Hyperledger Fabric 提供了軟體開發包/SDK以幫助開發者訪問fabric網路 和部署在網路上的鏈碼，但是Hyperledger Fabric官方沒有提供簡單易用的REST API訪問介面，在這個教程裡我們將學習如何利用Hyperledger Fabric的SDK 來開發REST API伺服器。
1、系統結構概述相關推薦：H..Fabric Java 開發教程 | H..Fabric Nodejs開發教程
整個系統包含兩個物理節點：
Fabric節點：執行Fabric示例中的First Network，並且例項化了Fabcar鏈碼API伺服器節點：執行REST API Server程式碼供外部訪問下面是部署在AWS上的兩個節點例項的情況：
首先參考官方文件安裝hyperledger fabric。
然後執行指令碼fabcar/startFabric.sh：
cd fabric-samples/fabcar./startFabric.sh上述指令碼執行之後，我們就得到一個正常運轉的Hyperledger Fabric網路（著名的演示網路First Network），包含2個機構/4個對等節點， 通道為mychannel，鏈碼Fabcar安裝在全部4個對等節點上並且在mychannel上啟用。賬本中有10條車輛記錄，這是呼叫 合約的initLedger方法的結果。
現在我們為REST API Server準備身份標識資料。使用fabcar/javascript建立一個使用者標識user1，我們將在REST API Server 中使用這個身份標識：
cd javascriptnpm installnode enrollAdmin.jsnode registerUser.jsls wallet/user1執行結果如下：
現在Rest API Server需要的東西都備齊了：
org1的連線配置檔案：first-network/connection-org1.jsonNode.js包檔案：fabcar/package.jsonUser1身份錢包：fabcar/javascript/wallet/user1/後面我們會把這些資料檔案拷貝到Rest API Server。
2、Rest API Server設計我們使用ExressJS來開發API服務，利用query.js和invoke.js 中的程式碼實現與fabric互動的邏輯。API設計如下：
GET /api/queryallcars：返回全部車輛記錄GET /api/query/CarID：返回指定ID的車輛記錄POST /api/addcar/：新增一條新的車輛記錄PUT /api/changeowner/CarID：修改指定ID的車輛記錄3、Rest API Server程式碼實現apiserver.js程式碼如下：
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);程式碼中對原來fabcar的query.js和invoke.js修改如下：
ccpPath修改為當前目錄，因為我們要使用同一路徑下的連線配置檔案connection-org1.json在gateway.connect呼叫中，修改選項discovery.asLocalhost為false4、Rest API Server的連線配置檔案API服務依賴於連線配置檔案來正確連線fabric網路。檔案 connection-org1.json 可以直接從 fabric網路中獲取：
{ "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 } } }}當fabcar/startFabric.sh執行時，我們可以交叉檢查證書的傳播是否正確。 peer0.org1和 peer1.org1 的證書是org1的 TLS root CA 證書籤名的。
注意所有的節點都以localhost引用，我們稍後會將其修改為Fabric Node的 公開IP地址。
5、使用者身份標識我們已經在Fabric節點上生成了一個使用者標識user1並儲存在wallet目錄中， 我們可以看到有三個對應的檔案：私鑰、公鑰和證書物件：
稍後我們會把這些檔案拷貝到Rest API Server上。
6、安裝Rest API Server節點1、首先在Rest API Server節點上安裝npm、node：
驗證結果如下：
2、然後在Rest API Server上建立一個目錄：
mkdir apiservercd apiserver3、接下來將下面的檔案從Fabric節點拷貝到Rest API Server節點。我們 利用loccalhost在兩個EC2例項間拷貝：
# 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/執行結果如下：
4、可以看到現在所有的檔案都拷貝到Rest API Server了，為了保持一致，我們將user1/改名為wallet/user1/：
cd apiservermkdir walletmv user1 wallet/user1執行結果如下：
5、現在在Rest API Server上建立上面的apiserver.js檔案。
6、修改連線配置檔案connection-org1.json 中的fabric節點的ip地址：
sed -i 's/localhost/[Fabric-Node-IP]/g' connection-org1.json執行結果如下：
7、在/etc/hosts中增加條目以便可以正確解析fabric節點的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執行結果如下：
8、安裝必要的依賴包：
npm installnpm install express body-parser --save9、萬事俱備，啟動Rest API Server：
7、訪問APInode apiserver.js我們的API服務在8080埠監聽，在下面的示例中，我們使用curl來 演示如何訪問。
1、查詢所有車輛記錄
curl http://[API-Server-Node-IP]:8080/api/queryallcars執行結果如下：
2、新增新的車輛記錄並查詢
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執行結果如下：
3、修改車輛所有者並再次查詢
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執行結果如下：
我們也可以用postman得到同樣的結果：
匯智網原文連結：http://blog.hubwiz.com/2020/01/06/hyperledger-api-server-impl/
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