（九）分布式服务----Zookeeper注册中心

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首先看一下几种注册中心：

最老的就是Zookeeper了， 比较新的有Eureka，Consul 都可以做注册中心。可以自行搜索对比三者的优缺点。

Zookeeper 最开始就是hadoop大家族中的一员，用于做协调的框架，后来已经是apache的子项目了。

几年前大数据很火的时候，只要学hadoop必学zookeeper，当然还有其他成员。

大数据简单说就是分布式，比如分布式文件存储hdfs，分布式数据库hbase，分布式协调zookeeper，还有kafka，Flume等等都是hadoop大家族。

zookeeper，现在更多被用来做注册中心，比如阿里的开源SOA框架dubbo就经常搭配zookeeper做注册中心。

Eureka：java的微服务框架Spring Cloud中内部已经集成了Eureka注册中心。

我选择zookeeper，不是因为他比另外两个强，而是因为我几年前就已经学习过一些zookeeper的原理，上手更容易。网络上学习书籍、资料、视频教程也特别多，学习资料完善。

注册中心的基本功能：

1. 注册服务，有点类似DNS，所有的服务注册到注册中心，包含服务的地址等信息。

2. 服务订阅，客户端请求服务，注册中心就要把那些能用的服务器地址告诉客户端，服务端有变动时，注册中心也能及时通知到客户端。

3. 性能好且高可用，注册中心自身也是一个集群，如果只有一个注册中心机器的话那岂不是把注册中心累死啊，而且他一旦坏了以后，那客户端都找不到服务器了。所有注册中心就有很多台，其中只有一个老大（leader），老大用来写，小弟用来读。就是说老大来决定一台服务器能不能注册进来，小弟负责帮助客户端查找服务器。因为注册服务的次数是很少的，通常有新服务器加入才需要注册，但是客户端订阅那就很多了，所以注册中心只有一个leader。leader万一坏掉的话，会从小弟中选举出一个来当老大接替工作。

上面提到说zookeeper集群，就是说有很多台机器做zookeeper机器，但是这些机器里存储的东西基本上都是一样的，就是说客户端不管连到哪个zookeeper 都是一样的，能做服务订阅。

每一个zookeeper 中都有很多节点（Znode）。

接下来说的zookeeper节点和集群完全不是一回事。 有些人喜欢吧集群中的每一台zookeeper机器称为一个节点，但是这个节点（zookeeper机器）和我说的节点（Znode）完全不是一回事。

如下图：

 本例的图中可以看到，一共有5台机器，每台机器都有5个znode，Znode下面的子节点就更多了。

先看5台机器：

一台leader，老大，上文已经介绍，服务都从这些注册写入。

两台follower，小弟，平时用于服务订阅，老大挂掉以后，follower内部就会自行选出老大。

两台observer，观察者，就是属于无业游民，只能看，没有选老大的资格，不能参与竞选也不能投票，唯一的功能就是服务订阅。

　　observer模式需要手动开启，为什么会出现observer呢，是因为机器太多的话，每个机器都有选举权的话特别影响性能。全中国14亿人口，每个人都参与国家竞选的话，效率极低。所以呢，选举的工作就交给follower完成就行了，只需要确保一直都有leader接班人就好。

再看看zookeeper有什么基本功能：

基本功能很简单，组合以后却可以完成各种复杂工作。

1. 可以创建：临时节点（断开连接时便删除节点） 和 持久化节点（必须手动删除节点）。

2. 可以创建：无序节点 和 有序节点。

3. 节点上可以添加watcher监听功能，监听该节点的增删改，然后触发自定义的事件。

看看这些功能怎么用：

1. 节点： 每次注册一个服务就创建一个节点，节点的名称（Key）就是服务的名称，服务的详细信息存储在节点value中，客户端通过key找到对应的节点，再找打节点中的value。

2. 临时节点：服务端注册一个服务时创建一个临时节点，服务断开时，临时节点自动销毁，自动完成服务注销。

3. watcher监听： 客户端在注册中心订阅了一个服务的时候，同时在这个服务所在的节点上加一个监听事件，每当服务节点信息有变化的时候，注册中心会自动回调通知客户端。

4. 有序临时节点：分布式锁或者分布式队列（这里与服务注册无关），客户端1想要操作一条数据的时候，在A节点下创建一个有序临时节点，自动分配编号001；客户端1也要操作该数据的时候，在A节点下也创建一个有序临时节点，自动分配编号002。只有编号最小的子节点才会被执行，因此001节点会被执行，客户端1执行完毕后，自动删除001节点，此时002编号为最小子节点。即锁的概念，不能同时操作同一数据；也可以做队列，按照先后顺序依次执行。

5. 有序临时节点+watcher监听： 上面第4条中说到每次执行编号最小的节点，因此需要有一个程序，每次都需要遍历全部节点，然后找出最小的节点，假如是002节点，这时客户端2开始执行。但是添加监听机制以后就不一样了，002监听001,003监听比他小一号的002，这样001销毁的同时通知002开始执行，002销毁的时候通知003开始执行，不需要遍历最小节点，也能有序依次执行。

6. 临时节点+watcher监听： 集群master选举以及高可用。比如hadoop集群，也有一个resourcemanager资源管理器，负责调度其它节点机器，相当于hadoop集群的leader节点。这个leader就可以交由zookeeper管理，所有的hadoop机器同时在zookeeper中创建一个同名的临时节点，由于是同名互斥的节点，因此只有一个节点能被创建，成功创建这个节点的hadoop机器就是leader。同时添加Watcher监听，这个leader只要断开连接，临时节点自动销毁，触发监听，其它hadoop开始新一轮的master选举。这也是zookeeper最初在hadoop家族中的重要使命。

7....... 还要很多地方都能用zookeeper，简直无所不能，而且自身也是高可用，高性能，牛x

zookeeper本身的操作还是很简单的，无非就是节点的增删改查，可以选择要创建节点的类型，还有就是在节点上添加watcher监听器。就这些。

文件结构：

上代码：

zookeeper客户端管理类：

public class ZookeeperClientProvider
    {
        private ConfigInfo _config;
        private readonly ILogger<ZookeeperClientProvider> _logger;
        private readonly Dictionary<string, ZooKeeper> _zookeeperClients = new Dictionary<string, ZooKeeper>();

        public ZookeeperClientProvider(ConfigInfo config, ILogger<ZookeeperClientProvider> logger)
        {
            _config = config;
            _logger = logger;
        }

        public async Task<ZooKeeper> GetZooKeeper()
        {
            return await CreateZooKeeper(_config.Addresses.FirstOrDefault());
        }
        public async Task<ZooKeeper> CreateZooKeeper(string address)
        {
            if (!_zookeeperClients.TryGetValue(address, out ZooKeeper result))
            {
                await Task.Run(() =>
                {
                    result = new ZooKeeper(address, (int)_config.SessionTimeout.TotalMilliseconds,
                        new ReconnectionWatcher(
                            async () =>
                            {
                                if (_zookeeperClients.Remove(address, out ZooKeeper value))
                                {
                                    await value.closeAsync();
                                }
                                await CreateZooKeeper(address);
                            }));
                    _zookeeperClients.TryAdd(address, result);
                });
            }
            return result;
        }

        public async Task<IEnumerable<ZooKeeper>> GetZooKeepers()
        {
            var result = new List<ZooKeeper>();
            foreach (var address in _config.Addresses)
            {
                result.Add(await CreateZooKeeper(address));
            }
            return result;
        }
    }

zookeeper服务注册类：

/// <summary>
    /// 一个抽象的服务路由发现者。
    /// </summary>
    public interface IServiceRouteManager
    {

        /// <summary>
        /// 服务路由被创建。
        /// </summary>
        event EventHandler<ServiceRouteEventArgs> Created;

        /// <summary>
        /// 服务路由被删除。
        /// </summary>
        event EventHandler<ServiceRouteEventArgs> Removed;

        /// <summary>
        /// 服务路由被修改。
        /// </summary>
        event EventHandler<ServiceRouteChangedEventArgs> Changed;

        /// <summary>
        /// 获取所有可用的服务路由信息。
        /// </summary>
        /// <returns>服务路由集合。</returns>
        Task<IEnumerable<ServiceRoute>> GetRoutesAsync();

        /// <summary>
        /// 设置服务路由。
        /// </summary>
        /// <param name="routes">服务路由集合。</param>
        /// <returns>一个任务。</returns>
        Task SetRoutesAsync(IEnumerable<ServiceRoute> routes);

        /// <summary>
        /// 移除地址列表
        /// </summary>
        /// <param name="routes">地址列表。</param>
        /// <returns>一个任务。</returns>
        Task RemveAddressAsync(IEnumerable<string> Address);
        /// <summary>
        /// 清空所有的服务路由。
        /// </summary>
        /// <returns>一个任务。</returns>
        Task ClearAsync();
    }

    /// <summary>
    /// 服务路由事件参数。
    /// </summary>
    public class ServiceRouteEventArgs
    {
        public ServiceRouteEventArgs(ServiceRoute route)
        {
            Route = route;
        }

        /// <summary>
        /// 服务路由信息。
        /// </summary>
        public ServiceRoute Route { get; private set; }
    }

    /// <summary>
    /// 服务路由变更事件参数。
    /// </summary>
    public class ServiceRouteChangedEventArgs : ServiceRouteEventArgs
    {
        public ServiceRouteChangedEventArgs(ServiceRoute route, ServiceRoute oldRoute) : base(route)
        {
            OldRoute = oldRoute;
        }

        /// <summary>
        /// 旧的服务路由信息。
        /// </summary>
        public ServiceRoute OldRoute { get; set; }
    }

public class ZooKeeperServiceRouteManager : IServiceRouteManager, IDisposable
    {
        private readonly ConfigInfo _configInfo;
        private readonly ISerializer<byte[]> _serializer;
        private readonly ILogger<ZooKeeperServiceRouteManager> _logger;
        private ServiceRoute[] _routes;
        private readonly ZookeeperClientProvider _zookeeperClientProvider;

        public ZooKeeperServiceRouteManager(ConfigInfo configInfo, ISerializer<byte[]> serializer,
            ISerializer<string> stringSerializer,
            ILogger<ZooKeeperServiceRouteManager> logger,
            ZookeeperClientProvider zookeeperClientProvider)
        {
            _configInfo = configInfo;
            _serializer = serializer;
            _logger = logger;
            _zookeeperClientProvider = zookeeperClientProvider;
            EnterRoutes().Wait();
        }

        private EventHandler<ServiceRouteEventArgs> _created;
        private EventHandler<ServiceRouteEventArgs> _removed;
        private EventHandler<ServiceRouteChangedEventArgs> _changed;

        /// <summary>
        /// 服务路由被创建。
        /// </summary>
        public event EventHandler<ServiceRouteEventArgs> Created
        {
            add { _created += value; }
            remove { _created -= value; }
        }

        /// <summary>
        /// 服务路由被删除。
        /// </summary>
        public event EventHandler<ServiceRouteEventArgs> Removed
        {
            add { _removed += value; }
            remove { _removed -= value; }
        }

        /// <summary>
        /// 服务路由被修改。
        /// </summary>
        public event EventHandler<ServiceRouteChangedEventArgs> Changed
        {
            add { _changed += value; }
            remove { _changed -= value; }
        }



        protected void OnCreated(params ServiceRouteEventArgs[] args)
        {
            if (_created == null)
                return;

            foreach (var arg in args)
                _created(this, arg);
        }

        protected void OnChanged(params ServiceRouteChangedEventArgs[] args)
        {
            if (_changed == null)
                return;

            foreach (var arg in args)
                _changed(this, arg);
        }

        protected void OnRemoved(params ServiceRouteEventArgs[] args)
        {
            if (_removed == null)
                return;

            foreach (var arg in args)
                _removed(this, arg);
        }


        /// <summary>
        /// 获取所有可用的服务路由信息。
        /// </summary>
        /// <returns>服务路由集合。</returns>
        public async Task<IEnumerable<ServiceRoute>> GetRoutesAsync()
        {
            await EnterRoutes();
            return _routes;
        }

        /// <summary>
        /// 清空所有的服务路由。
        /// </summary>
        /// <returns>一个任务。</returns>
        public async Task ClearAsync()
        {
            if (_logger.IsEnabled(LogLevel.Information))
                _logger.LogInformation("准备清空所有路由配置。");
            var zooKeepers = await _zookeeperClientProvider.GetZooKeepers();
            foreach (var zooKeeper in zooKeepers)
            {
                var path = _configInfo.RoutePath;
                var childrens = path.Split(new[] { '/' }, StringSplitOptions.RemoveEmptyEntries);

                var index = 0;
                while (childrens.Count() > 1)
                {
                    var nodePath = "/" + string.Join("/", childrens);

                    if (await zooKeeper.existsAsync(nodePath) != null)
                    {
                        var result = await zooKeeper.getChildrenAsync(nodePath);
                        if (result?.Children != null)
                        {
                            foreach (var child in result.Children)
                            {
                                var childPath = $"{nodePath}/{child}";
                                if (_logger.IsEnabled(LogLevel.Debug))
                                    _logger.LogDebug($"准备删除：{childPath}。");
                                await zooKeeper.deleteAsync(childPath);
                            }
                        }
                        if (_logger.IsEnabled(LogLevel.Debug))
                            _logger.LogDebug($"准备删除：{nodePath}。");
                        await zooKeeper.deleteAsync(nodePath);
                    }
                    index++;
                    childrens = childrens.Take(childrens.Length - index).ToArray();
                }
                if (_logger.IsEnabled(LogLevel.Information))
                    _logger.LogInformation("路由配置清空完成。");
            }
        }

        /// <summary>
        /// 设置服务路由。
        /// </summary>
        /// <param name="routes">服务路由集合。</param>
        /// <returns>一个任务。</returns>
        public async Task SetRoutesAsync(IEnumerable<ServiceRoute> routes)
        {
            var hostAddr = NetUtils.GetHostAddress();
            var serviceRoutes = await GetRoutes(routes.Select(p => p.serviceRouteDescriptor.Id));
            if (serviceRoutes.Count() > 0)
            {
                foreach (var route in routes)
                {
                    var serviceRoute = serviceRoutes.Where(p => p.serviceRouteDescriptor.Id == route.serviceRouteDescriptor.Id).FirstOrDefault();
                    if (serviceRoute != null)
                    {
                        var addresses = serviceRoute.Address.Concat(
                          route.Address.Except(serviceRoute.Address)).ToList();

                        foreach (var address in route.Address)
                        {
                            addresses.Remove(addresses.Where(p => p.ToString() == address.ToString()).FirstOrDefault());
                            addresses.Add(address);
                        }
                        route.Address = addresses;
                    }
                }
            }
            await RemoveExceptRoutesAsync(routes, hostAddr);

            if (_logger.IsEnabled(LogLevel.Information))
                _logger.LogInformation("准备添加服务路由。");
            var zooKeepers = await _zookeeperClientProvider.GetZooKeepers();
            foreach (var zooKeeper in zooKeepers)
            {
                await CreateSubdirectory(zooKeeper, _configInfo.RoutePath);

                var path = _configInfo.RoutePath;
                if (!path.EndsWith("/"))
                    path += "/";

                routes = routes.ToArray();

                foreach (var serviceRoute in routes)
                {
                    var nodePath = $"{path}{serviceRoute.serviceRouteDescriptor.Id}";
                    var nodeData = _serializer.Serialize(serviceRoute);
                    if (await zooKeeper.existsAsync(nodePath) == null)
                    {
                        if (_logger.IsEnabled(LogLevel.Debug))
                            _logger.LogDebug($"节点：{nodePath}不存在将进行创建。");

                        await zooKeeper.createAsync(nodePath, nodeData, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
                    }
                    else
                    {
                        if (_logger.IsEnabled(LogLevel.Debug))
                            _logger.LogDebug($"将更新节点：{nodePath}的数据。");

                        var onlineData = (await zooKeeper.getDataAsync(nodePath)).Data;
                        if (!DataEquals(nodeData, onlineData))
                            await zooKeeper.setDataAsync(nodePath, nodeData);
                    }
                }
                if (_logger.IsEnabled(LogLevel.Information))
                    _logger.LogInformation("服务路由添加成功。");
            }
        }

        public async Task RemveAddressAsync(IEnumerable<string> Address)
        {
            var routes = await GetRoutesAsync();
            foreach (var route in routes)
            {
                route.Address = route.Address.Except(Address);
            }
            await SetRoutesAsync(routes);
        }

        private async Task RemoveExceptRoutesAsync(IEnumerable<ServiceRoute> routes, string hostAddr)
        {
            var path = _configInfo.RoutePath;
            if (!path.EndsWith("/"))
                path += "/";
            routes = routes.ToArray();
            var zooKeepers = await _zookeeperClientProvider.GetZooKeepers();
            foreach (var zooKeeper in zooKeepers)
            {
                if (_routes != null)
                {
                    var oldRouteIds = _routes.Select(i => i.serviceRouteDescriptor.Id).ToArray();
                    var newRouteIds = routes.Select(i => i.serviceRouteDescriptor.Id).ToArray();
                    var deletedRouteIds = oldRouteIds.Except(newRouteIds).ToArray();
                    foreach (var deletedRouteId in deletedRouteIds)
                    {
                        var addresses = _routes.Where(p => p.serviceRouteDescriptor.Id == deletedRouteId).Select(p => p.Address).FirstOrDefault();
                        if (addresses.Contains(hostAddr))
                        {
                            var nodePath = $"{path}{deletedRouteId}";
                            await zooKeeper.deleteAsync(nodePath);
                        }
                    }
                }
            }
        }

        private async Task CreateSubdirectory(ZooKeeper zooKeeper, string path)
        {
            if (await zooKeeper.existsAsync(path) != null)
                return;

            if (_logger.IsEnabled(LogLevel.Information))
                _logger.LogInformation($"节点{path}不存在，将进行创建。");

            var childrens = path.Split(new[] { '/' }, StringSplitOptions.RemoveEmptyEntries);
            var nodePath = "/";

            foreach (var children in childrens)
            {
                nodePath += children;
                if (await zooKeeper.existsAsync(nodePath) == null)
                {
                    await zooKeeper.createAsync(nodePath, null, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
                }
                nodePath += "/";
            }
        }

        private async Task<ServiceRoute> GetRoute(byte[] data)
        {
            if (_logger.IsEnabled(LogLevel.Debug))
                _logger.LogDebug($"准备转换服务路由，配置内容：{Encoding.UTF8.GetString(data)}。");

            if (data == null)
                return null;

            return await Task.Run(() =>
            {
                return _serializer.Deserialize<ServiceRoute>(data);
            });
        }

        private async Task<ServiceRoute> GetRoute(string path)
        {
            ServiceRoute result = null;
            var zooKeeper = await GetZooKeeper();
            var watcher = new NodeMonitorWatcher(GetZooKeeper(), path,
                 async (oldData, newData) => await NodeChange(oldData, newData));
            if (await zooKeeper.existsAsync(path) != null)
            {
                var data = (await zooKeeper.getDataAsync(path, watcher)).Data;
                watcher.SetCurrentData(data);
                result = await GetRoute(data);
            }
            return result;
        }

        private async Task<ServiceRoute[]> GetRoutes(IEnumerable<string> childrens)
        {
            var rootPath = _configInfo.RoutePath;
            if (!rootPath.EndsWith("/"))
                rootPath += "/";

            childrens = childrens.ToArray();
            var routes = new List<ServiceRoute>(childrens.Count());

            foreach (var children in childrens)
            {
                if (_logger.IsEnabled(LogLevel.Debug))
                    _logger.LogDebug($"准备从节点：{children}中获取路由信息。");

                var nodePath = $"{rootPath}{children}";
                var route = await GetRoute(nodePath);
                if (route != null)
                    routes.Add(route);
            }

            return routes.ToArray();
        }

        private async Task EnterRoutes()
        {
            if (_routes != null)
                return;
            var zooKeeper = await GetZooKeeper();
            var watcher = new ChildrenMonitorWatcher(GetZooKeeper(), _configInfo.RoutePath,
             async (oldChildrens, newChildrens) => await ChildrenChange(oldChildrens, newChildrens));
            if (await zooKeeper.existsAsync(_configInfo.RoutePath, watcher) != null)
            {
                var result = await zooKeeper.getChildrenAsync(_configInfo.RoutePath, watcher);
                var childrens = result.Children.ToArray();
                watcher.SetCurrentData(childrens);
                _routes = await GetRoutes(childrens);
            }
            else
            {
                if (_logger.IsEnabled(LogLevel.Warning))
                    _logger.LogWarning($"无法获取路由信息，因为节点：{_configInfo.RoutePath}，不存在。");
                _routes = new ServiceRoute[0];
            }
        }

        private static bool DataEquals(IReadOnlyList<byte> data1, IReadOnlyList<byte> data2)
        {
            if (data1.Count != data2.Count)
                return false;
            for (var i = 0; i < data1.Count; i++)
            {
                var b1 = data1[i];
                var b2 = data2[i];
                if (b1 != b2)
                    return false;
            }
            return true;
        }

        public async Task NodeChange(byte[] oldData, byte[] newData)
        {
            if (DataEquals(oldData, newData))
                return;

            var newRoute = await GetRoute(newData);
            //得到旧的路由。
            var oldRoute = _routes.FirstOrDefault(i => i.serviceRouteDescriptor.Id == newRoute.serviceRouteDescriptor.Id);

            lock (_routes)
            {
                //删除旧路由，并添加上新的路由。
                _routes =
                    _routes
                        .Where(i => i.serviceRouteDescriptor.Id != newRoute.serviceRouteDescriptor.Id)
                        .Concat(new[] { newRoute }).ToArray();
            }

            //触发路由变更事件。
            OnChanged(new ServiceRouteChangedEventArgs(newRoute, oldRoute));
        }

        public async Task ChildrenChange(string[] oldChildrens, string[] newChildrens)
        {
            if (_logger.IsEnabled(LogLevel.Debug))
                _logger.LogDebug($"最新的节点信息：{string.Join(",", newChildrens)}");

            if (_logger.IsEnabled(LogLevel.Debug))
                _logger.LogDebug($"旧的节点信息：{string.Join(",", oldChildrens)}");

            //计算出已被删除的节点。
            var deletedChildrens = oldChildrens.Except(newChildrens).ToArray();
            //计算出新增的节点。
            var createdChildrens = newChildrens.Except(oldChildrens).ToArray();

            if (_logger.IsEnabled(LogLevel.Debug))
                _logger.LogDebug($"需要被删除的路由节点：{string.Join(",", deletedChildrens)}");
            if (_logger.IsEnabled(LogLevel.Debug))
                _logger.LogDebug($"需要被添加的路由节点：{string.Join(",", createdChildrens)}");

            //获取新增的路由信息。
            var newRoutes = (await GetRoutes(createdChildrens)).ToArray();

            var routes = _routes.ToArray();
            lock (_routes)
            {
                _routes = _routes
                    //删除无效的节点路由。
                    .Where(i => !deletedChildrens.Contains(i.serviceRouteDescriptor.Id))
                    //连接上新的路由。
                    .Concat(newRoutes)
                    .ToArray();
            }
            //需要删除的路由集合。
            var deletedRoutes = routes.Where(i => deletedChildrens.Contains(i.serviceRouteDescriptor.Id)).ToArray();
            //触发删除事件。
            OnRemoved(deletedRoutes.Select(route => new ServiceRouteEventArgs(route)).ToArray());

            //触发路由被创建事件。
            OnCreated(newRoutes.Select(route => new ServiceRouteEventArgs(route)).ToArray());

            if (_logger.IsEnabled(LogLevel.Information))
                _logger.LogInformation("路由数据更新成功。");
        }


        /// <summary>Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.</summary>
        public void Dispose()
        {
        }

        private async Task<ZooKeeper> GetZooKeeper()
        {
            return await _zookeeperClientProvider.GetZooKeeper();
        }

    }

zookeeper连接配置类：

public class ConfigInfo
    {
        /// <summary>
        /// 初始化会话超时为20秒的Zookeeper配置信息。
        /// </summary>
        /// <param name="connectionString">连接字符串。</param>
        /// <param name="routePath">路由配置路径。</param>
        /// <param name="subscriberPath">订阅者配置路径</param>
        /// <param name="commandPath">服务命令配置路径</param>
        /// <param name="cachePath">缓存中心配置路径</param>
        /// <param name="mqttRoutePath">mqtt路由配置路径</param>
        /// <param name="chRoot">根节点。</param>
        public ConfigInfo(string connectionString, string routePath = "/services/serviceRoutes",
            string subscriberPath = "/services/serviceSubscribers",
            string commandPath = "/services/serviceCommands",
            string cachePath = "/services/serviceCaches",
            string mqttRoutePath = "/services/mqttServiceRoutes",
            string chRoot = null,
            bool reloadOnChange = false, bool enableChildrenMonitor = false) : this(connectionString,
                TimeSpan.FromSeconds(20),
                routePath,
                subscriberPath,
                commandPath,
                cachePath,
                mqttRoutePath,
                chRoot,
                reloadOnChange, enableChildrenMonitor)
        {
        }

        /// <summary>
        /// 初始化Zookeeper配置信息。
        /// </summary>
        /// <param name="connectionString">连接字符串。</param>
        /// <param name="routePath">路由配置路径。</param>
        /// <param name="commandPath">服务命令配置路径</param>
        /// <param name="subscriberPath">订阅者配置路径</param>
        /// <param name="sessionTimeout">会话超时时间。</param>
        /// <param name="cachePath">缓存中心配置路径</param>
        /// <param name="mqttRoutePath">mqtt路由配置路径</param>
        /// <param name="chRoot">根节点。</param>
        public ConfigInfo(string connectionString, TimeSpan sessionTimeout, string routePath = "/services/serviceRoutes",
            string subscriberPath = "/services/serviceSubscribers",
            string commandPath = "/services/serviceCommands",
            string cachePath = "/services/serviceCaches",
            string mqttRoutePath = "/services/mqttServiceRoutes",
            string chRoot = null,
            bool reloadOnChange = false, bool enableChildrenMonitor = false)
        {
            CachePath = cachePath;
            ReloadOnChange = reloadOnChange;
            ChRoot = chRoot;
            CommandPath = commandPath;
            SubscriberPath = subscriberPath;
            ConnectionString = connectionString;
            RoutePath = routePath;
            SessionTimeout = sessionTimeout;
            MqttRoutePath = mqttRoutePath;
            EnableChildrenMonitor = enableChildrenMonitor;
            Addresses = connectionString?.Split(",");
        }

        public bool EnableChildrenMonitor { get; set; }

        public bool ReloadOnChange { get; set; }

        /// <summary>
        /// 连接字符串。
        /// </summary>
        public string ConnectionString { get; set; }

        /// <summary>
        /// 命令配置路径
        /// </summary>
        public string CommandPath { get; set; }

        /// <summary>
        /// 路由配置路径。
        /// </summary>
        public string RoutePath { get; set; }

        /// <summary>
        /// 订阅者配置路径
        /// </summary>
        public string SubscriberPath { get; set; }

        /// <summary>
        /// 会话超时时间。
        /// </summary>
        public TimeSpan SessionTimeout { get; set; }

        /// <summary>
        /// 根节点。
        /// </summary>
        public string ChRoot { get; set; }


        public IEnumerable<string> Addresses { get; set; }

        /// <summary>
        /// 缓存中心配置中心
        /// </summary>
        public string CachePath { get; set; }


        /// <summary>
        /// Mqtt路由配置路径。
        /// </summary>
        public string MqttRoutePath { get; set; }
    }

路由和路由描述：

public class ServiceRoute
    {
        /// <summary>
        /// 服务可用地址。
        /// </summary>
        public IEnumerable<string> Address { get; set; }
        /// <summary>
        /// 服务描述符。
        /// </summary>
        public ServiceRouteDescriptor serviceRouteDescriptor { get; set; }

        #region Equality members

        /// <summary>Determines whether the specified object is equal to the current object.</summary>
        /// <returns>true if the specified object  is equal to the current object; otherwise, false.</returns>
        /// <param name="obj">The object to compare with the current object. </param>
        public override bool Equals(object obj)
        {
            var model = obj as ServiceRoute;
            if (model == null)
                return false;

            if (obj.GetType() != GetType())
                return false;

            if (model.serviceRouteDescriptor != serviceRouteDescriptor)
                return false;

            return model.Address.Count() == Address.Count() && model.Address.All(addressModel => Address.Contains(addressModel));
        }

        /// <summary>Serves as the default hash function. </summary>
        /// <returns>A hash code for the current object.</returns>
        public override int GetHashCode()
        {
            return ToString().GetHashCode();
        }

        public static bool operator ==(ServiceRoute model1, ServiceRoute model2)
        {
            return Equals(model1, model2);
        }

        public static bool operator !=(ServiceRoute model1, ServiceRoute model2)
        {
            return !Equals(model1, model2);
        }

        #endregion Equality members
    }

/// <summary>
    /// 服务描述符。
    /// </summary>
    [Serializable]
    public class ServiceRouteDescriptor
    {
        /// <summary>
        /// 初始化一个新的服务描述符。
        /// </summary>
        public ServiceRouteDescriptor()
        {
            Metadatas = new Dictionary<string, object>(StringComparer.OrdinalIgnoreCase);
        }

        /// <summary>
        /// 服务Id。
        /// </summary>
        public string Id { get; set; }

        /// <summary>
        /// 访问的令牌
        /// </summary>
        public string Token { get; set; }

        /// <summary>
        /// 路由
        /// </summary>
        public string RoutePath { get; set; }

        /// <summary>
        /// 元数据。
        /// </summary> 
        public IDictionary<string, object> Metadatas { get; set; }

        /// <summary>
        /// 获取一个元数据。
        /// </summary>
        /// <typeparam name="T">元数据类型。</typeparam>
        /// <param name="name">元数据名称。</param>
        /// <param name="def">如果指定名称的元数据不存在则返回这个参数。</param>
        /// <returns>元数据值。</returns>
        public T GetMetadata<T>(string name, T def = default(T))
        {
            if (!Metadatas.ContainsKey(name))
                return def;

            return (T)Metadatas[name];
        }

        #region Equality members

        /// <summary>Determines whether the specified object is equal to the current object.</summary>
        /// <returns>true if the specified object  is equal to the current object; otherwise, false.</returns>
        /// <param name="obj">The object to compare with the current object. </param>
        public override bool Equals(object obj)
        {
            var model = obj as ServiceRouteDescriptor;
            if (model == null)
                return false;

            if (obj.GetType() != GetType())
                return false;

            if (model.Id != Id)
                return false;

            return model.Metadatas.Count == Metadatas.Count && model.Metadatas.All(metadata =>
            {
                object value;
                if (!Metadatas.TryGetValue(metadata.Key, out value))
                    return false;

                if (metadata.Value == null && value == null)
                    return true;
                if (metadata.Value == null || value == null)
                    return false;

                return metadata.Value.Equals(value);
            });
        }

        /// <summary>Serves as the default hash function. </summary>
        /// <returns>A hash code for the current object.</returns>
        public override int GetHashCode()
        {
            return ToString().GetHashCode();
        }

        public static bool operator ==(ServiceRouteDescriptor model1, ServiceRouteDescriptor model2)
        {
            return Equals(model1, model2);
        }

        public static bool operator !=(ServiceRouteDescriptor model1, ServiceRouteDescriptor model2)
        {
            return !Equals(model1, model2);
        }

        #endregion Equality members
    }

Watcher监听器：

子节点监听器：

internal class ChildrenMonitorWatcher : Watcher
    {
        private readonly Task<ZooKeeper> _zooKeeperCall;
        private readonly string _path;
        private readonly Action<string[], string[]> _action;
        private string[] _currentData = new string[0];

        public ChildrenMonitorWatcher(Task<ZooKeeper> zooKeeperCall, string path, Action<string[], string[]> action)
        {
            _zooKeeperCall = zooKeeperCall;
            _path = path;
            _action = action;
        }

        public ChildrenMonitorWatcher SetCurrentData(string[] currentData)
        {
            _currentData = currentData ?? new string[0];

            return this;
        }

        #region Overrides of WatcherBase

        public override async Task process(WatchedEvent watchedEvent)
        {
            if (watchedEvent.getState() != Event.KeeperState.SyncConnected || watchedEvent.getPath() != _path)
                return;
            var zooKeeper = await _zooKeeperCall;
            //Func<ChildrenMonitorWatcher> getWatcher = () => new ChildrenMonitorWatcher(_zooKeeperCall, path, _action);
            Task<ChildrenMonitorWatcher> getWatcher =  Task.Run(() => {return new ChildrenMonitorWatcher(_zooKeeperCall, _path, _action); });
            switch (watchedEvent.get_Type())
            {
                //创建之后开始监视下面的子节点情况。
                case Event.EventType.NodeCreated:
                    await zooKeeper.getChildrenAsync(_path, await getWatcher);
                    break;

                //子节点修改则继续监控子节点信息并通知客户端数据变更。
                case Event.EventType.NodeChildrenChanged:
                    try
                    {
                        var watcher = await getWatcher;
                        var result = await zooKeeper.getChildrenAsync(_path, watcher);
                        var childrens = result.Children.ToArray();
                        _action(_currentData, childrens);
                        watcher.SetCurrentData(childrens);
                    }
                    catch (KeeperException.NoNodeException)
                    {
                        _action(_currentData, new string[0]);
                    }
                    break;

                //删除之后开始监控自身节点，并通知客户端数据被清空。
                case Event.EventType.NodeDeleted:
                    {
                        var watcher = await getWatcher;
                        await zooKeeper.existsAsync(_path, watcher);
                        _action(_currentData, new string[0]);
                        watcher.SetCurrentData(new string[0]);
                    }
                    break;
            }
        }
        #endregion Overrides of WatcherBase
    }

当前节点监听器：

internal class NodeMonitorWatcher : Watcher
    {
        private readonly Task<ZooKeeper> _zooKeeperCall;
        private readonly string _path;
        private readonly Action<byte[], byte[]> _action;
        private byte[] _currentData;

        public NodeMonitorWatcher(Task<ZooKeeper> zooKeeperCall, string path, Action<byte[], byte[]> action)
        {
            _zooKeeperCall = zooKeeperCall;
            _path = path;
            _action = action;
        }

        public NodeMonitorWatcher SetCurrentData(byte[] currentData)
        {
            _currentData = currentData;

            return this;
        }

        #region Overrides of WatcherBase

        public override async Task process(WatchedEvent watchedEvent)
        {
            switch (watchedEvent.get_Type())
            {
                case Event.EventType.NodeDataChanged:
                    var zooKeeper = await _zooKeeperCall;
                    var watcher = new NodeMonitorWatcher(_zooKeeperCall, _path, _action);
                    var data = await zooKeeper.getDataAsync(_path, watcher);
                    var newData = data.Data;
                    _action(_currentData, newData);
                    watcher.SetCurrentData(newData);
                    break;
            }
        }

        #endregion Overrides of WatcherBase
    }

连接断开监听器：

internal class ReconnectionWatcher : Watcher
    {
        private readonly Action _reconnection;

        public ReconnectionWatcher(Action reconnection)
        {
            _reconnection = reconnection;
        }

        #region Overrides of Watcher

        /// <summary>Processes the specified event.</summary>
        /// <param name="watchedEvent">The event.</param>
        /// <returns></returns>
        public override async Task process(WatchedEvent watchedEvent)
        {
            var state = watchedEvent.getState();
            switch (state)
            {
                case Event.KeeperState.Expired:
                case Event.KeeperState.Disconnected:
                    {
                        _reconnection();
                        break;
                    }
            }
            await Task.CompletedTask;
        }

        #endregion Overrides of Watcher
    }