这篇文章主要为大家展示了“如何利用Hyperledger Fabric的SDK来开发REST API服务器”，内容简而易懂，条理清晰，希望能够帮助大家解决疑惑，下面让小编带领大家一起研究并学习一下“如何利用Hyperledger Fabric的SDK来开发REST API服务器”这篇文章吧。
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1、系统结构概述
整个系统包含两个物理节点：
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：
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+mh4T7/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+mh4T7/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\naDhLwl3RBO6eKgHh5lHJovIyDJO3jTNb1ix1W86bFjAKBggqhkjOPQQDA
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：
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，欢迎关注创新互联行业资讯频道！
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