为Hyperledger Fabric增加Rest API：设计与实现代码

Hyperledger Fabric 提供了软件开发包/SDK以帮助开发者访问fabric网络和部署在网络上的链码，但是Hyperledger Fabric官方没有提供简单易用的REST API访问接口，在这个教程里我们将学习如何利用Hyperledger Fabric的SDK来开发REST API服务器。

1、系统结构概述

相关推荐：H..Fabric Java 开发教程 |
H..Fabric Nodejs开发教程

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 javascript
npm install
node enrollAdmin.js
node registerUser.js
ls 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 Fabric
const { 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-----\nMIICVjCCAf2gAwIBAgIQEB1sDT11gzTv0/N4cIGoEjAKBggqhkjOPQQDA
jB2MQsw\nCQYDVQQGEwJVUzETMBEGA1UECBMKQ2FsaWZvcm5pYTEWMBQGA1UEBxMNU2FuIEZy\nYW5jaXNjbzEZMBcGA1UEChMQb3JnMS5leGF
tcGxlLmNvbTEfMB0GA1UEAxMWdGxz\nY2Eub3JnMS5leGFtcGxlLmNvbTAeFw0xOTA5MDQwMjQzMDBaFw0yOTA5MDEwMjQz\nMDBaMHYxCzAJB
gNVBAYTAlVTMRMwEQYDVQQIEwpDYWxpZm9ybmlhMRYwFAYDVQQH\nEw1TYW4gRnJhbmNpc2NvMRkwFwYDVQQKExBvcmcxLmV4YW1wbGUuY29tM
R8wHQYD\nVQQDExZ0bHNjYS5vcmcxLmV4YW1wbGUuY29tMFkwEwYHKoZIzj0CAQYIKoZIzj0D\nAQcDQgAEoN0qd5hM2SDfvGzNjTCXuQqyk+X
K4VISa16/y9iXBPpa0onyAXJuv7T0\noPf+mh3T7/g8uYtV2bwTpT2XFO3Q6KNtMGswDgYDVR0PAQH/BAQDAgGmMB0GA1Ud\nJQQWMBQGCCsGA
QUFBwMCBggrBgEFBQcDATAPBgNVHRMBAf8EBTADAQH/MCkGA1Ud\nDgQiBCCalpyChmrLtpgOll6TVmlMOO/2iiyI2PadNPsIYx51mTAKBggqh
kjOPQQD\nAgNHADBEAiBLNoAYWe9LvoxxBxl3sUM64kl7rx6dI3JU+dJG6FRxWgIgCu1ONEyp\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-----\nMIICVjCCAf2gAwIBAgIQEB1sDT11gzTv0/N4cIGoEjAKBggqhkjOPQQDA
jB2MQsw\nCQYDVQQGEwJVUzETMBEGA1UECBMKQ2FsaWZvcm5pYTEWMBQGA1UEBxMNU2FuIEZy\nYW5jaXNjbzEZMBcGA1UEChMQb3JnMS5leGF
tcGxlLmNvbTEfMB0GA1UEAxMWdGxz\nY2Eub3JnMS5leGFtcGxlLmNvbTAeFw0xOTA5MDQwMjQzMDBaFw0yOTA5MDEwMjQz\nMDBaMHYxCzAJB
gNVBAYTAlVTMRMwEQYDVQQIEwpDYWxpZm9ybmlhMRYwFAYDVQQH\nEw1TYW4gRnJhbmNpc2NvMRkwFwYDVQQKExBvcmcxLmV4YW1wbGUuY29tM
R8wHQYD\nVQQDExZ0bHNjYS5vcmcxLmV4YW1wbGUuY29tMFkwEwYHKoZIzj0CAQYIKoZIzj0D\nAQcDQgAEoN0qd5hM2SDfvGzNjTCXuQqyk+X
K4VISa16/y9iXBPpa0onyAXJuv7T0\noPf+mh3T7/g8uYtV2bwTpT2XFO3Q6KNtMGswDgYDVR0PAQH/BAQDAgGmMB0GA1Ud\nJQQWMBQGCCsGA
QUFBwMCBggrBgEFBQcDATAPBgNVHRMBAf8EBTADAQH/MCkGA1Ud\nDgQiBCCalpyChmrLtpgOll6TVmlMOO/2iiyI2PadNPsIYx51mTAKBggqh
kjOPQQD\nAgNHADBEAiBLNoAYWe9LvoxxBxl3sUM64kl7rx6dI3JU+dJG6FRxWgIgCu1ONEyp\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-----\nMIICUTCCAfegAwIBAgIQSiMHm4n9QvhD6wltAHkZPTAKBggqhkjOPQQDA
jBzMQsw\nCQYDVQQGEwJVUzETMBEGA1UECBMKQ2FsaWZvcm5pYTEWMBQGA1UEBxMNU2FuIEZy\nYW5jaXNjbzEZMBcGA1UEChMQb3JnMS5leGF
tcGxlLmNvbTEcMBoGA1UEAxMTY2Eu\nb3JnMS5leGFtcGxlLmNvbTAeFw0xOTA5MDQwMjQzMDBaFw0yOTA5MDEwMjQzMDBa\nMHMxCzAJBgNVB
AYTAlVTMRMwEQYDVQQIEwpDYWxpZm9ybmlhMRYwFAYDVQQHEw1T\nYW4gRnJhbmNpc2NvMRkwFwYDVQQKExBvcmcxLmV4YW1wbGUuY29tMRwwG
gYDVQQD\nExNjYS5vcmcxLmV4YW1wbGUuY29tMFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAE\nz93lOhLJG93uJQgnh93QcPPal5NQXQnAutF
KYkun/eMHMe23wNPd0aJhnXdCjWF8\nMRHVAjtPn4NVCJYiTzSAnaNtMGswDgYDVR0PAQH/BAQDAgGmMB0GA1UdJQQWMBQG\nCCsGAQUFBwMCB
ggrBgEFBQcDATAPBgNVHRMBAf8EBTADAQH/MCkGA1UdDgQiBCDK\naDhLwl3RBO6eKgHh4lHJovIyDJO3jTNb1ix1W86bFjAKBggqhkjOPQQDA
gNIADBF\nAiEA8KTKkjQwb1TduTWWkmsLmKdxrlE6/H7CfsdeGE+onewCIHJ1S0nLhbWYv+G9\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 update
sudo apt install curl
curl -sL https://deb.nodesource.com/setup_8.x | sudo bash -
sudo apt install -y nodejs
sudo apt-get install build-essentialnode -v
npm -v

验证结果如下：

2、然后在Rest API Server上创建一个目录：

mkdir apiserver
cd 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 directory
cd temp
scp -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 apiserver
mkdir wallet
mv 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 install
npm 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/addcar

curl 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/CAR4

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

curl 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：

原文链接：Hyperledger Fabric Rest API服务开发教程 — 汇智网