HyperLedger Fabcar 学习笔记（基于超级账本编写第一个应用）

翻译自：http://hyperledger-fabric.rea...

编写第一个应用程序

我们需要实现如下三个步骤

1. 首先设置一个开发环境
2. 学习一些简单的我们app将会用到的智能合约的参数
3. 开发一个app能够更新查询一个账本

设置开发环境

1. 首先确保必备的fabric image等已经安装成功，如果没有安装，请参考（https://hyperledger-fabric.re...）
2. 下载fabric-samples，并且安装必备的运行工具。（参考地址：https://hyperledger-fabric.re...）
3. 上述步骤如果不想看英文的同学，可以参考（搭建第一个超级账本网络的方法）https://segmentfault.com/a/11...
4. 如果按照建立超级账本网络的教程运行，可能会启动着一个网络，会对接下来的流程有影响，需要关闭网络。

   ./byfn.sh -m down

5. 进入到fabric-sample／fabcar目录下：这是一个关于car（汽车）交易的app

   cd fabric-samples/fabcar  && ls
   显示结果
   enrollAdmin.js     invoke.js       package.json    query.js        registerUser.js startFabric.sh

6. 杀死当前运行的所有docker 镜像服务

   docker rm -f $(docker ps -aq)

7. 清除所有缓存网络
   docker network prune
8. 如果已经运行过此教程，还需要执行如下操作，删除chaincode镜像,如果第一次运行是不会有的
   docker rmi dev-peer0.org1.example.com-fabcar-1.0-5c906e402ed29f20260ae42283216aa75549c571e2e380f3615826365d8269ba

安装客户端并登录网络

1. 首先要确保fabric-ca-client和fabric-client是否已经准备好了，这两个module是Node.js访问超级账本网络的SDK

   npm install fabric-client
npm install fabric-ca-client

   • 此时会在fabcar目录下显示node_module目录以及一个package.json的文件。此部分如果不理解可以学习node.js相关知识。
2. 通过命令创建一个超级账本网络

   ./startFabric.sh #运行golang编写的chaincode

• 说明：此脚本会创建创建一个超级账本网络，包括ca-server peer order等节点，安装并实例化了chaincode。
  ./startFabric.sh node#运行node.js编写的chaincode

App如何使用网络

创建Admin用户

1. 首先应用的admin用户应该向ca-server发送一个证书登记请求，接受一个对于这个user的登记证书（eCert），后续我们会根据使用这个admin注册和认证一个新的user。命令如下：

   node enrollAdmin.js

   命令执行成功会创建一个hfc-key-store目录，目录中存放admin的身份标示，一对公私密钥。

创建普通User用户

1. 创建一个普通用户user1，这个用户用来查询和更新账本。admin用户身份用来创建user1用户。执行如下命令：

   node registerUser.js

查询账本信息

1. 执行查询命令查询当前汽车信息

   node query.js

   • 会显示全部的CAR信息CAR0-CAR9

   [{"Key":"CAR0", "Record":    {"colour":"blue","make":"Toyota","model":"Prius","owner":"Tomoko"}},{"Key":"CAR1", "Record":{"colour":"red","make":"Ford","model":"Mustang","owner":"Brad"}},{"Key":"CAR2", "Record":{"colour":"green","make":"Hyundai","model":"Tucson","owner":"Jin Soo"}},{"Key":"CAR3", "Record":{"colour":"yellow","make":"Volkswagen","model":"Passat","owner":"Max"}},{"Key":"CAR4", "Record":{"colour":"black","make":"Tesla","model":"S","owner":"Adriana"}},{"Key":"CAR5", "Record":{"colour":"purple","make":"Peugeot","model":"205","owner":"Michel"}},{"Key":"CAR6", "Record":{"colour":"white","make":"Chery","model":"S22L","owner":"Aarav"}},{"Key":"CAR7", "Record":{"colour":"violet","make":"Fiat","model":"Punto","owner":"Pari"}},{"Key":"CAR8", "Record":{"colour":"indigo","make":"Tata","model":"Nano","owner":"Valeria"}},{"Key":"CAR9",     "Record":{"colour":"brown","make":"Holden","model":"Barina","owner":"Shotaro"}}]

2. 我们可以尝试修改query.js后再次运行脚本

   const request = {
   //targets : --- letting this default to the peers assigned to the channel
       chaincodeId: 'fabcar',
       fcn: 'queryCar',    //此处修改为查询单个CAR信息
       args: ['CAR5']        //通过修改参数查询指定的CAR信息
   };
   显示结果如下
   Store path:/Users/ly/go/src/github.com/hyperledger/fabric-samples/fabcar/hfc-key-store
   Successfully loaded user1 from persistence
   Query has completed, checking results
   Response is  {"colour":"purple","make":"Peugeot","model":"205","owner":"Michel"}

3. 我们通过查看fabric-sample／chaincode／fabcar 查看智能合约代码，我们的app就是调用了智能合约中支持的函数，通过rpc方式。支持函数如下：initLedger用于创建初始化的10个CAR信息

   initLedger, queryCar, queryAllCars, createCar, and changeCarOwner.

4. APP执行流程图

更新账本信息

1. 更新账本信息在APP侧和查询相似，就是通过智能合约提供的接口更新数据。当前提供的功能包括创建CAR，以及修改CAR的owner属性。我们可以通过修改invoke.js代码实现对不同接口的调用。

   var request = {
           //targets: let default to the peer assigned to the client
           chaincodeId: 'fabcar',
           fcn: 'createCar',
           args: ['CAR12', 'Honda', 'Accord', 'Black', 'Tom'],
           chainId: 'mychannel',
           txId: tx_id
       };
   执行结果：
   lydeiMac:fabcar ly$ node invoke.js 
   Store path:/Users/ly/go/src/github.com/hyperledger/fabric-samples/fabcar/hfc-key-store
   Successfully loaded user1 from persistence
   Assigning transaction_id:  a5b684603b1f2a0296851409cecb143c3109220014182721165ef8fe5c326b2e
   Transaction proposal was good
   Successfully sent Proposal and received ProposalResponse: Status - 200, message - "OK"
   The transaction has been committed on peer localhost:7053
   Send transaction promise and event listener promise have completed
   Successfully sent transaction to the orderer.
   Successfully committed the change to the ledger by the peer

2. 创建后查询所有CAR信息,可以看到增加了CAR12信息

   [{"Key":"CAR0", "Record":{"colour":"blue","make":"Toyota","model":"Prius","owner":"Tomoko"}},{"Key":"CAR1", "Record":{"colour":"red","make":"Ford","model":"Mustang","owner":"Brad"}},{"Key":"CAR12", "Record":{"colour":"Black","make":"Honda","model":"Accord","owner":"Tom"}},{"Key":"CAR2", "Record":{"colour":"green","make":"Hyundai","model":"Tucson","owner":"Jin Soo"}},{"Key":"CAR3", "Record":{"colour":"yellow","make":"Volkswagen","model":"Passat","owner":"Max"}},{"Key":"CAR4", "Record":{"colour":"black","make":"Tesla","model":"S","owner":"Adriana"}},{"Key":"CAR5", "Record":{"colour":"purple","make":"Peugeot","model":"205","owner":"Michel"}},{"Key":"CAR6", "Record":{"colour":"white","make":"Chery","model":"S22L","owner":"Aarav"}},{"Key":"CAR7", "Record":{"colour":"violet","make":"Fiat","model":"Punto","owner":"Pari"}},{"Key":"CAR8", "Record":{"colour":"indigo","make":"Tata","model":"Nano","owner":"Valeria"}},{"Key":"CAR9", "Record":{"colour":"brown","make":"Holden","model":"Barina","owner":"Shotaro"}}]

3. 合约执行流程如图：

- 先通过客户端提交交易
- 通过背书节点检查后，客户端得到背书节点响应
- 客户端将背书节点响应结果提交给order排序节点
- order节点创建区块后，广播给所有的peer节点更新账本

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