如何利用Hyperledger Fabric的SDK来开发REST API服务器

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1、系统结构概述

整个系统包含两个物理节点：

• Fabric节点：运行Fabric示例中的First Network，并且实例化了Fabcar链码

• API服务器节点：运行REST API Server代码供外部访问

下面是部署在AWS上的两个节点实例的情况：

首先参考官方文档安装hyperledger fabric。

然后运行脚本fabcar/startFabric.sh：

cd fabric-samples/fabcar./startFabric.sh

上述脚本运行之后，我们就得到一个正常运转的Hyperledger Fabric网络（著名的演示网络First Network），包含2个机构/4个对等节点，通道为mychannel，链码Fabcar安装在全部4个对等节点上并且在mychannel上激活。账本中有10条车辆记录，这是调用合约的initLedger方法的结果。

现在我们为REST API Server准备身份标识数据。使用fabcar/javascript创建一个用户标识user1，我们将在REST API Server中使用这个身份标识：

cd javascriptnpm installnode enrollAdmin.jsnode registerUser.jsls wallet/user1

运行结果如下：

现在Rest API Server需要的东西都备齐了：

• org1的连接配置文件：first-network/connection-org1.json

• Node.js包文件：fabcar/package.json

• User1身份钱包：fabcar/javascript/wallet/user1/

后面我们会把这些数据文件拷贝到Rest API Server。

2、Rest API Server设计

我们使用ExressJS来开发API服务，利用query.js和invoke.js中的代码实现与fabric交互的逻辑。API设计如下：

• GET /api/queryallcars：返回全部车辆记录

• GET /api/query/CarID：返回指定ID的车辆记录

• POST /api/addcar/：添加一条新的车辆记录

• PUT /api/changeowner/CarID：修改指定ID的车辆记录

3、Rest API Server代码实现

apiserver.js代码如下：

var bodyParser = require('body-parser');var app = express();app.use(bodyParser.json());// Setting for Hyperledger Fabricconst { FileSystemWallet, Gateway } = require('fabric-network');const path = require('path');const ccpPath = path.resolve(__dirname, '.',  'connection-org1.json');app.get('/api/queryallcars', async function (req, res) {    try {        // Create a new file system based wallet for managing identities.        const walletPath = path.join(process.cwd(), 'wallet');        const wallet = new FileSystemWallet(walletPath);        console.log(`Wallet path: ${walletPath}`);        // Check to see if we've already enrolled the user.        const userExists = await wallet.exists('user1');        if (!userExists) {            console.log('An identity for the user "user1" does not exist in the wallet');            console.log('Run the registerUser.js application before retrying');            return;        }        // Create a new gateway for connecting to our peer node.        const gateway = new Gateway();        await gateway.connect(ccpPath, { wallet, identity: 'user1', discovery: { enabled: true, asLocalhost: false } });        // Get the network (channel) our contract is deployed to.        const network = await gateway.getNetwork('mychannel');        // Get the contract from the network.        const contract = network.getContract('fabcar');        // Evaluate the specified transaction.        // queryCar transaction - requires 1 argument, ex: ('queryCar', 'CAR4')        // queryAllCars transaction - requires no arguments, ex: ('queryAllCars')        const result = await contract.evaluateTransaction('queryAllCars');        console.log(`Transaction has been evaluated, result is: ${result.toString()}`);        res.status(200).json({response: result.toString()});    } catch (error) {        console.error(`Failed to evaluate transaction: ${error}`);        res.status(500).json({error: error});        process.exit(1);    }});app.get('/api/query/:car_index', async function (req, res) {    try {        // Create a new file system based wallet for managing identities.        const walletPath = path.join(process.cwd(), 'wallet');        const wallet = new FileSystemWallet(walletPath);        console.log(`Wallet path: ${walletPath}`);        // Check to see if we've already enrolled the user.        const userExists = await wallet.exists('user1');        if (!userExists) {            console.log('An identity for the user "user1" does not exist in the wallet');            console.log('Run the registerUser.js application before retrying');            return;        }        // Create a new gateway for connecting to our peer node.        const gateway = new Gateway();        await gateway.connect(ccpPath, { wallet, identity: 'user1', discovery: { enabled: true, asLocalhost: false } });        // Get the network (channel) our contract is deployed to.        const network = await gateway.getNetwork('mychannel');        // Get the contract from the network.        const contract = network.getContract('fabcar');        // Evaluate the specified transaction.        // queryCar transaction - requires 1 argument, ex: ('queryCar', 'CAR4')        // queryAllCars transaction - requires no arguments, ex: ('queryAllCars')        const result = await contract.evaluateTransaction('queryCar', req.params.car_index);        console.log(`Transaction has been evaluated, result is: ${result.toString()}`);        res.status(200).json({response: result.toString()});    } catch (error) {        console.error(`Failed to evaluate transaction: ${error}`);        res.status(500).json({error: error});        process.exit(1);    }});app.post('/api/addcar/', async function (req, res) {    try {        // Create a new file system based wallet for managing identities.        const walletPath = path.join(process.cwd(), 'wallet');        const wallet = new FileSystemWallet(walletPath);        console.log(`Wallet path: ${walletPath}`);        // Check to see if we've already enrolled the user.        const userExists = await wallet.exists('user1');        if (!userExists) {            console.log('An identity for the user "user1" does not exist in the wallet');            console.log('Run the registerUser.js application before retrying');            return;        }        // Create a new gateway for connecting to our peer node.        const gateway = new Gateway();        await gateway.connect(ccpPath, { wallet, identity: 'user1', discovery: { enabled: true, asLocalhost: false } });        // Get the network (channel) our contract is deployed to.        const network = await gateway.getNetwork('mychannel');        // Get the contract from the network.        const contract = network.getContract('fabcar');        // Submit the specified transaction.        // createCar transaction - requires 5 argument, ex: ('createCar', 'CAR12', 'Honda', 'Accord', 'Black', 'Tom')        // changeCarOwner transaction - requires 2 args , ex: ('changeCarOwner', 'CAR10', 'Dave')        await contract.submitTransaction('createCar', req.body.carid, req.body.make, req.body.model, req.body.colour, req.body.owner);        console.log('Transaction has been submitted');        res.send('Transaction has been submitted');        // Disconnect from the gateway.        await gateway.disconnect();    } catch (error) {        console.error(`Failed to submit transaction: ${error}`);        process.exit(1);    }})app.put('/api/changeowner/:car_index', async function (req, res) {    try {        // Create a new file system based wallet for managing identities.        const walletPath = path.join(process.cwd(), 'wallet');        const wallet = new FileSystemWallet(walletPath);        console.log(`Wallet path: ${walletPath}`);        // Check to see if we've already enrolled the user.        const userExists = await wallet.exists('user1');        if (!userExists) {            console.log('An identity for the user "user1" does not exist in the wallet');            console.log('Run the registerUser.js application before retrying');            return;        }        // Create a new gateway for connecting to our peer node.        const gateway = new Gateway();        await gateway.connect(ccpPath, { wallet, identity: 'user1', discovery: { enabled: true, asLocalhost: false } });        // Get the network (channel) our contract is deployed to.        const network = await gateway.getNetwork('mychannel');        // Get the contract from the network.        const contract = network.getContract('fabcar');        // Submit the specified transaction.        // createCar transaction - requires 5 argument, ex: ('createCar', 'CAR12', 'Honda', 'Accord', 'Black', 'Tom')        // changeCarOwner transaction - requires 2 args , ex: ('changeCarOwner', 'CAR10', 'Dave')        await contract.submitTransaction('changeCarOwner', req.params.car_index, req.body.owner);        console.log('Transaction has been submitted');        res.send('Transaction has been submitted');        // Disconnect from the gateway.        await gateway.disconnect();    } catch (error) {        console.error(`Failed to submit transaction: ${error}`);        process.exit(1);    }       })app.listen(8080);

代码中对原来fabcar的query.js和invoke.js修改如下：

• ccpPath修改为当前目录，因为我们要使用同一路径下的连接配置文件connection-org1.json

• 在gateway.connect调用中，修改选项discovery.asLocalhost为false

4、Rest API Server的连接配置文件

API服务依赖于连接配置文件来正确连接fabric网络。文件 connection-org1.json 可以直接从 fabric网络中获取：

{    "name": "first-network-org1",    "version": "1.0.0",    "client": {        "organization": "Org1",        "connection": {            "timeout": {                "peer": {                    "endorser": "300"                }            }        }    },    "organizations": {        "Org1": {            "mspid": "Org1MSP",            "peers": [                "peer0.org1.example.com",                "peer1.org1.example.com"            ],            "certificateAuthorities": [                "ca.org1.example.com"            ]        }    },    "peers": {        "peer0.org1.example.com": {            "url": "grpcs://localhost:7051",            "tlsCACerts": {                "pem": "-----BEGIN CERTIFICATE-----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\nfux9lZWr6gcrIdsn/8fQuWiOIbAgq0HSr60=\n-----END CERTIFICATE-----\n"            },            "grpcOptions": {                "ssl-target-name-override": "peer0.org1.example.com",                "hostnameOverride": "peer0.org1.example.com"            }        },        "peer1.org1.example.com": {            "url": "grpcs://localhost:8051",            "tlsCACerts": {                "pem": "-----BEGIN CERTIFICATE-----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\nfux9lZWr6gcrIdsn/8fQuWiOIbAgq0HSr60=\n-----END CERTIFICATE-----\n"            },            "grpcOptions": {                "ssl-target-name-override": "peer1.org1.example.com",                "hostnameOverride": "peer1.org1.example.com"            }        }    },    "certificateAuthorities": {        "ca.org1.example.com": {            "url": "https://localhost:7054",            "caName": "ca-org1",            "tlsCACerts": {                "pem": "-----BEGIN CERTIFICATE-----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\nTbAFlNCpqr0AQefaRT3ghdURrlbo\n-----END CERTIFICATE-----\n"            },            "httpOptions": {                "verify": false            }        }    }}

当fabcar/startFabric.sh执行时，我们可以交叉检查证书的传播是否正确。 peer0.org1和 peer1.org1 的证书是org1的 TLS root CA 证书签名的。

注意所有的节点都以localhost引用，我们稍后会将其修改为Fabric Node的公开IP地址。

5、用户身份标识

我们已经在Fabric节点上生成了一个用户标识user1并保存在wallet目录中，我们可以看到有三个对应的文件：私钥、公钥和证书对象：

稍后我们会把这些文件拷贝到Rest API Server上。

6、安装Rest API Server节点

1、首先在Rest API Server节点上安装npm、node：

sudo apt-get updatesudo apt install curlcurl -sL https://deb.nodesource.com/setup_8.x | sudo bash -sudo apt install -y nodejssudo apt-get install build-essentialnode -vnpm -v

验证结果如下：

2、然后在Rest API Server上创建一个目录：

mkdir apiservercd apiserver

3、接下来将下面的文件从Fabric节点拷贝到Rest API Server节点。我们 利用loccalhost在两个EC2实例间拷贝：

# localhost (update your own IP of the two servers)# temp is an empty directorycd tempscp -i ~/Downloads/aws.pem ubuntu@[Fabric-Node-IP]:/home/ubuntu/fabric-samples/first-network/connection-org1.json .scp -i ~/Downloads/aws.pem ubuntu@[Fabric-Node-IP]:/home/ubuntu/fabric-samples/fabcar/javascript/package.json .scp -r -i ~/Downloads/aws.pem ubuntu@[Fabric-Node-IP]:/home/ubuntu/fabric-samples/fabcar/javascript/wallet/user1/ .scp -r -i ~/Downloads/aws.pem * ubuntu@[API-Server-Node-IP]:/home/ubuntu/apiserver/

运行结果如下：

4、可以看到现在所有的文件都拷贝到Rest API Server了，为了保持一致，我们将user1/改名为wallet/user1/：

cd apiservermkdir walletmv user1 wallet/user1

运行结果如下：

5、现在在Rest API Server上创建上面的apiserver.js文件。

6、修改连接配置文件connection-org1.json 中的fabric节点的ip地址：

sed -i 's/localhost/[Fabric-Node-IP]/g' connection-org1.json

运行结果如下：

7、在/etc/hosts中增加条目以便可以正确解析fabric节点的IP：

127.0.0.1 localhost[Fabric-Node-IP] orderer.example.com[Fabric-Node-IP] peer0.org1.example.com[Fabric-Node-IP] peer1.org1.example.com[Fabric-Node-IP] peer0.org2.example.com[Fabric-Node-IP] peer1.org2.example.com

运行结果如下：

8、安装必要的依赖包：

npm installnpm install express body-parser --save

9、万事俱备，启动Rest API Server：

node apiserver.js

7、访问API

我们的API服务在8080端口监听，在下面的示例中，我们使用curl来 演示如何访问。

1、查询所有车辆记录

curl http://[API-Server-Node-IP]:8080/api/queryallcars

运行结果如下：

2、添加新的车辆记录并查询

curl -d '{"carid":"CAR12","make":"Honda","model":"Accord","colour":"black","owner":"Tom"}' -H "Content-Type: application/json" -X POST http://[API-Server-Node-IP]:8080/api/addcarcurl http://[API-Server-Node-IP]:8080/api/query/CAR12

运行结果如下：

3、修改车辆所有者并再次查询

curl http://[API-Server-Node-IP]:8080/api/query/CAR4curl -d '{"owner":"KC"}' -H "Content-Type: application/json" -X PUT http://[API-Server-Node-IP]:8080/api/changeowner/CAR4curl http://[API-Server-Node-IP]:8080/api/query/CAR4

运行结果如下：

我们也可以用postman得到同样的结果：

以上是"如何利用Hyperledger Fabric的SDK来开发REST API服务器"这篇文章的所有内容，感谢各位的阅读！相信大家都有了一定的了解，希望分享的内容对大家有所帮助，如果还想学习更多知识，欢迎关注行业资讯频道！