建設費委託示例
目錄
- 1. 導言
- 2. 如何進行收費授權
- 2.1 發送方簽署交易
- 2.2 付款人簽署交易
- 3. 收費委託的簡單服務器和客戶端
- 3.1 Environment setup
- 3.2 Sender's client
- 3.2 繳費者服務器
- 4. 運行示例
- 4.1 運行
feepayer_server.js
- 4.2 運行
sender_client.js
- 4.3 檢查
feepayer_server.js
- 4.4 View on Kaiascan
- 4.1 運行
1. 導言
This tutorial guides you through creating a simple server-client example using the Kaia SDK (ethers-ext) to demonstrate how fee-delegated value transfer transactions work on Kaia. The tutorial and example code are tested on the Kairos testnet.
2. 如何進行費用委託
讓我們簡要了解一下費用委託的運作方式。
2.1 發送方簽署交易
發送方 "在發送交易之前,應始終簽署交易。
To sign a transaction, use signTransaction which signs a transaction with given private key.
const senderAddress = "SENDER_ADDRESS";const senderPrivateKey ="SENDER_PRIVATE_KEY";const recieverAddr = "RECEIVER_ADDRESS";// Create a new transactionlet tx = { type: TxType.FeeDelegatedValueTransfer, to: recieverAddr, value: parseKaia("0.01"), from: senderAddress,}; // Sign the transactiontx = await senderWallet.populateTransaction(tx);console.log(tx);const senderTxHashRLP = await senderWallet.signTransaction(tx);console.log("senderTxHashRLP", senderTxHashRLP);
If there are no errors, then senderTxHashRLP
will have a signed transaction which is signed by the senderPrivateKey
.
Now, you need to send the senderTxHashRLP
to the fee payer. There are various ways to implement this. In this tutorial, we will provide you a simple server-client code as an example of sending a senderTxHashRLP
to the fee payer.
2.2 付款人簽署交易
When fee payer
receives the senderTxHashRLP
, fee payer
signs the senderTxHashRLP
again with their private key and sends the transaction to Kaia. 下面的代碼片段說明瞭這一過程。
sendTransactionAsFeePayer method signs the transaction with the given fee payer private key before sending the transaction. Before running the code, kindly replace "FEEPAYER_ADDRESS" and "PRIVATE_KEY" with the actual values.
Note that when the fee payer submits the transaction to Kaia on behalf of the sender, the senderTxHashRLP
type must be a FeeDelegatedValueTransfer
type of transaction.
const feePayerAddress = "FEEPAYER_ADDRESS";const feePayerPrivateKey = "FEEPAYER_PRIVATE_KEY"const sentTx = await feePayerWallet.sendTransactionAsFeePayer(senderTxHashRLP);console.log("sentTx", sentTx);const rc = await sentTx.wait();console.log("receipt", rc);.on('transactionHash', function(hash){ ...}).on('receipt', function(receipt){ ...}).on('error', console.error); // If an out-of-gas error, the second parameter is the receipt.
3. Simple server and client for fee delegation
Let's write a simple server and client using above fee delegation code.
3.1 Environment setup
We will use npm init -y
to setup our Node.js project, and install ethers-ext
mkdir feedelegation_servercd feedelegation_servernpm init -ynpm install - -save @kaiachain/ethers-ext@^1.2.0 ethers@6
@kaiachain/ethers-ext@^1.2.0 recommends node 22 or later
3.2 Sender's client
首先,我們要編寫一個sender_client.js
,如下所示。
In the example, kindly replace "SENDER_ADDRESS"
, "SENDER_PRIVATEKEY"
and "RECEIVER_ADDRESS"
with the actual values.
const { Socket } = require("net");const client = new Socket();const { Wallet, TxType, parseKaia } = require("@kaiachain/ethers-ext").v6;const ethers = require("ethers");const senderAddress = "SENDER_ADDRESS";const senderPrivateKey = "SENDER_PRIVATE_KEY";const recieverAddr = "RECEIVER_ADDRESS";const sendFeeDelegateTx = async () => { try { const provider = new ethers.JsonRpcProvider("https://public-en-kairos.node.kaia.io"); const senderWallet = new Wallet(senderPrivateKey, provider); // Create a new transaction let tx = { type: TxType.FeeDelegatedValueTransfer, to: recieverAddr, value: parseKaia("0.01"), from: senderAddress, }; // Sign the transaction tx = await senderWallet.populateTransaction(tx); console.log(tx); const senderTxHashRLP = await senderWallet.signTransaction(tx); console.log("senderTxHashRLP", senderTxHashRLP); if (!senderTxHashRLP) { throw new Error("Failed to generate raw transaction"); } // Send signed raw transaction to fee payer's server client.connect(1337, "127.0.0.1", () => { console.log("Connected to fee delegated service"); client.write(senderTxHashRLP); }); client.on("data", (data) => { console.log("Received data from server:", data.toString()); }); client.on("error", (error) => { console.error("Connection error:", error); s; }); client.on("close", () => { console.log("Connection closed"); }); } catch (error) { console.error("Transaction error:", error); client.end(); process.exit(1); } }; sendFeeDelegateTx();
The above code signs a fee delegated value transfer transaction with senderPrivateKey
and sends the signed senderTxHashRLP
to the fee payer's server which is running on port 1337
on 127.0.0.1
, i.e. localhost.
3.3 Fee payer's server
Now let's write the fee payer's server, feepayer_server.js
, which signs the received senderTxHashRLP
with feePayerPrivateKey
and sends it to Kairos testnet.
In the below example, kindly replace "FEEPAYER_ADDRESS"
and "FEEPAYER_PRIVATEKEY"
with actual values.
const { createServer } = require("net");const { Wallet, JsonRpcProvider } = require("@kaiachain/ethers-ext").v6;const feePayerAddress = "FEEPAYER_ADDRESS";const feePayerPrivateKey = "FEEPAYER_PRIVATE_KEY";const provider = new JsonRpcProvider("https://public-en-kairos.node.kaia.io");const feePayerWallet = new Wallet(feePayerPrivateKey, provider);const feePayerSign = async (senderTxHashRLP, socket) => { try { // Send the transaction const sentTx = await feePayerWallet.sendTransactionAsFeePayer(senderTxHashRLP); console.log("sentTx", sentTx); const rc = await sentTx.wait(); console.log("receipt", rc); if (rc.transactionHash) { socket.write(`Tx hash: ${rc.transactionHash}\n`); socket.write(`Sender Tx hash: ${rc.senderTxHash || ""}\n`); } } catch (error) { console.error("Error in feePayerSign:", error); socket.write(`Error: ${error.message}\n`); }};const server = createServer(function (socket) { console.log("Client is connected ..."); socket.write("This is fee delegating service"); socket.write("Fee payer is " + feePayerAddress); socket.on("data", function (data) { console.log("Received data from client:", data.toString()); feePayerSign(data.toString(), socket); }); socket.on("error", (error) => { console.error("Socket error:", error); }); socket.on("end", () => { console.log("Client disconnected"); });});server.listen(1337, "127.0.0.1");console.log("Fee delegate service started ...");
服務器監聽端口為 1337
。
當有 "數據 "傳入時,它會用 "付費者私鑰 "對 "數據 "進行簽名,並將其發送到 Kaia 區塊鏈。 It assumes that the data
is senderTxHashRLP
from the sender_client.js
.
4. 運行示例
準備兩個終端,一個是 sender_client.js
終端,另一個是 feepayer_server.js
終端。
4.1 運行 feepayer_server.js
Run the command below to start the fee payer's server:
node feepayer_server.js// outputFee delegate service started ...
服務器啟動並監聽 1337 端口。
4.2 運行 sender_client.js
讓我們運行 sender_client.js
發送一筆委託收費交易。
$ node sender_client.js// output{ type: 9, to: '0x3a388d3fD71A0d9722c525E17007DdCcc41e1C47', value: 10000000000000000n, from: '0x7D3C7202582299470F2aD3DDCB8EF2F45407F871', nonce: 202, gasLimit: 52500, gasPrice: '27500000000', chainId: '1001'}senderTxHashRLP 0x09f88681ca85066720b30082cd14943a388d3fd71a0d9722c525e17007ddccc41e1c47872386f26fc10000947d3c7202582299470f2ad3ddcb8ef2f45407f871f847f8458207f6a0820d11029771f2fa368ce11da01f1c9e7f4de6d48915074d149e132692f9d63ea0131c62470a6799dfc5d7e3a7ac8d0a4f3b8fb8b59110ca5dabb26a9ee409f274Connected to fee delegated serviceReceived data from server: This is fee delegating, serviceFee payer is 0x88311cD55B656D2502b50f62E83F8279c1641e70
它將用 "發送方 "私鑰簽署交易,並將簽署後的交易發送到費用委託服務(即費用支付方的服務器)。 Then it will receive the response from the fee delegate service including the Fee payer
address, Tx hash
. Tx hash
is hash of a transaction submitted to the Kaia network.
4.3 Check feepayer_server.js
On the server's console, you will see below outputs. It prints the transaction receipt from the Kaia.
$ node feepayer_server.jsFee delegate service started ...Client is connected ...Received data from client: 0x09f88681ca85066720b30082cd14943a388d3fd71a0d9722c525e17007ddccc41e1c47872386f26fc10000947d3c7202582299470f2ad3ddcb8ef2f45407f871f847f8458207f6a0820d11029771f2fa368ce11da01f1c9e7f4de6d48915074d149e132692f9d63ea0131c62470a6799dfc5d7e3a7ac8d0a4f3b8fb8b59110ca5dabb26a9ee409f274sentTx TransactionResponse {… to: '0x3a388d3fD71A0d9722c525E17007DdCcc41e1C47', from: '0x7D3C7202582299470F2aD3DDCB8EF2F45407F871', contractAddress: null, hash: '0x7cb1e8d20b4db7d9db1abc094781e1af83a9391153aab8cc935510639a548222', index: 0, blockHash: '0x50d3d7e143579e17dbc17b761c8e04331c6d4d950fe7563ac9a79d42a649de0a', blockNumber: 177078710, logsBloom: '0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000', gasUsed: 31000n, blobGasUsed: null, cumulativeGasUsed: 31000n, gasPrice: 27500000000n, blobGasPrice: null, type: 0, status: 1, root: undefined}
4.4 View on Kaiascan
You can also find the above transaction on Kaiascan.
It shows that the transaction is TxTypeFeeDelegatedValueTransfer
and Fee payer
is 0x88311cd55b656d2502b50f62e83f8279c1641e70
or feepayerAddress
that you entered, while From
is a different address which should be the senderAddress
in above example.