountIn":"8952087000296027130940868","amountOutMinimum":"41638694112306829","sqrtPriceLimitX96":"0","tokenIn":"0xe1283567345349942acdfad3692924a1b16cf3cc"}
2023-06-20 17:01:00 Info ----------------unwrapWETH9----------------
2023-06-20 17:01:00 Info amountMinimum: "41638694112306829"
2023-06-20 17:01:00 Info recipient: "0x851b594033d57c98af753bcb3a7d0237a615de32"
2023-06-20 16:59:03 Info ----------------0x55e0c4a38a17d3aa6e8f558a66c77e9defa9f8f6e347536363ac1b921de9aaf3/multicall----------------
2023-06-20 16:59:03 Info 0x27457ada2dd725c7d0f28e1737bdd0bf583c0f0b -> 0x68b3465833fb72a70ecdf485e0e4c7bd8665fc45
2023-06-20 16:59:03 Info ----------------swapExactTokensForTokens----------------
2023-06-20 16:59:03 Info amountIn: "816769666850161"
2023-06-20 16:59:03 Info amountOutMin: "40404501509302321"
2023-06-20 16:59:03 Info path: ["0x7863e06bca47ded821fcb53ab788eeb371243eda","0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2"]
2023-06-20 16:59:03 Info to: "0x27457ada2dd725c7d0f28e1737bdd0bf583c0f0b"
2023-06-20 16:58:25 Info sigHash: 0x5ae401dc
```

Screenshot:
https://stocksharp.com/file/150279
You can see that the Transaction Hash is ```0x5288a7bd6e0f57162ca763df722de73793e542734d7d2b7af5755664e2e67910``` for this transaction, and the input data data contains the call to a ```multicall``` method call. This transaction is sent in the direction: 0x851b594033d57c98af753bcb3a7d0237a615de32 -> 0x68b3465833fb72a70ecdf485e0e4c7bd8665fc45. ```0x68b3465833fb72a70ecdf485e0e4c7bd8665fc45 ``` is Uniswap's router contract address.
https://stocksharp.com/file/150280
The ```multicall``` package is parsed to call the contract's ```exactInputSingle``` and ```unwrapWETH9``` methods and the specific parameters of these methods.

```
----------------exactInputSingle----------------
params: {
"tokenOut":"0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2",
"fee":"10000",
"recipient":"0x0000000000000000000000000000000000000002",
"amountIn":"8952087000296027130940868",
"amountOutMinimum":"41638694112306829",
"sqrtPriceLimitX96":"0",
"tokenIn":"0xe1283567345349942acdfad3692924a1b16cf3cc"
}

----------------unwrapWETH9----------------
amountMinimum: "41638694112306829"
recipient: "0x851b594033d57c98af753bcb3a7d0237a615de32"
```

If you are interested, you can modify and extend the example based on it to monitor more transactions and parse these on-chain operations.
From: https://blog.mathquant.c...-ethereum-using-fmz.html

Get Started with web3 Development Easily Based on Ethereum Using FMZ (7)

### Execute Read method calldata For the execution of the ```calldata``` of the Read method, we use ...