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

這是一個建立於 的文章，其中的資訊可能已經有所發展或是發生改變。

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

翻譯自：http://hyperledger-fabric.rea...

編寫第一個應用程式

我們需要實現如下三個步驟

1. 首先設定一個開發環境
2. 學習一些簡單的我們app將會用到的智能合約的參數
3. 開發一個app能夠更新查詢一個賬本

設定開發環境

1. 首先確保必備的fabric image等已經安裝成功，如果沒有安裝，請參考（https://hyperledger-fabric.re...）
2. 下載fabric-samples，並且安裝必備的運行工具。（參考地址：https://hyperledger-fabric.re...）
3. 上述步驟如果不想看英文的同學，可以參考（搭建第一個超級賬本網路的方法）https://segmentfault.com/a/11...
4. 如果按照建立超級賬本網路的教程運行，可能會啟動著一個網路，會對接下來的流程有影響，需要關閉網路。

./byfn.sh -m down

1. 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

1. 殺死當前啟動並執行所有docker 鏡像服務

docker rm -f $(docker ps -aq)

1. 清除所有緩衝網路

docker network prune

1. 如果已經運行過此教程，還需要執行如下操作，刪除chaincode鏡像,如果第一次運行是不會有的

docker rmi dev-peer0.org1.example.com-fabcar-1.0-5c906e402ed29f20260ae42283216aa75549c571e2e380f3615826365d8269ba

安裝用戶端並登入網路

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訪問超級賬本網路的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的檔案。此部分如果不理解可以學習node.js相關知識。

1. 通過命令建立一個超級賬本網路

<!--運行golang編寫的chaincode-->
./startFabric.sh
說明：此指令碼會建立建立一個超級賬本網路，包括ca-server peer order等節點，安裝並執行個體化了chaincode。
<!--運行node.js編寫的chaincode-->
./startFabric.sh node

App如何使用網路

建立Admin使用者

1. 首先應用的admin使用者應該向ca-server發送一個認證登記請求，接受一個對於這個user的登記認證（eCert），後續我們會根據使用這個admin註冊和認證一個新的user。命令如下：

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使用者

1. 建立一個普通使用者user1，這個使用者用來查詢和更新賬本。admin使用者身份用來建立user1使用者。執行如下命令：

node registerUser.js

查詢賬本資訊

1. 執行查詢命令查詢當前汽車資訊

node query.js

• 會顯示全部的CAR資訊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"}}]

1. 我們可以嘗試修改query.js後再次運行指令碼

const request = {  //targets : --- letting this default to the peers assigned to the channel  chaincodeId: 'fabcar',  fcn: 'queryCar',    //此處修改為查詢單個CAR資訊  args: ['CAR5']        //通過修改參數查詢指定的CAR資訊};顯示結果如下Store path:/Users/ly/go/src/github.com/hyperledger/fabric-samples/fabcar/hfc-key-storeSuccessfully loaded user1 from persistenceQuery has completed, checking resultsResponse is  {"colour":"purple","make":"Peugeot","model":"205","owner":"Michel"}

1. 我們通過查看fabric-sample／chaincode／fabcar 查看智能合約代碼，我們的app就是調用了智能合約中支援的函數，通過rpc方式。支援函數如下：initLedger用於建立初始化的10個CAR資訊

initLedger, queryCar, queryAllCars, createCar, and changeCarOwner.

1. APP執行流程圖

更新賬本資訊

1. 更新賬本資訊在APP側和查詢相似，就是通過智能合約提供的介面更新資料。當前提供的功能包括建立CAR，以及修改CAR的owner屬性。我們可以通過修改invoke.js代碼實現對不同介面的調用。

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-storeSuccessfully loaded user1 from persistenceAssigning transaction_id:  a5b684603b1f2a0296851409cecb143c3109220014182721165ef8fe5c326b2eTransaction proposal was goodSuccessfully sent Proposal and received ProposalResponse: Status - 200, message - "OK"The transaction has been committed on peer localhost:7053Send transaction promise and event listener promise have completedSuccessfully sent transaction to the orderer.Successfully committed the change to the ledger by the peer

1. 建立後查詢所有CAR資訊,可以看到增加了CAR12資訊

[{"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"}}]

1. 合約執行流程

- 先通過用戶端提交交易- 通過背書節點檢查後，用戶端得到背書節點響應- 用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，廣播給所有的peer節點更新賬本