aptos初体验
Aptos作为有背景有技术的新公链最近可谓吸满了投资，赚足了眼球。其从Libra和Diem继承来的技术又支持其超高tps和高安全高稳定的合约机制，官网上明晃晃的"Building the safest and most scalable Layer 1 blockchain."彰显着这群前FB工程师的野心。我们今天便浅尝一下这个技术和资本共同的宠儿，Aptos和Move语言。
Aptos是一条不兼容evm的Layer1公链，其特点是高安全性，高稳定性，高扩展性以及高达100k+的恐怖tps。独特的存储模型使其可能在NFT和GameFi领域大展身手。合约语言为Move，是一个基于Rust的内存安全型合约语言，在Libra时期便已经成型，目前Sui和Aptos都在使用它构造"有史以来最高性能的公链"。据社交媒体透露，现在Move语言开发者的工资时薪已经高达$1200，这让我不禁留下了悔恨的口水，哦不是，泪水。
这篇文章将从头到尾体验一下在Aptos链上发起交易和编写合约，不需要编写代码。通过运行，测试aptos官方事例，阅读 move代码，感受这个号称最安全Layer1链的魅力。官方事例给出了TypeScript，Rust，和Python三种语言的代码，考虑到aptos-core本身是由Rust编写而且其合约语言Move又与Rust极度相似，本文使用Rust事例进行讲解。
0.准备工作
安装rust，不多做介绍
下载aptos-core代码库 git clone https://github.com/aptos-labs/aptos-core.git
进入代码库cd aptos-core
切换分支git checkout --track origin/devnet
运行启动脚本，构建开发环境./scripts/dev_setup.sh
下载Aptos Commandline tool命令行工具cargo install --git https://github.com/aptos-labs/aptos-core.git aptos
1.发起交易
这一部分代码在aptos-core/developer-docs-site/static/examples/rust/first_transaction里：
1.1 创建账户
关于aptos的账户系统详情可以看官方文档: https://aptos.dev/concepts/basics-accounts
pub struct Account {
signing_key: SecretKey,
}
impl Account {
/// Represents an account as well as the private, public key-pair for the Aptos blockchain.
pub fn new(priv_key_bytes: Option<Vec<u8>>) -> Self {
let signing_key = match priv_key_bytes {
Some(key) => SecretKey::from_bytes(&key).unwrap(),
None => {
let mut rng = rand::rngs::StdRng::from_seed(OsRng.gen());
let mut bytes = [0; 32];
rng.fill_bytes(&mut bytes);
SecretKey::from_bytes(&bytes).unwrap()
}
};
Account { signing_key }
}
/// Returns the address associated with the given account
pub fn address(&self) -> String {
self.auth_key()
}
/// Returns the auth_key for the associated account
pub fn auth_key(&self) -> String {
let mut sha3 = Sha3::v256();
sha3.update(PublicKey::from(&self.signing_key).as_bytes());
sha3.update(&vec![0u8]);
let mut output = [0u8; 32];
sha3.finalize(&mut output);
hex::encode(output)
}
/// Returns the public key for the associated account
pub fn pub_key(&self) -> String {
hex::encode(PublicKey::from(&self.signing_key).as_bytes())
}
}
1.2 准备一个REST接口包装器
构造一个RestClient，并连接测试网 https://fullnode.devnet.aptoslabs.com
#[derive(Clone)]
pub struct RestClient {
url: String,
}
///RestClient中的方法
impl RestClient {
//从url初始化client
pub fn new(url: String) -> Self {
Self { url }
}
///Rest请求的具体实现,下边详细讲解
.......
}
1.2.1 读取账户信息
以下代码是通过账户地址读取账户信息的接口实现
值得注意的是account_resource接口，aptos的任何账户都有data存储，可以用来储存货币/NFT等等，这些信息被称为resource。
如果我们要查询某个账户的AptosCoin余额，就要定位到0x1::coin::CoinStore<0x1::aptos_coin::AptosCoin，查询对应的resource数据，在1.2.3中account_balance就是复用了该接口。
这里的0x1实际上是一个account地址，因为AptosCoin是root账户0x1发行的，所以会出现0x1这种写法，类似写法在下文也会出现。而coin::CoinStore<>是aptos对代币的resource的一种特殊处理，以提供安全性。这样的话可以理解为查询该账户下，由0x1发行的AptosCoin的数目。
详情见aptos-labs/aptos-core/blob/main/aptos-move/framework/aptos-framework/sources/coin.move
/// 返回账户的私钥和序列码sequence_number，详情见https://aptos.dev/concepts/basics-accounts
pub fn account(&self, account_address: &str) -> serde_json::Value {
let res =
reqwest::blocking::get(format!("{}/accounts/{}", self.url, account_address)).unwrap();
if res.status() != 200 {
assert_eq!(
res.status(),
200,
"{} - {}",
res.text().unwrap_or("".to_string()),
account_address,
);
}
res.json().unwrap()
}
/// 返回账户所有相关信息
pub fn account_resource(
&self,
account_address: &str,
resource_type: &str,
) -> Option<serde_json::Value> {
let res = reqwest::blocking::get(format!(
"{}/accounts/{}/resource/{}",
self.url, account_address, resource_type,
))
.unwrap();
if res.status() == 404 {
None
} else if res.status() != 200 {
assert_eq!(
res.status(),
200,
"{} - {}",
res.text().unwrap_or("".to_string()),
account_address,
);
unreachable!()
} else {
Some(res.json().unwrap())
}
}
1.2.2 交易相关操作(生成，签名，提交)
/// Generates a transaction request that can be submitted to produce a raw transaction that can be signed, which upon being signed can be submitted to the blockchain.
pub fn generate_transaction(
&self,
sender: &str,
payload: serde_json::Value,
) -> serde_json::Value {
let account_res = self.account(sender);
let seq_num = account_res
.get("sequence_number")
.unwrap()
.as_str()
.unwrap()
.parse::<u64>()
.unwrap();
// Unix timestamp, in seconds + 10 minutes
let expiration_time_secs = SystemTime::now()
.duration_since(UNIX_EPOCH)
.expect("Time went backwards")
.as_secs()
+ 600;
serde_json::json!({
"sender": format!("0x{}", sender),
"sequence_number": seq_num.to_string(),
"max_gas_amount": "1000",
"gas_unit_price": "1",
"gas_currency_code": "XUS",
"expiration_timestamp_secs": expiration_time_secs.to_string(),
"payload": payload,
})
}
/// Converts a transaction request produced by `generate_transaction` into a properly signed transaction, which can then be submitted to the blockchain.
pub fn sign_transaction(
&self,
account_from: &mut Account,
mut txn_request: serde_json::Value,
) -> serde_json::Value {
let res = reqwest::blocking::Client::new()
.post(format!("{}/transactions/signing_message", self.url))
.body(txn_request.to_string())
.send()
.unwrap();
if res.status() != 200 {
assert_eq!(
res.status(),
200,
"{} - {}",
res.text().unwrap_or("".to_string()),
txn_request.as_str().unwrap_or(""),
);
}
let body: serde_json::Value = res.json().unwrap();
let to_sign_hex = Box::new(body.get("message").unwrap().as_str()).unwrap();
let to_sign = hex::decode(&to_sign_hex[2..]).unwrap();
let signature: String = ExpandedSecretKey::from(&account_from.signing_key)
.sign(&to_sign, &PublicKey::from(&account_from.signing_key))
.encode_hex();
let signature_payload = serde_json::json!({
"type": "ed25519_signature",
"public_key": format!("0x{}", account_from.pub_key()),
"signature": format!("0x{}", signature),
});
txn_request
.as_object_mut()
.unwrap()
.insert("signature".to_string(), signature_payload);
txn_request
}
/// Submits a signed transaction to the blockchain.
pub fn submit_transaction(&self, txn_request: &serde_json::Value) -> serde_json::Value {
let res = reqwest::blocking::Client::new()
.post(format!("{}/transactions", self.url))
.body(txn_request.to_string())
.header("Content-Type", "application/json")
.send()
.unwrap();
if res.status() != 202 {
assert_eq!(
res.status(),
202,
"{} - {}",
res.text().unwrap_or("".to_string()),
txn_request.as_str().unwrap_or(""),
);
}
res.json().unwrap()
}
/// Submits a signed transaction to the blockchain.
pub fn execution_transaction_with_payload(
&self,
account_from: &mut Account,
payload: serde_json::Value,
) -> String {
let txn_request = self.generate_transaction(&account_from.address(), payload);
let signed_txn = self.sign_transaction(account_from, txn_request);
let res = self.submit_transaction(&signed_txn);
res.get("hash").unwrap().as_str().unwrap().to_string()
}
pub fn transaction_pending(&self, transaction_hash: &str) -> bool {
let res = reqwest::blocking::get(format!("{}/transactions/{}", self.url, transaction_hash))
.unwrap();
if res.status() == 404 {
return true;
}
if res.status() != 200 {
assert_eq!(
res.status(),
200,
"{} - {}",
res.text().unwrap_or("".to_string()),
transaction_hash,
);
}
res.json::<serde_json::Value>()
.unwrap()
.get("type")
.unwrap()
.as_str()
.unwrap()
== "pending_transaction"
}
/// Waits up to 10 seconds for a transaction to move past pending state.
pub fn wait_for_transaction(&self, txn_hash: &str) {
let mut count = 0;
while self.transaction_pending(txn_hash) {
assert!(count < 10, "transaction {} timed out", txn_hash);
thread::sleep(Duration::from_secs(1));
count += 1;
}
}
1.2.3 构造交易逻辑
一个是account_balance，使用account_resource调用AptosCoin资源查询 另一个是transfer，使用的是0x1::coin::transfer也就是coin共有方法transfer
/// Returns the test coin balance associated with the account
pub fn account_balance(&self, account_address: &str) -> Option<u64> {
self.account_resource(
account_address,
"0x1::coin::CoinStore<0x1::aptos_coin::AptosCoin>",
)
.unwrap()["data"]["coin"]["value"]
.as_str()
.and_then(|s| s.parse::<u64>().ok())
}
/// Transfer a given coin amount from a given Account to the recipient's account address.
/// Returns the sequence number of the transaction used to transfer
pub fn transfer(&self, account_from: &mut Account, recipient: &str, amount: u64) -> String {
let payload = serde_json::json!({
"type": "script_function_payload",
"function": "0x1::coin::transfer",
"type_arguments": ["0x1::aptos_coin::AptosCoin"],
"arguments": [format!("0x{}", recipient), amount.to_string()]
});
let txn_request = self.generate_transaction(&account_from.address(), payload);
let signed_txn = self.sign_transaction(account_from, txn_request);
let res = self.submit_transaction(&signed_txn);
res.get("hash").unwrap().as_str().unwrap().to_string()
}
}
1.3 准备一个水龙头接口包装器
pub struct FaucetClient {
url: String,
rest_client: RestClient,
}
impl FaucetClient {
/// 水龙头可以创建账户并给其分配资产，这是一个包装器
pub fn new(url: String, rest_client: RestClient) -> Self {
Self { url, rest_client }
}
/// 给传入用户铸币
pub fn fund_account(&self, auth_key: &str, amount: u64) {
let res = reqwest::blocking::Client::new()
.post(format!(
"{}/mint?amount={}&auth_key={}",
self.url, amount, auth_key
))
.send()
.unwrap();
if res.status() != 200 {
assert_eq!(
res.status(),
200,
"{}",
res.text().unwrap_or("".to_string()),
);
}
for txn_hash in res.json::<serde_json::Value>().unwrap().as_array().unwrap() {
self.rest_client
.wait_for_transaction(txn_hash.as_str().unwrap())
}
}
}
1.4 运行测试
fn main() -> () {
let rest_client = RestClient::new(TESTNET_URL.to_string());
let faucet_client = FaucetClient::new(FAUCET_URL.to_string(), rest_client.clone());
//创建两个账户Alice和Bob，并用水龙头给Alice赚一笔账
let mut alice = Account::new(None);
let bob = Account::new(None);
println!("\n=== Addresses ===");
println!("Alice: 0x{}", alice.address());
println!("Bob: 0x{}", bob.address());
faucet_client.fund_account(&alice.auth_key().as_str(), 1_000_000);
faucet_client.fund_account(&bob.auth_key().as_str(), 0);
//调用account_balance查询账户余额
println!("\n=== Initial Balances ===");
println!("Alice: {:?}", rest_client.account_balance(&alice.address()));
println!("Bob: {:?}", rest_client.account_balance(&bob.address()));
// Alice构造一笔向bob转账1000的交易并提交等待完成
let tx_hash = rest_client.transfer(&mut alice, &bob.address(), 1_000);
rest_client.wait_for_transaction(&tx_hash);
//调用account_balance查询账户余额
println!("\n=== Final Balances ===");
println!("Alice: {:?}", rest_client.account_balance(&alice.address()));
println!("Bob: {:?}", rest_client.account_balance(&bob.address()));
}
运行cargo run --bin first-transaction(运行前确保您在aptos-core/developer-docs-site/static/examples/rust目录下)
1.5 输出
可以看到转账成功后Alice和Bob的余额(去掉gas费)
=== Addresses ===
Alice: e26d69b8d3ff12874358da6a4082a2ac
Bob: c8585f009c8a90f22c6b603f28b9ed8c
=== Initial Balances ===
Alice: 1000000000
Bob: 0
=== Final Balances ===
Alice: 999998957
Bob: 1000
2.玩转合约
aptos链使用Move语言编写合约，其特点是安全稳定，语法上与Rust很像。
我们现在构建一个新的合约，在aptos的世界里称为module。
需要完成以下几个步骤：
1.编写，编译，测试module 2.部署module 3.与module的资源(存储区)交互
2.1 阅读合约代码
我们先进到aptos-move/move-examples/hello_blockchain目录里，我们暂且称其为“Move目录”，方便之后切换目录指称。
在这个目录里我们可以看到这个sources/HelloBlockchain.move文件，这个module可以让账户可以创建并修改一个String类型的资源，每个用户都只能操作自己的资源。
module HelloBlockchain::Message {
use std::string;
use std::error;
use std::signer;
struct MessageHolder has key {
message: string::String,
}
public entry fun set_message(account: signer, message_bytes: vector<u8>)
acquires MessageHolder {
let message = string::utf8(message_bytes);
let account_addr = signer::address_of(&account);
if (!exists<MessageHolder>(account_addr)) {
move_to(&account, MessageHolder {
message,
})
} else {
let old_message_holder = borrow_global_mut<MessageHolder>(account_addr);
old_message_holder.message = message;
}
}
}
在上述代码中有两个关键，一个是结构体MessageHolder 一个是函数 set_message。 set_message 是一个script函数，允许被交易直接调用，调用它之后函数会确认账户是否有MessageHolder 资源，没有的话就创建一个并把信息写入，有的话就覆盖掉。
2.2测试合约
Move测试可以直接写在合约里，我们加上了一个sender_can_set_message测试函数，用cargo test进行测试。
运行 cargo test test_hello_blockchain -p move-examples -- --exact 即可。
#[test(account = @0x1)]
public(script) fun sender_can_set_message(account: signer) acquires MessageHolder {
let addr = Signer::address_of(&account);
set_message(account, b"Hello, Blockchain");
assert!(
get_message(addr) == string::utf8(b"Hello, Blockchain"),
0
);
}
2.3部署合约
现在我们回到之前transaction样例的同级目录，找到developer-docs-site/static/examples/rust/hello_blockchain查看部署和交互module的代码。这会复用一些上一节的函数。这一节我们只讨论新功能，比如部署module，set_message交易，以及读取MessageHolder::message资源，部署module和提交交易的区别就只有payload，我们开始看吧：
2.3.1 部署module
pub struct HelloBlockchainClient {
pub rest_client: RestClient,
}
impl HelloBlockchainClient {
/// Represents an account as well as the private, public key-pair for the Aptos blockchain.
pub fn new(url: String) -> Self {
Self {
rest_client: RestClient::new(url),
}
}
/// Publish a new module to the blockchain within the specified account
pub fn publish_module(&self, account_from: &mut Account, module_hex: &str) -> String {
let payload = serde_json::json!({
"type": "module_bundle_payload",
"modules": [{"bytecode": format!("0x{}", module_hex)}],
});
self.rest_client
.execution_transaction_with_payload(account_from, payload)
}
2.3.2 读取资源
Module 发布在一个地址上，就是下边的 contract_address。上一节转移Coin时候的0x1也是发布地址。
/// Retrieve the resource Message::MessageHolder::message
pub fn get_message(&self, contract_address: &str, account_address: &str) -> Option<String> {
let module_type = format!("0x{}::Message::MessageHolder", contract_address);
self.rest_client
.account_resource(account_address, &module_type)
.map(|value| value["data"]["message"].as_str().unwrap().to_string())
}
2.3.3 修改资源
Module必须暴露出script函数才能初始化和修改资源，script可以被交易调用。
/// Potentially initialize and set the resource Message::MessageHolder::message
pub fn set_message(
&self,
contract_address: &str,
account_from: &mut Account,
message: &str,
) -> String {
let message_hex = hex::encode(message.as_bytes());
let payload = serde_json::json!({
"type": "script_function_payload",
"function": format!("0x{}::Message::set_message", contract_address),
"type_arguments": [],
"arguments": [message_hex]
});
self.rest_client
.execution_transaction_with_payload(account_from, payload)
}
2.4 初始化并交互
进入 developer-docs-site/static/examples/rust，我们姑且称为"App 目录"
运行 cargo run --bin hello-blockchain -- Message.mv
过了一会，控制台会输出Alice与Bob的账户信息并显示Update the module with Alice's address, build, copy to the provided path, and press enter. ，记录下Alice的地址，不要关闭
这时我们另起一个控制台，进入"Move目录"，将hello_blockchain/move.toml中的 HelloBlockChain='_'配置为Alice地址。
运行aptos move compile --package-dir . --named-addresses HelloBlockchain=0x{Alice的地址}
Module编译成功，将build/Examples/bytecode_modules/Message.mv复制一份到developer-docs-site/static/examples/rust
在"App 目录"的控制台输入回车让它继续运行
输出如果类似这样就是成功了：
=== Addresses ===
Alice: 11c32982d04fbcc79b694647edff88c5b5d5b1a99c9d2854039175facbeefb40
Bob: 7ec8f962139943bc41c17a72e782b7729b1625cf65ed7812152a5677364a4f88
=== Initial Balances ===
Alice: 10000000
Bob: 10000000
Update the module with Alice's address, build, copy to the provided path, and press enter.
=== Testing Alice ===
Publishing...
Initial value: None
Setting the message to "Hello, Blockchain"
New value: Hello, Blockchain
=== Testing Bob ===
Initial value: None
Setting the message to "Hello, Blockchain"
New value: Hello, Blockchain
证明了Alice和Bob都新创建了Message资源并置为"Hello, Blockchain"
3.相关资料
Aptos 官方文档：https://aptos.dev Move手册：https://move-language.github.io/move/ 区块链浏览器：https://explorer.devnet.aptos.dev api文档：https://fullnode.devnet.aptoslabs.com/spec.html#/