HyperLedger Fabcar 學習筆記（基於超級帳本編寫第一個應用）

HyperLedger Fabcar 學習筆記（基於超級帳本編寫第一個應用）

翻譯自：http://hyperledger-fabric.rea...

編寫第一個應用程序

咱們須要實現以下三個步驟

1. 首先設置一個開發環境
2. 學習一些簡單的咱們app將會用到的智能合約的參數
3. 開發一個app可以更新查詢一個帳本

設置開發環境

1. 首先確保必備的fabric image等已經安裝成功，若是沒有安裝，請參考（https://hyperledger-fabric.re...）
2. 下載fabric-samples，而且安裝必備的運行工具。（參考地址：https://hyperledger-fabric.re...）
3. 上述步驟若是不想看英文的同窗，能夠參考（搭建第一個超級帳本網絡的方法）https://segmentfault.com/a/11...
4. 若是按照創建超級帳本網絡的教程運行，可能會啓動着一個網絡，會對接下來的流程有影響，須要關閉網絡。

   ./byfn.sh -m down

5. 進入到fabric-sample／fabcar目錄下：這是一個關於car（汽車）交易的app

   cd fabric-samples/fabcar  && ls
   顯示結果
   enrollAdmin.js     invoke.js       package.json    query.js        registerUser.js startFabric.sh

6. 殺死當前運行的全部docker 鏡像服務

   docker rm -f $(docker ps -aq)

7. 清除全部緩存網絡
   docker network prune
8. 若是已經運行過此教程，還須要執行以下操做，刪除chaincode鏡像,若是第一次運行是不會有的
   docker rmi dev-peer0.org1.example.com-fabcar-1.0-5c906e402ed29f20260ae42283216aa75549c571e2e380f3615826365d8269ba

安裝客戶端並登陸網絡

1. 首先要確保fabric-ca-client和fabric-client是否已經準備好了，這兩個module是Node.js訪問超級帳本網絡的SDK

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

   • 此時會在fabcar目錄下顯示node_module目錄以及一個package.json的文件。此部分若是不理解能夠學習node.js相關知識。
2. 經過命令建立一個超級帳本網絡

   ./startFabric.sh #運行golang編寫的chaincode

• 說明：此腳本會建立建立一個超級帳本網絡，包括ca-server peer order等節點，安裝並實例化了chaincode。
  ./startFabric.sh node#運行node.js編寫的chaincode

App如何使用網絡

建立Admin用戶

1. 首先應用的admin用戶應該向ca-server發送一個證書登記請求，接受一個對於這個user的登記證書（eCert），後續咱們會根據使用這個admin註冊和認證一個新的user。命令以下：

   node enrollAdmin.js

   命令執行成功會建立一個hfc-key-store目錄，目錄中存放admin的身份標示，一對公私密鑰。

建立普通User用戶

1. 建立一個普通用戶user1，這個用戶用來查詢和更新帳本。admin用戶身份用來建立user1用戶。執行以下命令：

   node registerUser.js

查詢帳本信息

1. 執行查詢命令查詢當前汽車信息

   node query.js

   • 會顯示所有的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. 咱們能夠嘗試修改query.js後再次運行腳本

   const request = {
   //targets : --- letting this default to the peers assigned to the channel
       chaincodeId: 'fabcar',
       fcn: 'queryCar',    //此處修改成查詢單個CAR信息
       args: ['CAR5']        //經過修改參數查詢指定的CAR信息
   };
   顯示結果以下
   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. 咱們經過查看fabric-sample／chaincode／fabcar 查看智能合約代碼，咱們的app就是調用了智能合約中支持的函數，經過rpc方式。支持函數以下：initLedger用於建立初始化的10個CAR信息

   initLedger, queryCar, queryAllCars, createCar, and changeCarOwner.

4. APP執行流程圖

更新帳本信息

1. 更新帳本信息在APP側和查詢類似，就是經過智能合約提供的接口更新數據。當前提供的功能包括建立CAR，以及修改CAR的owner屬性。咱們能夠經過修改invoke.js代碼實現對不一樣接口的調用。

   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
       };
   執行結果：
   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. 建立後查詢全部CAR信息,能夠看到增長了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. 合約執行流程如圖：

- 先經過客戶端提交交易
- 經過背書節點檢查後，客戶端獲得背書節點響應
- 客戶端將背書節點響應結果提交給order排序節點
- order節點建立區塊後，廣播給全部的peer節點更新帳本