簡介

Hyperledger fabric Client (HFC)提供了基於Node.js的應用介面來訪問Hyperledger區塊. 本文介紹了一個使用HFC訪問IBM Bluemixr區塊服務的Hello World示例程式的開發過程.

第一步 安裝HFC

在工作目錄下執行如下npm命令從安裝HFC, 由於目前IBM Bluemixr提供的Hyperledger區塊服務依舊是0.5版本， 對應的HFC版本則是0.5.x。

    npm install [email protected]

第二步 從以下連結下載IBM Bluemixr的CA證書檔案 （us.blockchain.ibm.com.cert）

    https://blockchain-certs.mybluemix.net/

示例程式原始碼

    var hfc = require('hfc');
    var fs = require('fs');

    var PEER_ADDRESS = "grpcs://e1bb641577f249a88acca04da0272249-vp3.us.blockchain.ibm.com:30304";
    var MEMBERSRVC_ADDRESS = "grpcs://e1bb641577f249a88acca04da0272249-ca.us.blockchain.ibm.com:30304";
    var ENROLL_USER_NAME="WebAppAdmin";
    var ENROLL_USER_PASSWORD="4258cc884f";
    var CHAIN_CODE_ID="e2623e76371a16ca86d97bfb90bdab95885939bf4f2fa40133d65bca4aace27eaf94d8cd10438b80de097442916f6bfef87fb45a6cd678e3cb6ec0bd8dd008c2";

    console.log(" **** starting HFC sample ****");

    var pem = fs.readFileSync('us.blockchain.ibm.com.cert'); 

    var chain = hfc.newChain("testChain");

    var keyValStorePath = "/tmp/hfc_keyValStore";

    chain.setDevMode(false);
    chain.setECDSAModeForGRPC(true);
            
    chain.setKeyValStore(hfc.newFileKeyValStore(keyValStorePath));
    chain.setMemberServicesUrl(MEMBERSRVC_ADDRESS, {pem:pem});
    chain.addPeer(PEER_ADDRESS, {pem:pem});

    chain.enroll(ENROLL_USER_NAME, ENROLL_USER_PASSWORD, function (err, user) {
        if (err) {
            console.log("ERROR: failed to register user: %s",err);
            process.exit(1);
        }
                
        console.log("**** Enrolled ****");
        
        console.log("querying chaincode ...");
    
        var queryRequest = {
        chaincodeID: CHAIN_CODE_ID,
            fcn: "query",
            args: [""]
        };
        
        // Issue the query request and listen for events
        var tx = user.query(queryRequest);
    
        tx.on('complete', function (results) {
            
            console.log("query completed successfully; results=%j",results);
            console.log(results.result.toString());
            process.exit(0);
        });
        tx.on('error', function (error) {
            console.log("Failed to query chaincode: request=%j, error=%k",queryRequest,error);
            process.exit(1);
        });
    });
 

執行結果

    C:\work\HFC>node test.js
    **** starting HFC sample ****
    **** Enrolled ****
    querying chaincode ...
    query completed successfully; results={"result":{"type":"Buffer","data":[72,101,108,108,111,32,87,111,114,108,100]}}
    Hello World

後記

• 使用npm安裝HFC會呼叫git命令從github下載相關原始檔，如果使用代理伺服器的話，使用以下命令配置git
  。

    git config --global http.proxy <proxy server host>:<proxy server port>

• 安裝HFC時報錯： MSBUILD error MSB3428: Could not load the Visual C++ component "VCBuild.exe"

    MSBUILD : error MSB3428: Could not load the Visual C++ component "VCBuild.exe". To fix this, 1) install the .NET Framework 2.0 SDK, 2) install Microsoft Visual Studio 2005 or 3) add the location of the component to the system path if it is installed elsewhere. 

首先安裝Visual C++ Build Tools 2015

然後執行以下命令

    npm config set msvs_version 2015 --global

再次安裝HFC

• 安裝HFC時報錯：

    win_delay_load_hook.c(31): error C2373: '__pfnDliNotifyHook2': redefinition; different type modifiers

執行以下命令後再次安裝HFC

     npm -g install [email protected]

• 註冊使用者時報錯：

    E1105 15:46:35.785000000  6360 handshake.c:215] Read failed.
    E1105 15:46:35.785000000  6360 secure_channel_create.c:102] Secure handshake failed with error 1.

新增如下程式碼

    chain.setECDSAModeForGRPC(true);

• 註冊使用者時報錯：

    hfc [MemberServicesImpl.enroll] failed to create cert pair: err={"code":12,"metadata":{"_internal_repr":{}}} +992ms
    hfc [memberServices.enroll] err=Error: unknown service protos.ECAP, enrollment=undefined +1ms
    ERROR: failed to register admin: Error: unknown service protos.ECAP

檢查確認MEMBERSRVC_ADDRESS指向CA服務

總結

本文介紹了一個基於Hyperledger fabric Client(HFC)的Hello World示例程式。