简述
POA Bridge是在两个以太坊链之间转移资产代币（原生和ERC20 / ERC677令牌）的解决方案。
资产代币通常有两个作用：
· 代币可以作为长期投资进行交易、交换或保存的用途。
· 可以在Dapp上进行使用代币（投票，抵押等）
这两种用途都需要不同的网络属性来实现最佳体验，货币使用可能需要强大的网络安全性和活跃性，以及访问大型资产网络以促进交易，而应用程序使用需要更快、更便宜的交易以获得更好的用户体验。
侧链和桥接器作为第2层可扩展性解决方案的一部分，并尝试解决可扩展性和UX问题，因为以太坊主网通常被认为太慢（15 tx / sec）而且gas费用过于昂贵不能为（游戏或社交应用程序）提供良好的用户体验。在这种情况下，一般流程如下：
· 用户在主链上购买代币
· 用户通过桥将他的代币转移到侧链（提示：代币锁定在主链上，在侧链上重新铸造）
· 用户以快速有效的方式使用代币。也许从其他用户那里赚取或送出一些代币
· 用户决定撤回侧链中的代币并通过桥接器将其传输回主链（在主链上解锁并在侧链上烧掉的代币）
· 用户在主链上出售他的代币
在本教程中，我们将学习如何在两个网络上部署代币（RinkeBy网络作为主链，POA Sokol作为侧链），部署并使用桥接器（ERC20 <> ERC20）让用户资产从一个网络转移到另一个网络。
在开始之前，您需要在计算机上安装以下程序：
1. Git
2. NodeJS/NPM
3. Yarn
4. Docker and Docker-Compose
5. Metamask
6. Truffle
$ npm install -g truffle
$ truffle version
Truffle v5.0.20 (core: 5.0.20)
Solidity v0.5.0 (solc-js)
Node v8.15.1
Web3.js v1.0.0-beta.37
步骤1：在主链（Rinkeby网络）上部署名为BRidge Token BRT的ERC20令牌
1、让我们首先为我们的ERC20 BRT创建一个项目文件夹并初始化一个Truffle项目。
$ mkdir token
$ cd token
$ truffle init
2、然后我们将安装Open-Zeppelin Solidity库，其中经过充分测试和审计的可重用智能合约。
$ npm init -y
$ npm install openzeppelin-solidity --save-exact
3、创建一个包含的合同文件./contacts/BridgeToken.sol
// BridgeToken.sol
pragma solidity ^0.5.8;
import "openzeppelin-solidity/contracts/token/ERC20/ERC20Mintable.sol";
contract BridgeToken is ERC20Mintable {
string public constant name = "Bridge Token";
string public constant symbol = "BRT";
uint8 public constant decimals = 18;
}
要确保您的智能合约编译，您可以执行命令truffle compile。
4、在RinkeBy网络上部署智能合约
注意：确保用于部署合同的帐户由RinkeBy ethers资助。
我们的智能合约编译完成，我们就需要部署它。为此，我们首先需要完成脚本迁移，创建一个文件./migrations/2_deploy_contract.js
// 2_deploy_contract.js
const BridgeToken = artifacts.require("./BridgeToken.sol");
module.exports = function(deployer, network, accounts) {
// Deploy the smart contract
deployer.deploy(BridgeToken, {from: accounts[0]}).then(function(instance) {
// Mint 100 tokens
return instance.mint(accounts[0], web3.utils.toBN("100000000000000000000"), {from: accounts[0]});
});
};
脚本迁移后并部署合约，另外还创建了100个BRT代币并将其分发到部署者帐户。
下一步包括配置到rinkeby网络的连接，以便部署智能合约。
安装以下依赖项（dotenv用于管理环境变量，而truffle-hdwallet-provider用于从来自助记符的帐户签署事务）
$ npm install --save dotenv truffle-hdwallet-provider
创建一个文件./.env来存储一些私人信息，我们不想在任何地方共享（gitignore这个文件）
· infura是以太坊的公共门户。如果您还没有帐户，我建议您创建一个帐户，并在此文件中跳过您的API密钥（项目ID）。
· 助记符是12个单词组成的短语，象征着一把私钥。 你可以在Metamask中找到它。
// .env
INFURA_API_KEY=044443611111111e19e03433333309923
MNEMONIC=twelve words you can find in metamask/settings/reveal seed words
最后，让我们配置与RinkeBy网络的连接。编辑文件./truffle.js
// truffle.js
require('dotenv').config();
const HDWalletProvider = require("truffle-hdwallet-provider");
module.exports = {
networks: {
development: {
host: "localhost",
port: 8545,
network_id: "*"
},
rinkeby: {
provider: new HDWalletProvider(process.env.MNEMONIC, "https://rinkeby.infura.io/v3/" + process.env.INFURA_API_KEY),
network_id: 4,
gas: 4500000
}
}
};
要在rinkeby网络上部署智能合约，请运行命令（这可能需要一段时间）：
$ truffle migrate --network rinkeby
Compiling your contracts...
===========================
> Compiling ./contracts/BridgeToken.sol
> Compiling ./contracts/Migrations.sol
> Compiling openzeppelin-solidity/contracts/access/Roles.sol
> Compiling openzeppelin-solidity/contracts/access/roles/MinterRole.sol
> Compiling openzeppelin-solidity/contracts/math/SafeMath.sol
> Compiling openzeppelin-solidity/contracts/token/ERC20/ERC20.sol
> Compiling openzeppelin-solidity/contracts/token/ERC20/ERC20Mintable.sol
> Compiling openzeppelin-solidity/contracts/token/ERC20/IERC20.sol
> Artifacts written to /home/gjeanmart/workspace/tutorials/bridge_token/build/contracts
> Compiled successfully using:
- solc: 0.5.8+commit.23d335f2.Emscripten.clang
Migrations dry-run (simulation)
===============================
> Network name: 'rinkeby-fork'
> Network id: 4
> Block gas limit: 0x7244c0
1_initial_migration.js
======================
Deploying 'Migrations'
----------------------
> block number: 4502550
> block timestamp: 1559667907
> account: 0xF0f15Cedc719B5A55470877B0710d5c7816916b1
> balance: 33.578282390129999997
> gas used: 246393
> gas price: 2 gwei
> value sent: 0 ETH
> total cost: 0.000492786 ETH
-------------------------------------
> Total cost: 0.000492786 ETH
2_deploy_contract.js
====================
Deploying 'BridgeToken'
-----------------------
> block number: 4502552
> block timestamp: 1559667919
> account: 0xe9B0E206C8cA079bca49F0120abfD02760093612
> balance: 99.996785462
> gas used: 1607269
> gas price: 2 gwei
> value sent: 0 ETH
> total cost: 0.003214538 ETH
-------------------------------------
> Total cost: 0.003214538 ETH
Summary
=======
> Total deployments: 2
> Final cost: 0.003707324 ETH
Starting migrations...
======================
> Network name: 'rinkeby'
> Network id: 4
> Block gas limit: 0x724802
1_initial_migration.js
======================
Deploying 'Migrations'
----------------------
> transaction hash: 0x44dbbf18d316adb29143d1b3341c1e28b297d144411ee98cb23017270f77b9ed
> Blocks: 1 Seconds: 9
> contract address: 0xAC96dc3AC9baB86c7d89a5868096394CB708a6a0
> block number: 4502551
> block timestamp: 1559667943
> account: 0xF0f15Cedc719B5A55470877B0710d5c7816916b1
> balance: 33.573547316129999997
> gas used: 261393
> gas price: 20 gwei
> value sent: 0 ETH
> total cost: 0.00522786 ETH
> Saving migration to chain.
> Saving artifacts
-------------------------------------
> Total cost: 0.00522786 ETH
2_deploy_contract.js
====================
Deploying 'BridgeToken'
-----------------------
> transaction hash: 0x80dc122178131cbd040e90b667cc1d11a47d21abf8ebf17c80232b1c4c5f33df
> Blocks: 2 Seconds: 21
> contract address: 0x40A6a864133985E1146DDfEb48c7391CD07596F5
> block number: 4502554
> block timestamp: 1559667988
> account: 0xF0f15Cedc719B5A55470877B0710d5c7816916b1
> balance: 33.540261476129999997
> gas used: 1622269
> gas price: 20 gwei
> value sent: 0 ETH
> total cost: 0.03244538 ETH
> Saving migration to chain.
> Saving artifacts
-------------------------------------
> Total cost: 0.03244538 ETH
Summary
=======
> Total deployments: 2
> Final cost: 0.03767324 ETH
因此，我们可以将我们的智能合约BridgeToken标识为已部署在地址0x40A6a864133985E1146DDfEb48c7391CD07596F5（请参阅block explorer）
步骤2：初始化monorepo令牌桥
在第二步中，我们将初始化GitHub mono-repository，以便按以下步骤安装每个组件。
1、复制repo
$ cd ../
$ git clone --recursive https://github.com/poanetwork/tokenbridge
$ cd ./tokenbridge/
2、安装依赖项
$ yarn install && yarn install:deploy
步骤3：配置和部署网桥合约
在第三步中，我们将部署必要的合约以启用ERC20到ERC20网桥。
1、转到合约文件夹
$ cd ./contracts/
2、编译智能合约
$ npm run compile
在./deploy/.env中创建配置文件
注1：要更改以下属性
<PRIVATE_KEY>负责部署，管理合同和验证转移的帐户
<ACCOUNT_ADMIN>负责部署，管理合同和验证转移的帐户。
<ERC20_TOKEN_ADDRESS>上面部署的ERC20令牌的地址。
注2：出于本教程的原因，我们决定尽可能简化配置（一个帐户管理和验证）
注3：确保账户ACCOUNT_ADMIN由RinkeBy ethers和POA Sokol ethers资助。
注4：未配置区块奖励（奖励令牌）。
BRIDGE_MODE=ERC_TO_ERC
#BRIDGE_MODE=NATIVE_TO_ERC
# If Home network does not support byzantium fork, should use contracts compiled for spuriousDragon
#HOME_EVM_VERSION=spuriousDragon
# If Foreign network does not support byzantium fork, should use contracts compiled for spuriousDragon
#FOREIGN_EVM_VERSION=spuriousDragon
DEPLOYMENT_ACCOUNT_PRIVATE_KEY=<PRIVATE_KEY>
DEPLOYMENT_GAS_LIMIT_EXTRA=0.2
HOME_DEPLOYMENT_GAS_PRICE=10000000000
FOREIGN_DEPLOYMENT_GAS_PRICE=10000000000
GET_RECEIPT_INTERVAL_IN_MILLISECONDS=3000
BRIDGEABLE_TOKEN_NAME="Bridge Token"
BRIDGEABLE_TOKEN_SYMBOL=BRT
BRIDGEABLE_TOKEN_DECIMALS=18
HOME_RPC_URL=https://sokol.poa.network
HOME_BRIDGE_OWNER=<ACCOUNT_ADMIN>
HOME_VALIDATORS_OWNER=<ACCOUNT_ADMIN>
HOME_UPGRADEABLE_ADMIN=<ACCOUNT_ADMIN>
HOME_DAILY_LIMIT=30000000000000000000000000
HOME_MAX_AMOUNT_PER_TX=1500000000000000000000000
HOME_MIN_AMOUNT_PER_TX=500000000000000000
HOME_REQUIRED_BLOCK_CONFIRMATIONS=1
HOME_GAS_PRICE=1000000000
BLOCK_REWARD_ADDRESS=0x0000000000000000000000000000000000000000
FOREIGN_RPC_URL=https://rinkeby.infura.io
FOREIGN_BRIDGE_OWNER=<ACCOUNT_ADMIN>
FOREIGN_VALIDATORS_OWNER=<ACCOUNT_ADMIN>
FOREIGN_UPGRADEABLE_ADMIN=<ACCOUNT_ADMIN>
FOREIGN_DAILY_LIMIT=15000000000000000000000000
FOREIGN_MAX_AMOUNT_PER_TX=750000000000000000000000
FOREIGN_MIN_AMOUNT_PER_TX=500000000000000000
FOREIGN_REQUIRED_BLOCK_CONFIRMATIONS=8
FOREIGN_GAS_PRICE=10000000000
#for bridge erc_to_erc and erc_to_native mode
ERC20_TOKEN_ADDRESS=<ERC20_TOKEN_ADDRESS>
# Only for for erc_to_erc mode
ERC20_EXTENDED_BY_ERC677=false
REQUIRED_NUMBER_OF_VALIDATORS=1
#If several validators are used, list them separated by space without quotes
#E.g. VALIDATORS=0x 0x 0x
VALIDATORS=<ACCOUNT_ADMIN>
#Set to ONE_DIRECTION or BOTH_DIRECTIONS if fee will be charged on home side, set to false otherwise
HOME_REWARDABLE=false
# Valid only for rewards on erc_to_native mode. Supported values are BRIDGE_VALIDATORS_REWARD and POSDAO_REWARD
HOME_FEE_MANAGER_TYPE=
#Set to ONE_DIRECTION or BOTH_DIRECTIONS if fee will be charged on foreign side, set to false otherwise
FOREIGN_REWARDABLE=false
#If HOME_REWARDABLE or FOREIGN_REWARDABLE set to true, list validators accounts were rewards should be transferred separated by space without quotes
#E.g. VALIDATORS_REWARD_ACCOUNTS=0x 0x 0x
VALIDATORS_REWARD_ACCOUNTS=0x
# Fee to be taken for every transaction directed from the Home network to the Foreign network
# E.g. 0.1% fee
HOME_TRANSACTIONS_FEE=0.001
# Fee to be taken for every transaction directed from the Foreign network to the Home network
FOREIGN_TRANSACTIONS_FEE=0.001
#for bridge native_to_erc, erc_to_erc mode
DEPLOY_REWARDABLE_TOKEN=false
DPOS_STAKING_ADDRESS=0x0000000000000000000000000000000000000000
4、部署Bridge配置
$ ./deploy.sh
(...)
Deployment has been completed.
[ Home ] HomeBridge: 0xc4e7cA947521f331969e41CC7c99ADa22F2C7F9C at block 9044640
[ Home ] ERC677 Bridgeable Token: 0xEa3acD04DdaF1F1A5Ae1B9f5f690123aA4E19B36
[ Foreign ] ForeignBridge: 0xeb2dbC5AB9380A3517AcA9d8CA0c39873e569a93 at block 4503560
[ Foreign ] ERC20 Token: 0x40A6a864133985E1146DDfEb48c7391CD07596F5
Contracts Deployment have been saved to `bridgeDeploymentResults.json`
{
"homeBridge": {
"address": "0xc4e7cA947521f331969e41CC7c99ADa22F2C7F9C",
"deployedBlockNumber": 9044640,
"erc677": {
"address": "0xEa3acD04DdaF1F1A5Ae1B9f5f690123aA4E19B36"
}
},
"foreignBridge": {
"address": "0xeb2dbC5AB9380A3517AcA9d8CA0c39873e569a93",
"deployedBlockNumber": 4503560
}
}
步骤4：配置和部署网桥Oracle
1、转到“Oracle文件夹”
$ cd ../oracle
2、在./.env中创建配置文件
注意1：打开保存的JSON文件bridgeDeploymentResults.json以获取本地和外部桥接合约地址和部署区块编号。
{
"homeBridge": {
"address": "0xc4e7cA947521f331969e41CC7c99ADa22F2C7F9C",
"deployedBlockNumber": 9044640,
"erc677": {
"address": "0xEa3acD04DdaF1F1A5Ae1B9f5f690123aA4E19B36"
}
},
"foreignBridge": {
"address": "0xeb2dbC5AB9380A3517AcA9d8CA0c39873e569a93",
"deployedBlockNumber": 4503560
}
}
注2：要更改以下属性
<PRIVATE_KEY>负责部署，管理合同和验证转移的帐户
<ACCOUNT_ADMIN>负责部署，管理合同和验证转移的帐户
<ERC20_TOKEN_ADDRESS>上面部署的ERC20令牌的地址。
注3：出于本教程的原因，我们决定尽可能简化配置（一个帐户管理和验证）
注意4：确保帐户ACCOUNT_ADMIN由RinkeBy ethers和POA sokol ethers资助。
BRIDGE_MODE=ERC_TO_ERC
HOME_POLLING_INTERVAL=5000
FOREIGN_POLLING_INTERVAL=1000
ALLOW_HTTP=yes
HOME_RPC_URL=https://sokol.poa.network
FOREIGN_RPC_URL=https://rinkeby.infura.io
HOME_BRIDGE_ADDRESS=<bridgeDeploymentResults.json / homeBridge / address>
FOREIGN_BRIDGE_ADDRESS=<bridgeDeploymentResults.json / foreignBridge / address>
ERC20_TOKEN_ADDRESS=<ERC20_TOKEN_ADDRESS>
VALIDATOR_ADDRESS=<ACCOUNT_ADMIN>
VALIDATOR_ADDRESS_PRIVATE_KEY=<PRIVATE_KEY>
HOME_GAS_PRICE_ORACLE_URL=https://gasprice.poa.network/
HOME_GAS_PRICE_SPEED_TYPE=standard
HOME_GAS_PRICE_FALLBACK=1000000000
HOME_GAS_PRICE_UPDATE_INTERVAL=600000
FOREIGN_GAS_PRICE_ORACLE_URL=https://gasprice.poa.network/
FOREIGN_GAS_PRICE_SPEED_TYPE=standard
FOREIGN_GAS_PRICE_FALLBACK=1000000000
FOREIGN_GAS_PRICE_UPDATE_INTERVAL=600000
QUEUE_URL=amqp://rabbit
REDIS_URL=redis://redis:6379
REDIS_LOCK_TTL=1000
HOME_START_BLOCK=<bridgeDeploymentResults.json / homeBridge / deployedBlockNumber>
FOREIGN_START_BLOCK=<bridgeDeploymentResults.json / foreignBridge / deployedBlockNumber>
LOG_LEVEL=info
MAX_PROCESSING_TIME=20000
3、构建并运行Bridge Oracle（使用Docker和Docker Compose）
这个Docker包由Reddit数据库、Rabbit MQ代理和Nodejs Workers组成。
$ docker-compose up --build
使用标志-d在后台运行Bridge Oracle（守护进程）
步骤5：配置和部署桥UI
最后一步是部署用户界面以在侧链和主链之间传输daibi 。
1、定位到文件夹ui
$ cd ../ui
2、在./.env中创建配置文件
注意1：打开保存的JSON文件bridgeDeploymentResults.json以获取本地和外部桥接合约地址和部署区块编号。
{
"homeBridge": {
"address": "0xc4e7cA947521f331969e41CC7c99ADa22F2C7F9C",
"deployedBlockNumber": 9044640,
"erc677": {
"address": "0xEa3acD04DdaF1F1A5Ae1B9f5f690123aA4E19B36"
}
},
"foreignBridge": {
"address": "0xeb2dbC5AB9380A3517AcA9d8CA0c39873e569a93",
"deployedBlockNumber": 4503560
}
}
REACT_APP_HOME_BRIDGE_ADDRESS=<bridgeDeploymentResults.json / homeBridge / address>
REACT_APP_FOREIGN_BRIDGE_ADDRESS=<bridgeDeploymentResults.json / foreignBridge / address>
REACT_APP_HOME_HTTP_PARITY_URL=https://sokol.poa.network
REACT_APP_FOREIGN_HTTP_PARITY_URL=https://rinkeby.infura.io/mew
3、运行网桥UI
$ npm start
打开您的Internet浏览器，使用用于部署BRT代币的帐户解锁Rinkeby网络上的Metamask，然后转到http：// localhost：3000 /
如果您在Rinkeby网络上，您应该看到您在主链（Rinkeby）上拥有100个BRT代币，在侧链（Poa Sokol）上拥有0个BR代币。
您现在可以在主链和侧链之间传输BRT代币：
—-
编译者/作者：不详
玩币族申明：玩币族作为开放的资讯翻译/分享平台，所提供的所有资讯仅代表作者个人观点，与玩币族平台立场无关，且不构成任何投资理财建议。文章版权归原作者所有。
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