SpringBoot2 Zookeeper component integration, service coordination in the management structure

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A, Zookeeper basis Introduction

1, the concept Introduction

Zookeeper distributed application is an Apache open source to provide coordinated services for the system architecture. From the perspective of design patterns to look: This is a component based framework for the observer design pattern, is responsible for storing and managing data, the viewer accepts the registration, once the state of the data changes, it will be responsible for notifying Zookeeper already registered in the observation Zookeeper who react accordingly, in order to achieve a similar cluster Master / Slave management. ZooKeeper goal is to better encapsulate complex error-prone critical services, the easy to use interface and efficient performance, function and stability of the system to the user.

2, the basic theory

• data structure

ZooKeeper record similar data structures and Linux file system, as a whole can be seen as a tree, each node called ZNode. Each Znode default 1MB capable of storing data, each ZNode are uniquely identified by its path.

• Node Type

Brief (ephemeral): After the client and the server is disconnected, the node is created automatically deleted.
Persistent (persistent): After the client and the server is disconnected, the node to create a lasting preservation.

• Cluster Service

Zookeeper cluster service is in a cluster by the leader (leader), more followers (follower) of the composition. Leaders responsible for initiating and vote on the resolution, and update the cluster service status. Followers for receiving client requests return the results to the client, to vote in the election Leader process. As long as more than half of the cluster nodes survival, Zookeeper cluster will be able to normal service.

• Data consistency

Each server save a copy of the same data, regardless of the client request to a server process which is a cluster, the data obtained are consistent.

3, application scenarios

• Classic applications: Dubbo service framework registration and discovery;
• Distributed message synchronization and coordination mechanisms;
• Upper and lower dynamic server node;
• Unified configuration management, load balancing, cluster management;

Second, the security management operations

1, the operating authority

ZooKeeper nodes There are five operating authority: CREATE (increase), READ (check), WRITE (change), DELETE (delete), ADMIN (administration) and other related rights, the five set of permissions can be abbreviated as crwda, each word the first character mosaic.

2, authentication:

• world

The default mode, open permissions, meaning the solution for the whole world can freely access.

• auth

The user has authorized and authenticated before they can access.

• digest

Username: Password authentication mode, the actual business development is the most common way.

• IP whitelist

Ip address authorize specified, and the specified point permissions control access.

3, Digest authorization process

• Adding user authentication

addauth digest Username: Password

• Setting permissions

setAcl / path auth: Username: Password: Permissions

• View Acl Set

getAcl /path

• Complete operational processes

-- 添加授权用户
[zk: localhost:2181] addauth digest smile:123456
-- 创建节点
[zk: localhost:2181] create /cicada cicada
-- 节点授权
[zk: localhost:2181] setAcl /cicada auth:smile:123456:cdrwa
-- 查看授权
[zk: localhost:2181] getAcl /cicada

Third, the integration framework SpringBoot2

1, dependent on the core

Curator assembly is open source Apache Zookeeper a client connection and operation, Curator frame Zookeeper native API interface for secondary packaging. ZooKeeper provides a variety of application scenarios: For example: distributed lock service, cluster leadership election, shared counter, caching mechanism, such as a distributed queue API package.

<dependency>
    <groupId>org.apache.curator</groupId>
    <artifactId>curator-framework</artifactId>
    <version>2.12.0</version>
</dependency>
<dependency>
    <groupId>org.apache.curator</groupId>
    <artifactId>curator-recipes</artifactId>
    <version>2.12.0</version>
</dependency>
<dependency>
    <groupId>org.apache.curator</groupId>
    <artifactId>curator-client</artifactId>
    <version>2.12.0</version>
</dependency>

2, Zookeeper parameters

zoo:
  keeper:
    #开启标志
    enabled: true
    #服务器地址
    server: 127.0.0.1:2181
    #命名空间，被称为ZNode
    namespace: cicada
    #权限控制，加密
    digest: smile:123456
    #会话超时时间
    sessionTimeoutMs: 3000
    #连接超时时间
    connectionTimeoutMs: 60000
     #最大重试次数
    maxRetries: 2
    #初始休眠时间
    baseSleepTimeMs: 1000

3, initial configuration service

@Configuration
public class ZookeeperConfig {
    private static final Logger LOGGER = LoggerFactory.getLogger(ZookeeperConfig.class) ;
    @Resource
    private ZookeeperParam zookeeperParam ;
    private static CuratorFramework client = null ;
    /**
     * 初始化
     */
    @PostConstruct
    public void init (){
        //重试策略，初试时间1秒，重试10次
        RetryPolicy policy = new ExponentialBackoffRetry(
                zookeeperParam.getBaseSleepTimeMs(),
                zookeeperParam.getMaxRetries());
        //通过工厂创建Curator
        client = CuratorFrameworkFactory.builder()
                .connectString(zookeeperParam.getServer())
                .authorization("digest",zookeeperParam.getDigest().getBytes())
                .connectionTimeoutMs(zookeeperParam.getConnectionTimeoutMs())
                .sessionTimeoutMs(zookeeperParam.getSessionTimeoutMs())
                .retryPolicy(policy).build();
        //开启连接
        client.start();
        LOGGER.info("zookeeper 初始化完成...");
    }
    public static CuratorFramework getClient (){
        return client ;
    }
    public static void closeClient (){
        if (client != null){
            client.close();
        }
    }
}

4, Series Interface Package

public interface ZookeeperService {
    /**
     * 判断节点是否存在
     */
    boolean isExistNode (final String path) ;
    /**
     * 创建节点
     */
    void createNode (CreateMode mode,String path ) ;
    /**
     * 设置节点数据
     */
    void setNodeData (String path, String nodeData) ;
    /**
     * 创建节点
     */
    void createNodeAndData (CreateMode mode, String path , String nodeData) ;
    /**
     * 获取节点数据
     */
    String getNodeData (String path) ;
    /**
     * 获取节点下数据
     */
    List<String> getNodeChild (String path) ;
    /**
     * 是否递归删除节点
     */
    void deleteNode (String path,Boolean recursive) ;
    /**
     * 获取读写锁
     */
    InterProcessReadWriteLock getReadWriteLock (String path) ;
}

5, interface

@Service
public class ZookeeperServiceImpl implements ZookeeperService {
    private static final Logger LOGGER = LoggerFactory.getLogger(ZookeeperServiceImpl.class);
    @Override
    public boolean isExistNode(String path) {
        CuratorFramework client = ZookeeperConfig.getClient();
        client.sync() ;
        try {
            Stat stat = client.checkExists().forPath(path);
            return client.checkExists().forPath(path) != null;
        } catch (Exception e) {
            LOGGER.error("isExistNode error...", e);
            e.printStackTrace();
        }
        return false;
    }
    @Override
    public void createNode(CreateMode mode, String path) {
        CuratorFramework client = ZookeeperConfig.getClient() ;
        try {
            // 递归创建所需父节点
            client.create().creatingParentsIfNeeded().withMode(mode).forPath(path);
        } catch (Exception e) {
            LOGGER.error("createNode error...", e);
            e.printStackTrace();
        }
    }
    @Override
    public void setNodeData(String path, String nodeData) {
        CuratorFramework client = ZookeeperConfig.getClient() ;
        try {
            // 设置节点数据
            client.setData().forPath(path, nodeData.getBytes("UTF-8"));
        } catch (Exception e) {
            LOGGER.error("setNodeData error...", e);
            e.printStackTrace();
        }
    }
    @Override
    public void createNodeAndData(CreateMode mode, String path, String nodeData) {
        CuratorFramework client = ZookeeperConfig.getClient() ;
        try {
            // 创建节点，关联数据
            client.create().creatingParentsIfNeeded().withMode(mode)
                  .forPath(path,nodeData.getBytes("UTF-8"));
        } catch (Exception e) {
            LOGGER.error("createNode error...", e);
            e.printStackTrace();
        }
    }
    @Override
    public String getNodeData(String path) {
        CuratorFramework client = ZookeeperConfig.getClient() ;
        try {
            // 数据读取和转换
            byte[] dataByte = client.getData().forPath(path) ;
            String data = new String(dataByte,"UTF-8") ;
            if (StringUtils.isNotEmpty(data)){
                return data ;
            }
        }catch (Exception e) {
            LOGGER.error("getNodeData error...", e);
            e.printStackTrace();
        }
        return null;
    }
    @Override
    public List<String> getNodeChild(String path) {
        CuratorFramework client = ZookeeperConfig.getClient() ;
        List<String> nodeChildDataList = new ArrayList<>();
        try {
            // 节点下数据集
            nodeChildDataList = client.getChildren().forPath(path);
        } catch (Exception e) {
            LOGGER.error("getNodeChild error...", e);
            e.printStackTrace();
        }
        return nodeChildDataList;
    }
    @Override
    public void deleteNode(String path, Boolean recursive) {
        CuratorFramework client = ZookeeperConfig.getClient() ;
        try {
            if(recursive) {
                // 递归删除节点
                client.delete().guaranteed().deletingChildrenIfNeeded().forPath(path);
            } else {
                // 删除单个节点
                client.delete().guaranteed().forPath(path);
            }
        } catch (Exception e) {
            LOGGER.error("deleteNode error...", e);
            e.printStackTrace();
        }
    }
    @Override
    public InterProcessReadWriteLock getReadWriteLock(String path) {
        CuratorFramework client = ZookeeperConfig.getClient() ;
        // 写锁互斥、读写互斥
        InterProcessReadWriteLock readWriteLock = new InterProcessReadWriteLock(client, path);
        return readWriteLock ;
    }
}

6, based on Swagger2 Interface

@Api("Zookeeper接口管理")
@RestController
public class ZookeeperApi {
    @Resource
    private ZookeeperService zookeeperService ;
    @ApiOperation(value="查询节点数据")
    @GetMapping("/getNodeData")
    public String getNodeData (String path) {
        return zookeeperService.getNodeData(path) ;
    }
    @ApiOperation(value="判断节点是否存在")
    @GetMapping("/isExistNode")
    public boolean isExistNode (final String path){
        return zookeeperService.isExistNode(path) ;
    }
    @ApiOperation(value="创建节点")
    @GetMapping("/createNode")
    public String createNode (CreateMode mode, String path ){
        zookeeperService.createNode(mode,path) ;
        return "success" ;
    }
    @ApiOperation(value="设置节点数据")
    @GetMapping("/setNodeData")
    public String setNodeData (String path, String nodeData) {
        zookeeperService.setNodeData(path,nodeData) ;
        return "success" ;
    }
    @ApiOperation(value="创建并设置节点数据")
    @GetMapping("/createNodeAndData")
    public String createNodeAndData (CreateMode mode, String path , String nodeData){
        zookeeperService.createNodeAndData(mode,path,nodeData) ;
        return "success" ;
    }
    @ApiOperation(value="递归获取节点数据")
    @GetMapping("/getNodeChild")
    public List<String> getNodeChild (String path) {
        return zookeeperService.getNodeChild(path) ;
    }
    @ApiOperation(value="是否递归删除节点")
    @GetMapping("/deleteNode")
    public String deleteNode (String path,Boolean recursive) {
        zookeeperService.deleteNode(path,recursive) ;
        return "success" ;
    }
}

Fourth, the source address

GitHub·地址
https://github.com/cicadasmile/middle-ware-parent
GitEE·地址
https://gitee.com/cicadasmile/middle-ware-parent