30分钟极速编程：Hyperledger Fabric 2.2入门

AryaXia
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概述

本文介绍如何设置Hyperledger Fabric Network（HLF）v2.2、部署链码、调用和查询链码。我们首先给予了一个高层次的过程演练，然后使用HLF示例中提供的测试网络来演示整个过程。Test Network中提供的脚本使得区块链网络和Fabric CA服务器的设置变得更加容易。

基本步骤

  1. 使用Fabric CA服务器从组织和订购者（Org1、Org2和订购者）生成crypto-material。
  2. 产生通道相关组件，例如系统通道块、通道事务、通道创世块等）。
  3. 创建peer anchor。
  4. 创建通道。
  5. 加入通道。
  6. 在通道中部署chaincode。
  7. 调用或查询链码。

所需软件环境

  1. Golang
  2. Docker
  3. Nodejs

构建网络

在这里，我们首先下载HLF，使用其提供的测试网络。我们的网络将由两个组织（每个组织一个peer）、一个orderer节点、三个CA服务器（每个组织一个，以及orderer一个）、两个状态数据库couchdb实例（每个peer一个）组成。

1.下载fabric并安装相关镜像。

curl -sSL https://bit.ly/2ysbOFE | bash -s -- 2.3.0 1.4.9

2.设置环境变量

cd fabric-samples && export PATH=$PWD/bin:$PATH

3.完成步骤2后，转到test-network文件夹。

cd test-network

4.可以运行命令检查所有可用选项： ./network.sh help

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5.使用Fabric CA服务器、CouchDB启动网络并创建通道 mychannel。

  • -ca：使用证书颁发机构生成网络加密材料
  • -c ：要创建的频道名称（默认为“mychannel”）
  • -s ：要部署的对等状态数据库：goleveldb（默认）或couchdb
  • up -显示结构订购者和对等节点。未创建通道。
  • up createChannel：启动具有一个通道的结构网络。
  • createChannel ：在网络创建后创建并加入频道

./network.sh up createChannel -ca -c mychannel -s couchdb

如果一切顺利的话，最后你会看到这样的画面。

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6.下一步部署chaincode。注意：在示例中有多个chaincode。

  • -ccn：链代码名称。此标志可用于将其中一个资产传输样本部署到通道。示例选项：basic (default), ledger, private, sbe, secured
  • -ccl： 要部署的链码的编程语言：go (default), java, javascript, typescript
  • -verbose：Verbose模式

./network.sh deployCC -ccn basic -ccp ../asset-transfer-basic/chaincode-javascript/ -ccl javascript -verbose

一旦chaincode部署成功，您将获得如下输出

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7.现在，链码部署已经完成，我们将调用和查询链码。我们将使用nodejs SDK与区块链网络进行交互。

cd ../asset-transfer-basic/application-javascript && npm install

node app.js

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此脚本将用户 appUser 注册到FileSystemWallet中，并将调用 InitLedger 函数，该函数将在分类账中创建6条记录。在此之后，它调用函数 GetAllAssets *并且此函数返回分类帐中存储的所有记录，之后调用 CreateAsset这将在分类账中添加新记录。

具体代码如下：

 * Copyright IBM Corp. All Rights Reserved.
 *
 * SPDX-License-Identifier: Apache-2.0
 */

'use strict';

const { Gateway, Wallets } = require('fabric-network');
const FabricCAServices = require('fabric-ca-client');
const path = require('path');
const { buildCAClient, registerAndEnrollUser, enrollAdmin } = require('../../test-application/javascript/CAUtil.js');
const { buildCCPOrg1, buildWallet } = require('../../test-application/javascript/AppUtil.js');

const channelName = 'mychannel';
const chaincodeName = 'basic';
const mspOrg1 = 'Org1MSP';
const walletPath = path.join(__dirname, 'wallet');
const org1UserId = 'appUser';

function prettyJSONString(inputString) {
	return JSON.stringify(JSON.parse(inputString), null, 2);
}

// pre-requisites:
// - fabric-sample two organization test-network setup with two peers, ordering service,
//   and 2 certificate authorities
//         ===> from directory /fabric-samples/test-network
//         ./network.sh up createChannel -ca
// - Use any of the asset-transfer-basic chaincodes deployed on the channel "mychannel"
//   with the chaincode name of "basic". The following deploy command will package,
//   install, approve, and commit the javascript chaincode, all the actions it takes
//   to deploy a chaincode to a channel.
//         ===> from directory /fabric-samples/test-network
//         ./network.sh deployCC -ccn basic -ccp ../asset-transfer-basic/chaincode-javascript/ -ccl javascript
// - Be sure that node.js is installed
//         ===> from directory /fabric-samples/asset-transfer-basic/application-javascript
//         node -v
// - npm installed code dependencies
//         ===> from directory /fabric-samples/asset-transfer-basic/application-javascript
//         npm install
// - to run this test application
//         ===> from directory /fabric-samples/asset-transfer-basic/application-javascript
//         node app.js

// NOTE: If you see  kind an error like these:
/*
    2020-08-07T20:23:17.590Z - error: [DiscoveryService]: send[mychannel] - Channel:mychannel received discovery error:access denied
    ******** FAILED to run the application: Error: DiscoveryService: mychannel error: access denied

   OR

   Failed to register user : Error: fabric-ca request register failed with errors [[ { code: 20, message: 'Authentication failure' } ]]
   ******** FAILED to run the application: Error: Identity not found in wallet: appUser
*/
// Delete the /fabric-samples/asset-transfer-basic/application-javascript/wallet directory
// and retry this application.
//
// The certificate authority must have been restarted and the saved certificates for the
// admin and application user are not valid. Deleting the wallet store will force these to be reset
// with the new certificate authority.
//

/**
 *  A test application to show basic queries operations with any of the asset-transfer-basic chaincodes
 *   -- How to submit a transaction
 *   -- How to query and check the results
 *
 * To see the SDK workings, try setting the logging to show on the console before running
 *        export HFC_LOGGING='{"debug":"console"}'
 */
async function main() {
	try {
		// build an in memory object with the network configuration (also known as a connection profile)
		const ccp = buildCCPOrg1();

		// build an instance of the fabric ca services client based on
		// the information in the network configuration
		const caClient = buildCAClient(FabricCAServices, ccp, 'ca.org1.example.com');

		// setup the wallet to hold the credentials of the application user
		const wallet = await buildWallet(Wallets, walletPath);

		// in a real application this would be done on an administrative flow, and only once
		await enrollAdmin(caClient, wallet, mspOrg1);

		// in a real application this would be done only when a new user was required to be added
		// and would be part of an administrative flow
		await registerAndEnrollUser(caClient, wallet, mspOrg1, org1UserId, 'org1.department1');

		// Create a new gateway instance for interacting with the fabric network.
		// In a real application this would be done as the backend server session is setup for
		// a user that has been verified.
		const gateway = new Gateway();

		try {
			// setup the gateway instance
			// The user will now be able to create connections to the fabric network and be able to
			// submit transactions and query. All transactions submitted by this gateway will be
			// signed by this user using the credentials stored in the wallet.
			await gateway.connect(ccp, {
				wallet,
				identity: org1UserId,
				discovery: { enabled: true, asLocalhost: true } // using asLocalhost as this gateway is using a fabric network deployed locally
			});

			// Build a network instance based on the channel where the smart contract is deployed
			const network = await gateway.getNetwork(channelName);

			// Get the contract from the network.
			const contract = network.getContract(chaincodeName);

			// Initialize a set of asset data on the channel using the chaincode 'InitLedger' function.
			// This type of transaction would only be run once by an application the first time it was started after it
			// deployed the first time. Any updates to the chaincode deployed later would likely not need to run
			// an "init" type function.
			console.log('\n--> Submit Transaction: InitLedger, function creates the initial set of assets on the ledger');
			await contract.submitTransaction('InitLedger');
			console.log('*** Result: committed');

			// Let's try a query type operation (function).
			// This will be sent to just one peer and the results will be shown.
			console.log('\n--> Evaluate Transaction: GetAllAssets, function returns all the current assets on the ledger');
			let result = await contract.evaluateTransaction('GetAllAssets');
			console.log(`*** Result: ${prettyJSONString(result.toString())}`);

			// Now let's try to submit a transaction.
			// This will be sent to both peers and if both peers endorse the transaction, the endorsed proposal will be sent
			// to the orderer to be committed by each of the peer's to the channel ledger.
			console.log('\n--> Submit Transaction: CreateAsset, creates new asset with ID, color, owner, size, and appraisedValue arguments');
			result = await contract.submitTransaction('CreateAsset', 'asset13', 'yellow', '5', 'Tom', '1300');
			console.log('*** Result: committed');
			if (`${result}` !== '') {
				console.log(`*** Result: ${prettyJSONString(result.toString())}`);
			}

			console.log('\n--> Evaluate Transaction: ReadAsset, function returns an asset with a given assetID');
			result = await contract.evaluateTransaction('ReadAsset', 'asset13');
			console.log(`*** Result: ${prettyJSONString(result.toString())}`);

			console.log('\n--> Evaluate Transaction: AssetExists, function returns "true" if an asset with given assetID exist');
			result = await contract.evaluateTransaction('AssetExists', 'asset1');
			console.log(`*** Result: ${prettyJSONString(result.toString())}`);

			console.log('\n--> Submit Transaction: UpdateAsset asset1, change the appraisedValue to 350');
			await contract.submitTransaction('UpdateAsset', 'asset1', 'blue', '5', 'Tomoko', '350');
			console.log('*** Result: committed');

			console.log('\n--> Evaluate Transaction: ReadAsset, function returns "asset1" attributes');
			result = await contract.evaluateTransaction('ReadAsset', 'asset1');
			console.log(`*** Result: ${prettyJSONString(result.toString())}`);

			try {
				// How about we try a transactions where the executing chaincode throws an error
				// Notice how the submitTransaction will throw an error containing the error thrown by the chaincode
				console.log('\n--> Submit Transaction: UpdateAsset asset70, asset70 does not exist and should return an error');
				await contract.submitTransaction('UpdateAsset', 'asset70', 'blue', '5', 'Tomoko', '300');
				console.log('******** FAILED to return an error');
			} catch (error) {
				console.log(`*** Successfully caught the error: \n    ${error}`);
			}

			console.log('\n--> Submit Transaction: TransferAsset asset1, transfer to new owner of Tom');
			await contract.submitTransaction('TransferAsset', 'asset1', 'Tom');
			console.log('*** Result: committed');

			console.log('\n--> Evaluate Transaction: ReadAsset, function returns "asset1" attributes');
			result = await contract.evaluateTransaction('ReadAsset', 'asset1');
			console.log(`*** Result: ${prettyJSONString(result.toString())}`);
		} finally {
			// Disconnect from the gateway when the application is closing
			// This will close all connections to the network
			gateway.disconnect();
		}
	} catch (error) {
		console.error(`******** FAILED to run the application: ${error}`);
	}
}

main();

我们可以通过fauxton UI来查询结果。

peer0.org1：http://localhost:7984/_utils/#

peer0.org2: http://localhost:7984/_utils/#

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