简单的分布式server 目前分布式系统已经很流行了,一些开源框架也被广泛应用,如dubbo、Motan等。对于一个分布式服务,最基本的一项功能就是服务的注册和发现,而利用zk的EPHEMERAL节点则可以很方便的实现该功能。EPHEMERAL节点正如其名,是临时性的,其生命周期是和客户端会话绑定的,当会话连接断开时,节点也会被删除。下边我们就来实现一个简单的分布式server: server: 服务启动时,创建zk连接,并在go_servers节点下创建一个新节点,节点名为"ip:port",完成服务注册 服务结束时,由于连接断开,创建的节点会被删除,这样client就不会连到该节点 client: 先从zk获取go_servers节点下所有子节点,这样就拿到了所有注册的server 从server列表中选中一个节点(这里只是随机选取,实际服务一般会提供多种策略),创建连接进行通信 这里为了演示,我们每次client连接server,获取server发送的时间后就断开。主要代码如下: server.go ~~~ package main import ( "fmt" "net" "os" "time" "github.com/samuel/go-zookeeper/zk" ) func main() { go starServer("127.0.0.1:8897") go starServer("127.0.0.1:8898") go starServer("127.0.0.1:8899") a := make(chan bool, 1) <-a } func checkError(err error) { if err != nil { fmt.Println(err) } } func starServer(port string) { tcpAddr, err := net.ResolveTCPAddr("tcp4", port) fmt.Println(tcpAddr) checkError(err) listener, err := net.ListenTCP("tcp", tcpAddr) checkError(err) //注册zk节点q // 链接zk conn, err := GetConnect() if err != nil { fmt.Printf(" connect zk error: %s ", err) } defer conn.Close() // zk节点注册 err = RegistServer(conn, port) if err != nil { fmt.Printf(" regist node error: %s ", err) } for { conn, err := listener.Accept() if err != nil { fmt.Fprintf(os.Stderr, "Error: %s", err) continue } go handleCient(conn, port) } fmt.Println("aaaaaa") } func handleCient(conn net.Conn, port string) { defer conn.Close() daytime := time.Now().String() conn.Write([]byte(port + ": " + daytime)) } func GetConnect() (conn *zk.Conn, err error) { zkList := []string{"localhost:2181"} conn, _, err = zk.Connect(zkList, 10*time.Second) if err != nil { fmt.Println(err) } return } func RegistServer(conn *zk.Conn, host string) (err error) { _, err = conn.Create("/go_servers/"+host, nil, zk.FlagEphemeral, zk.WorldACL(zk.PermAll)) return } func GetServerList(conn *zk.Conn) (list []string, err error) { list, _, err = conn.Children("/go_servers") return } ~~~ client.go ~~~ package main import ( "errors" "fmt" "io/ioutil" "math/rand" "net" "time" "github.com/samuel/go-zookeeper/zk" ) func checkError(err error) { if err != nil { fmt.Println(err) } } func main() { for i := 0; i < 100; i++ { startClient() time.Sleep(1 * time.Second) } } func startClient() { // service := "127.0.0.1:8899" //获取地址 serverHost, err := getServerHost() if err != nil { fmt.Printf("get server host fail: %s \n", err) return } fmt.Println("connect host: " + serverHost) tcpAddr, err := net.ResolveTCPAddr("tcp4", serverHost) checkError(err) conn, err := net.DialTCP("tcp", nil, tcpAddr) checkError(err) defer conn.Close() _, err = conn.Write([]byte("timestamp")) checkError(err) result, err := ioutil.ReadAll(conn) checkError(err) fmt.Println(string(result)) return } func getServerHost() (host string, err error) { conn, err := GetConnect() if err != nil { fmt.Printf(" connect zk error: %s \n ", err) return } defer conn.Close() serverList, err := GetServerList(conn) if err != nil { fmt.Printf(" get server list error: %s \n", err) return } count := len(serverList) if count == 0 { err = errors.New("server list is empty \n") return } //随机选中一个返回 r := rand.New(rand.NewSource(time.Now().UnixNano())) host = serverList[r.Intn(3)] return } func GetConnect() (conn *zk.Conn, err error) { zkList := []string{"localhost:2181"} conn, _, err = zk.Connect(zkList, 10*time.Second) if err != nil { fmt.Println(err) } return } func GetServerList(conn *zk.Conn) (list []string, err error) { list, _, err = conn.Children("/go_servers") return } ~~~ 先启动server,可以看到有三个节点注册到zk: ~~~ 127.0.0.1:8897 127.0.0.1:8899 127.0.0.1:8898 2018/08/27 14:04:58 Connected to 127.0.0.1:2181 2018/08/27 14:04:58 Connected to 127.0.0.1:2181 2018/08/27 14:04:58 Connected to 127.0.0.1:2181 2018/08/27 14:04:58 Authenticated: id=100619932030205976, timeout=10000 2018/08/27 14:04:58 Re-submitting `0` credentials after reconnect 2018/08/27 14:04:58 Authenticated: id=100619932030205977, timeout=10000 2018/08/27 14:04:58 Re-submitting `0` credentials after reconnect 2018/08/27 14:04:58 Authenticated: id=100619932030205978, timeout=10000 2018/08/27 14:04:58 Re-submitting `0` credentials after reconnect ~~~ 启动client,可以看到每次client都会随机连接到一个节点进行通信: ~~~ 2018/08/27 14:05:21 Connected to 127.0.0.1:2181 2018/08/27 14:05:21 Authenticated: id=100619932030205979, timeout=10000 2018/08/27 14:05:21 Re-submitting `0` credentials after reconnect 2018/08/27 14:05:21 Recv loop terminated: err=EOF connect host: 127.0.0.1:8899 2018/08/27 14:05:21 Send loop terminated: err=<nil> read tcp 127.0.0.1:54062->127.0.0.1:8899: read: connection reset by peer 127.0.0.1:8899: 2018-08-27 14:05:21.291641 +0800 CST m=+22.480149656 2018/08/27 14:05:22 Connected to [::1]:2181 2018/08/27 14:05:22 Authenticated: id=100619932030205980, timeout=10000 2018/08/27 14:05:22 Re-submitting `0` credentials after reconnect 2018/08/27 14:05:22 Recv loop terminated: err=EOF 2018/08/27 14:05:22 Send loop terminated: err=<nil> connect host: 127.0.0.1:8897 read tcp 127.0.0.1:54064->127.0.0.1:8897: read: connection reset by peer 127.0.0.1:8897: 2018-08-27 14:05:22.302322 +0800 CST m=+23.490801385 2018/08/27 14:05:23 Connected to 127.0.0.1:2181 2018/08/27 14:05:23 Authenticated: id=100619932030205981, timeout=10000 2018/08/27 14:05:23 Re-submitting `0` credentials after reconnect 2018/08/27 14:05:23 Recv loop terminated: err=EOF 2018/08/27 14:05:23 Send loop terminated: err=<nil> connect host: 127.0.0.1:8897 read tcp 127.0.0.1:54070->127.0.0.1:8897: read: connection reset by peer 127.0.0.1:8897: 2018-08-27 14:05:23.312873 +0800 CST m=+24.501324228 2018/08/27 14:05:24 Connected to 127.0.0.1:2181 2018/08/27 14:05:24 Authenticated: id=100619932030205982, timeout=10000 2018/08/27 14:05:24 Re-submitting `0` credentials after reconnect 2018/08/27 14:05:24 Recv loop terminated: err=EOF connect host: 127.0.0.1:8899 2018/08/27 14:05:24 Send loop terminated: err=<nil> read tcp 127.0.0.1:54072->127.0.0.1:8899: read: connection reset by peer 127.0.0.1:8899: 2018-08-27 14:05:24.323668 +0800 CST m=+25.512090155 2018/08/27 14:05:25 Connected to 127.0.0.1:2181 2018/08/27 14:05:25 Authenticated: id=100619932030205983, timeout=10000 2018/08/27 14:05:25 Re-submitting `0` credentials after reconnect 2018/08/27 14:05:25 Recv loop terminated: err=EOF 2018/08/27 14:05:25 Send loop terminated: err=<nil> connect host: 127.0.0.1:8897 read tcp 127.0.0.1:54074->127.0.0.1:8897: read: connection reset by peer 127.0.0.1:8897: 2018-08-27 14:05:25.330257 +0800 CST m=+26.518650566 2018/08/27 14:05:26 Connected to [::1]:2181 2018/08/27 14:05:26 Authenticated: id=100619932030205984, timeout=10000 2018/08/27 14:05:26 Re-submitting `0` credentials after reconnect 2018/08/27 14:05:26 Recv loop terminated: err=EOF 2018/08/27 14:05:26 Send loop terminated: err=<nil> connect host: 127.0.0.1:8897 read tcp 127.0.0.1:54080->127.0.0.1:8897: read: connection reset by peer 127.0.0.1:8897: 2018-08-27 14:05:26.357251 +0800 CST m=+27.545614616 2018/08/27 14:05:27 Connected to 127.0.0.1:2181 2018/08/27 14:05:27 Authenticated: id=100619932030205985, timeout=10000 2018/08/27 14:05:27 Re-submitting `0` credentials after reconnect connect host: 127.0.0.1:8899 2018/08/27 14:05:27 Recv loop terminated: err=EOF 2018/08/27 14:05:27 Send loop terminated: err=<nil> read tcp 127.0.0.1:54082->127.0.0.1:8899: read: connection reset by peer 127.0.0.1:8899: 2018-08-27 14:05:27.369096 +0800 CST m=+28.557430764 2018/08/27 14:05:28 Connected to [::1]:2181 2018/08/27 14:05:28 Authenticated: id=100619932030205986, timeout=10000 2018/08/27 14:05:28 Re-submitting `0` credentials after reconnect 2018/08/27 14:05:28 Recv loop terminated: err=EOF 2018/08/27 14:05:28 Send loop terminated: err=<nil> connect host: 127.0.0.1:8898 read tcp 127.0.0.1:54084->127.0.0.1:8898: read: connection reset by peer 127.0.0.1:8898: 2018-08-27 14:05:28.380455 +0800 CST m=+29.568760988 ...... ~~~ 至此,我们的分布式server就实现了