区块链导论:以太坊(Ethereum)

以太坊(Ethereum)是一个开源的有智能合约功能的公共区块链平台。通过其专用加密货币以太币(Ether)提供去中心化的虚拟机(“以太虚拟机” Ethereum Virtual Machine)来处理点对点合约。

关于以太坊(Ethereum)的概念网上有很多资料可以查询,本文只上干货,主要目的如下:

  1. 搭建Ethereum的开发环境
  2. 熟悉Ethereum DAPP开发框架:Truffle
  3. Truffle DAPP开发和调试

以太坊开发环境搭建

安装区块链仿真环境(ganache)、solidity编译器web3truffle

1
npm install -g ganache-cli solc web3 truffle

IDE

  • Atom

安装linter-solidity插件。

1
2
$ apm install linter
$ apm install linter-solidity
  • ethereum客户端
    这里使用Metamask,下载对应的浏览器版本,安装到浏览器的插件里。

选择Custom RPC加入本地ganche私有链-“http://127.0.0.1:7545"。

开启环境

  • 开启仿真环境ganache

  • metamask连接私有链
    Customer Rpc -> http://127.0.0.1:7545

Truffle

Truffle是一个世界级的开发环境,测试框架,以太坊的资源管理通道,致力于让以太坊上的开发变得简单,Truffle有以下功能:

  • 内置的智能合约编译,链接,部署和二进制文件的管理。
  • 快速开发下的自动合约测试。
  • 脚本化的,可扩展的部署与发布框架。
  • 部署到不管多少的公网或私网的网络环境管理功能
  • 使用EthPM&NPM提供的包管理,使用ERC190标准。
  • 与合约直接通信的直接交互控制台(写完合约就可以命令行里验证了)。
  • 可配的构建流程,支持紧密集成。
  • 在Truffle环境里支持执行外部的脚本。

Truffle 开发部署合约

  1. 创建工程
1
2
3
mkdir fibonacci
cd fibonacci
truffle init

工程目录结构如下:
app/ - 你的应用文件运行的默认目录。这里面包括推荐的javascript文件和css样式文件目录,但你可以完全决定如何使用这些目录。
contract/ - Truffle默认的合约文件存放地址。
migrations/ - 存放发布脚本文件
test/ - 用来测试应用和合约的测试文件
truffle.js - Truffle的配置文件

  1. 编写一个基础智能合约

创建一个合约contracts/Fibonacci.sol:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
pragma solidity ^0.4.22;
contract Fibonacci {
uint[] fibseries;
// n = how many in the series to return
function generateFib(uint n) public {
// set 1st and 2nd entries
fibseries.push(1);
fibseries.push(1);
// generate subsequent entries
for (uint i=2; i < n ; i++) {
fibseries.push(fibseries[i-1] + fibseries[i-2]);
}
}
}

generateFib:生成Fibonacci(斐波纳契)数列,公式fib(n)=fib(n-1)+fib(n-2)

  1. 创建一个新的部署文件migrations/2_deploy_contracts.js
1
2
3
4
5
var Fibonacci = artifacts.require("Fibonacci");
module.exports = function(deployer) {
deployer.deploy(Fibonacci);
};
  1. 启动Ganache

  2. 修改工程目录下的truffle.js

1
2
3
4
5
6
7
8
9
module.exports = {
networks: {
development: {
host: "127.0.0.1",
port: 7545,
network_id: "*"
}
}
};
  1. 编译并植入合约
    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    truffle compile
    truffle migrate
    Using network 'development'.
    Running migration: 1_initial_migration.js
    Deploying Migrations...
    ... 0x97f35c60501091e10315febe0d2f1d8a59cb413c38cc7c2b3538263a7c67d0bf
    Migrations: 0xf7f433a4a2f9bf3f364bb96abe6a07778a61e095
    Saving successful migration to network...
    ... 0x17b700e3a580ddd28d7bb7110c33f5a8c94b8875c99138d466f8625056a47cd9
    Saving artifacts...
    Running migration: 2_deploy_contracts.js
    Deploying Fibonacci...
    ... 0xd1f02be04a76df173456b48777d740f65248cd5870c4e22c058cc6f658dc2f9e
    Fibonacci: 0xc9554c5818dac7e79dc398d85c4789b90618c5b7
    Saving successful migration to network...
    ... 0xb987be952d829ca21a909e2f558abdae84cf6afe0c83c2070ab2ba8319f79672
    Saving artifacts...

console debug

我们可以直接使用remix ide,调试非常的方便。
这里我们虐一下自己,使用Truffle Console来进行调试。

  1. 进入console

    truffle console

  2. 调用合约

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    truffle(development)> Fibonacci.deployed().then(function(instance){return instance.generateFib(10);});
    { tx: '0x0d10a3f875548131fdad0a27f916af5575fcf6ee47085e9d625d695eb2c11583',
    receipt:
    { transactionHash: '0x0d10a3f875548131fdad0a27f916af5575fcf6ee47085e9d625d695eb2c11583',
    transactionIndex: 0,
    blockHash: '0x7596a7239811b8586a2c60a9fad19d41ea8bb3be46e8ed3b8ebbfaf4c477b707',
    blockNumber: 5,
    gasUsed: 298373,
    cumulativeGasUsed: 298373,
    contractAddress: null,
    logs: [],
    status: '0x01',
    logsBloom: '0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000' },
    logs: [] }
  3. 调试transaction

    1. 先attache一条transaction,id为transactionHash值。

      1
      2
      3
      4
      5
      6
      7
      8
      9
      10
      11
      12
      13
      14
      15
      16
      17
      truffle(development)> debug 0x0d10a3f875548131fdad0a27f916af5575fcf6ee47085e9d625d695eb2c11583
      Compiling ./contracts/Fibonacci.sol...
      Compiling ./contracts/Migrations.sol...
      Gathering transaction data...
      Addresses affected:
      0xc9554c5818dac7e79dc398d85c4789b90618c5b7 - Fibonacci
      Commands:
      (enter) last command entered (step next)
      (o) step over, (i) step into, (u) step out, (n) step next
      (;) step instruction, (p) print instruction, (h) print this help, (q) quit
      (b) toggle breakpoint, (c) continue until breakpoint
      (+) add watch expression (`+:<expr>`), (-) remove watch expression (-:<expr>)
      (?) list existing watch expressions
      (v) print variables and values, (:) evaluate expression - see `v`

      Commands即为调试命令行。

    2. watch(+:)变量,按n逐行进行跟踪。

      1
      2
      3
      4
      5
      6
      7
      8
      9
      10
      11
      12
      13
      14
      15
      16
      17
      18
      debug(development:0x0d10a3f8...)> +:i
      8
      debug(development:0x0d10a3f8...)> +:fibseries
      [ 1, 1, 2, 3, 5, 8, 13, 21 ]
      debug(development:0x0d10a3f8...)> n
      Fibonacci.sol:
      14: // generate subsequent entries
      15: for (uint i=2; i < n ; i++) {
      16: fibseries.push(fibseries[i-1] + fibseries[i-2]);
      ^
      :i
      8
      :fibseries
      [ 1, 1, 2, 3, 5, 8, 13, 21 ]
  4. 异常信息调试

    1. 修改以下合约代码

      1
      2
      3
      ...
      for (uint i=1; i < n ; i++) {
      ...
    2. 重新编译部署合约

      1
      2
      3
      4
      5
      6
      7
      8
      9
      10
      11
      12
      13
      14
      15
      16
      17
      18
      19
      20
      21
      22
      23
      24
      25
      26
      27
      28
      29
      30
      31
      32
      debug(development:0x65bb45af...)> compile --all
      Transaction completed successfully.
      truffle(development)> migrate --reset
      Compiling ./contracts/Fibonacci.sol...
      Writing artifacts to ./build/contracts
      Using network 'development'.
      Running migration: 1_initial_migration.js
      Replacing Migrations...
      ... 0x26fdc5c20b9f44e96e537e0b8474f867d7bd7d27ad7172b004c858d2dceb6f99
      Migrations: 0xd0ea55247c6035375c6e284a60946cd35550ced2
      Saving successful migration to network...
      ... 0x0ad76d3073b05161327fc1f7dbd1c521360c305af872ff12b7f59befb73dfbd2
      Saving artifacts...
      Running migration: 2_deploy_contracts.js
      Replacing Fibonacci...
      ... 0x93ee91146a3a5fd23dad1e77249870c0edeb5cf6cd78cb7c9db6aab24f538634
      Fibonacci: 0x090b1fd13ee19ec7f8f3175ca54d5165a443c694
      Saving successful migration to network...
      ... 0xbeb0d613fa72c67ecf720833a4985244a91b0d0dea1c36fc23195e00e7fd8c18
      Saving artifacts...
      truffle(development)> Fibonacci.deployed().then(function(instance){return instance.generateFib(10);});
      Error: VM Exception while processing transaction: invalid opcode
      at XMLHttpRequest._onHttpResponseEnd (/home/lizorn/.nvm/versions/node/v10.0.0/lib/node_modules/truffle/build/webpack:/~/xhr2/lib/xhr2.js:509:1)
      at XMLHttpRequest._setReadyState (/home/lizorn/.nvm/versions/node/v10.0.0/lib/node_modules/truffle/build/webpack:/~/xhr2/lib/xhr2.js:354:1)
      at XMLHttpRequestEventTarget.dispatchEvent (/home/lizorn/.nvm/versions/node/v10.0.0/lib/node_modules/truffle/build/webpack:/~/xhr2/lib/xhr2.js:64:1)
      at XMLHttpRequest.request.onreadystatechange (/home/lizorn/.nvm/versions/node/v10.0.0/lib/node_modules/truffle/build/webpack:/~/web3/lib/web3/httpprovider.js:128:1)
      at /home/lizorn/.nvm/versions/node/v10.0.0/lib/node_modules/truffle/build/webpack:/~/truffle-provider/wrapper.js:134:1
      at /home/lizorn/.nvm/versions/node/v10.0.0/lib/node_modules/truffle/build/webpack:/~/web3/lib/web3/requestmanager.js:86:1
      at Object.InvalidResponse (/home/lizorn/.nvm/versions/node/v10.0.0/lib/node_modules/truffle/build/webpack:/~/web3/lib/web3/errors.js:38:1)
    3. 此处由于数组越界,控制窗口并没有返回transaction的ID,我们可以通过查看GanacheLogs,找到对应的Transaction,然后按之前的方式进行调试。