Hyperledger Fabric架构及Java SDK实现

Hyperledger Fabric 整理体系：

Fabric 整体架构和交易流程

Fabric Samples 在Mac部署和运行

Fabric Samples 运行日志记录

Fabric Samples BYFN 命令行详解

Fabric Samples 运行时架构和Java客户端具体实现

运行时架构

各项解释如下：

APP：代表一个客户端或者SDK，作用是创建交易并获取到足够的背书之后向Orderer排序服务节点提交交易请求。（peer和orderer提供了gRPC远程访问接口，供客户端调用）
CA：负责对网络中所有证书进行管理，提供标准的KPI服务
MSP：为客户端和peer提供证书的系统抽象组件
Channel：通道提供了一种通讯机制，将peers和orderer连接在一起，形成一个具有保密性的通讯链路；将一个大网络分割成不同私有子网，进行数据隔离
Orderer：对客户端提交的交易请求进行排序，之后生成区块广播给通道内所有peer节点
Org1：代表联盟中的某-组织
Peer：表示组织中的节点；peer节点以区块的形式从orderer排序服务节点接收有序状态更新，维护状态和账本。fabric中Peer节点可划分如下：
1. Endorsing Peer：根据指定的策略调用智能合约，对结果进行背书，返回提案相应到客户端
2. Committing Peer：验证数据并保存到账本中
3. Anchor Peer：跨组织通讯
4. Leading Peer：做为组织内所有节点的代表连接到Orderer排序服务节点，将从排序服务节点接收到的批量区块广播给组织内的其他节点
Chaincode：链码，部署在fabric的网络节点中，独立运行在具有安全特性的受保护容器中，以gRPC协议与相应Peer节点进行通讯，提供相应的API与账本数据进行交互
Ledger：有排序服务构建的一个全部有序的交易哈希链块，保存在所有的Peer节点中。

Java SDK提供了一种执行用户链码，查询块数据，在通道进行交易及模拟事件的方式。
此模式下，区块链网络由两个组织，每个组织包含两个结点，和一个order服务；将展示怎样创建和初始化通道，安装和部署链码，和执行调用和查询操作。

fabric network

基本原理

在fabric区块链中，应用通过结点RPC协议接口访问链码。

基本流程

类似于Shim API对链码通讯协议的封装，JavaSDK提供了对结点RPC协议接口封装，其入口类为HFClient；对链码的交易和查询操作则封装在channel类中。

基本流程 - 类说明

简单实例

实现User接口
HFClient访问fabric网络身份使用User接口实现。
一个用户的身份由它的证书来标识的，同时交易还需要证书对应的私钥，因此LocalUser的核心逻辑就是利用指定的证书和私钥PEM文件满足User接口的要求。

User类实现
访问链码
创建HFClient实例，然后获取通道对象，就可以查询链码或者提交链码交易。

命令行操作： hyperledger fabric byfn up详解

代码具体实现

运行fabric-samples中fabcar，创建区块链网络
新建Java工程，引入fabric-gateway-java，实现具体实现
pom.xml

    
        
            oss-sonatype
            OSS Sonatype
            https://oss.sonatype.org/content/repositories/snapshots
        
    

    
        
            org.hyperledger.fabric
            fabric-gateway-java
            1.4.1-SNAPSHOT

加入Admins角色：

public class EnrollAdmin {

    static {
        System.setProperty("org.hyperledger.fabric.sdk.service_discovery.as_localhost", "true");
    }

    public static void main(String[] args) throws Exception {

        // Create a CA client for interacting with the CA.
        Properties props = new Properties();
        props.put("pemFile",
            "/Users/macserver/Documents/BlockChain/src/github.com/hyperledger/fabric-samples/first-network/crypto-config/peerOrganizations/org1.example.com/ca/ca.org1.example.com-cert.pem");
        props.put("allowAllHostNames", "true");
        HFCAClient caClient = HFCAClient.createNewInstance("https://localhost:7054", props);
        CryptoSuite cryptoSuite = CryptoSuiteFactory.getDefault().getCryptoSuite();
        caClient.setCryptoSuite(cryptoSuite);

        // Create a wallet for managing identities
        Wallet wallet = Wallet.createFileSystemWallet(Paths.get("wallet"));

        // Check to see if we've already enrolled the admin user.
        boolean adminExists = wallet.exists("admin");
        if (adminExists) {
            System.out.println("An identity for the admin user \"admin\" already exists in the wallet");
            return;
        }

        // Enroll the admin user, and import the new identity into the wallet.
        final EnrollmentRequest enrollmentRequestTLS = new EnrollmentRequest();
        enrollmentRequestTLS.addHost("localhost");
        enrollmentRequestTLS.setProfile("tls");
        Enrollment enrollment = caClient.enroll("admin", "adminpw", enrollmentRequestTLS);
        Identity user = Identity.createIdentity("Org1MSP", enrollment.getCert(), enrollment.getKey());
        wallet.put("admin", user);
        System.out.println("Successfully enrolled user \"admin\" and imported it into the wallet");
    }
}

加入user1角色：

public class RegisterUser {

    static {
        System.setProperty("org.hyperledger.fabric.sdk.service_discovery.as_localhost", "true");
    }

    public static void main(String[] args) throws Exception {

        // Create a CA client for interacting with the CA.
        Properties props = new Properties();
        props.put("pemFile",
            "/Users/macserver/Documents/BlockChain/src/github.com/hyperledger/fabric-samples/first-network/crypto-config/peerOrganizations/org1.example.com/ca/ca.org1.example.com-cert.pem");
        props.put("allowAllHostNames", "true");
        HFCAClient caClient = HFCAClient.createNewInstance("https://localhost:7054", props);
        CryptoSuite cryptoSuite = CryptoSuiteFactory.getDefault().getCryptoSuite();
        caClient.setCryptoSuite(cryptoSuite);

        // Create a wallet for managing identities
        Wallet wallet = Wallet.createFileSystemWallet(Paths.get("wallet"));

        // Check to see if we've already enrolled the user.
        boolean userExists = wallet.exists("user1");
        if (userExists) {
            System.out.println("An identity for the user \"user1\" already exists in the wallet");
            return;
        }

        userExists = wallet.exists("admin");
        if (!userExists) {
            System.out.println("\"admin\" needs to be enrolled and added to the wallet first");
            return;
        }

        Identity adminIdentity = wallet.get("admin");
        User admin = new User() {

            @Override
            public String getName() {
                return "admin";
            }

            @Override
            public Set getRoles() {
                return null;
            }

            @Override
            public String getAccount() {
                return null;
            }

            @Override
            public String getAffiliation() {
                return "org1.department1";
            }

            @Override
            public Enrollment getEnrollment() {
                return new Enrollment() {

                    @Override
                    public PrivateKey getKey() {
                        return adminIdentity.getPrivateKey();
                    }

                    @Override
                    public String getCert() {
                        return adminIdentity.getCertificate();
                    }
                };
            }

            @Override
            public String getMspId() {
                return "Org1MSP";
            }

        };

        // Register the user, enroll the user, and import the new identity into the wallet.
        RegistrationRequest registrationRequest = new RegistrationRequest("user1");
        registrationRequest.setAffiliation("org1.department1");
        registrationRequest.setEnrollmentID("user1");
        String enrollmentSecret = caClient.register(registrationRequest, admin);
        Enrollment enrollment = caClient.enroll("user1", enrollmentSecret);
        Identity user = Identity.createIdentity("Org1MSP", enrollment.getCert(), enrollment.getKey());
        wallet.put("user1", user);
        System.out.println("Successfully enrolled user \"user1\" and imported it into the wallet");
    }

}

客户端：查询及添加新数据

public class ClientApp {

    static {
        System.setProperty("org.hyperledger.fabric.sdk.service_discovery.as_localhost", "true");
    }

    public static void main(String[] args) throws Exception {
        // Load a file system based wallet for managing identities.
        Path walletPath = Paths.get("wallet");
        Wallet wallet = Wallet.createFileSystemWallet(walletPath);

        // load a CCP
        Path networkConfigPath = Paths.get("/Users/macserver/Documents/BlockChain/src/github.com/hyperledger/fabric-samples/fabcar", "..", "first-network", "connection-org1.yaml");

        Gateway.Builder builder = Gateway.createBuilder();
        builder.identity(wallet, "user1").networkConfig(networkConfigPath).discovery(true);

        // create a gateway connection
        try (Gateway gateway = builder.connect()) {

            // get the network and contract
            Network network = gateway.getNetwork("mychannel");
            Contract contract = network.getContract("fabcar");

            byte[] result;

            result = contract.evaluateTransaction("queryAllCars");
            System.out.println(new String(result));

            contract.submitTransaction("createCar", "CAR10", "VW", "Polo", "Grey", "Mary");

            result = contract.evaluateTransaction("queryCar", "CAR10");
            System.out.println(new String(result));

            contract.submitTransaction("changeCarOwner", "CAR10", "Archie");

            result = contract.evaluateTransaction("queryCar", "CAR10");
            System.out.println(new String(result));
        }
    }

}

实现方式二

如果跳过gateway，直接使用fabric-sdk-java，数据查询-实现代码如下：

private static void queryAllCars() throws Exception {
        HFClient hfClient = HFClient.createNewInstance();

        CryptoSuite cryptoSuite = CryptoSuiteFactory.getDefault().getCryptoSuite();
        hfClient.setCryptoSuite(cryptoSuite);

        Enrollment enrollment = new X509Enrollment(getPrivateKey(Paths.get("wallet/user1/user1-priv")), getCertificate(certificate_user1));
        User user = new User() {
            @Override
            public String getName() {
                return "gateway";
            }

            @Override
            public Set getRoles() {
                return Collections.emptySet();
            }

            @Override
            public String getAccount() {
                return "";
            }

            @Override
            public String getAffiliation() {
                return "";
            }

            @Override
            public Enrollment getEnrollment() {
                return enrollment;
            }

            @Override
            public String getMspId() {
                return "Org1MSP";
            }
        };

        hfClient.setUserContext(user);

        NetworkConfig networkConfig = NetworkConfig.fromYamlFile(new File(path + "first-network/connection-org1.yaml"));

        Channel channel = hfClient.newChannel("mychannel");

        List peerNames = networkConfig.getClientOrganization().getPeerNames();
        for (String name : peerNames) {
            String url = networkConfig.getPeerUrl(name);
            Properties props = networkConfig.getPeerProperties(name);
            System.err.println("xxxxxxxxx：" + name + "..." + url);
            Peer peer = hfClient.newPeer(name, url, props);

            Channel.PeerOptions peerOptions = Channel.PeerOptions.createPeerOptions().setPeerRoles(EnumSet.allOf(Peer.PeerRole.class));
            channel.addPeer(peer, peerOptions);
        }

        channel.initialize();


        QueryByChaincodeRequest request = QueryByChaincodeRequest.newInstance(user);

        request.setChaincodeID(getChaincodeId("fabcar"));
        request.setFcn("queryAllCars");
        request.setArgs("");

        Collection responses = channel.queryByChaincode(request, Collections.singletonList(channel.getPeers().iterator().next()));
        ProposalResponse response = responses.iterator().next();
        byte[] bytes = response.getChaincodeActionResponsePayload();

        System.err.println("xxxxxxx：" + new String(bytes));
    }

    private static String getCertificate(String certificate) {
        BufferedReader certReader = new BufferedReader(new StringReader(certificate));
        return certReader.lines().collect(Collectors.joining("\n", "", "\n"));
    }

    private static PrivateKey getPrivateKey(Path pemFile) {
        try {
            PEMParser parser = new PEMParser(Files.newBufferedReader(pemFile));
            Object key = parser.readObject();
            JcaPEMKeyConverter converter = new JcaPEMKeyConverter();
            return converter.getPrivateKey((PrivateKeyInfo) key);
        } catch (IOException e) {
            System.err.println("private key 获取失败");
            return null;
        }
    }

    private static ChaincodeID getChaincodeId(String chaincodeId) {
        return ChaincodeID.newBuilder()
                .setName(chaincodeId)
                .build();
    }