.Net Core SignalR - 连接超时 - 检测信号计时器 - 连接状态更改处理

在 IIS 后面运行 SignalR Core 时，这是一个问题。IIS 将在 2 分钟后关闭空闲连接。长期计划是添加保持活动状态的消息，作为副作用，这将阻止 IIS 关闭连接。若要暂时解决此问题，可以：

• 定期向客户端发送消息
• 更改 IIS 中的空闲超时设置，如此处所述
• 如果连接关闭，请在客户端重新启动连接
• 使用不同的传输方式（例如，由于您不能在 IIS 后面的 Win7/Win2008 R2 上使用 webSockets，因此需要长时间轮询）

我现在有一个有效的解决方案（到目前为止在 Chrome 和 FF 中进行了测试）。为了激励你想出更好的东西，或者在你自己想出这样的东西时节省一点时间，我在这里发布我的解决方案：

Heartbeat-“Tick”消息（服务器例行 ping 客户端）在上面的问题中进行了描述。 客户端（“Tock”部分）现在具有：

• 一个用于注册连接的函数，以便可以重复回调方法（connection.on（））;否则，在重新启动“新 HubConnection”后，它们就会丢失
• 用于注册 TockTimer 的函数
• 以及实际发送 Tock ping 的函数

tock 方法在发送时捕获错误，并尝试启动新连接。由于计时器一直在运行，我正在注册一个新连接，然后只需坐下来等待下一次调用。 将客户放在一起：

// keeps the connection object
var connection = null;
// stores the ID from SetInterval
var heartBeatTockTimer = 0;
// how often should I "tock" the server
var heartBeatTockTimerSeconds = 10;
// how often should I retry after connection loss?
var maxRetryAttempt = 5;
// the retry should wait less long then the TockTimer, or calls may overlap
var retryWaitSeconds = heartBeatTockTimerSeconds / 2;
// how many retry attempts did we have?
var currentRetryAttempt = 0;
// helper function to wait a few seconds
$.wait = function(miliseconds) {
    var defer = $.Deferred();
    setTimeout(function() { defer.resolve(); }, miliseconds);
    return defer;
};
// first routine start of the connection
registerSignalRConnection();
function registerSignalRConnection() {
    ++currentRetryAttempt;
    if (currentRetryAttempt > maxRetryAttempt) {
        console.log("Clearing registerHeartBeatTockTimer");
        clearInterval(heartBeatTockTimer);
        heartBeatTockTimer = 0;
        throw "Retry attempts exceeded.";
    }
    if (connection !== null) {
        console.log("registerSignalRConnection was not null", connection);
        connection.stop().catch(err => console.log(err));
    }
    console.log("Creating new connection");
    connection = new signalR.HubConnection("/signalr", { transport: signalR.TransportType.ServerSentEvents });
    connection.on("Heartbeat", serverTime => { console.log(serverTime); });
    connection.start().then(() => {
        console.log("Connection started, starting timer.");
        registerHeartBeatTockTimer();
    }).catch(exception => {
        console.log("Error connecting", exception, connection);
    });
}
function registerHeartBeatTockTimer() {
    // make sure we're registered only once
    if (heartBeatTockTimer !== 0) return;
    console.log("Registering registerHeartBeatTockTimer");
    if (connection !== null)
        heartBeatTockTimer = setInterval(sendHeartBeatTock, heartBeatTockTimerSeconds * 1000);
    else
        console.log("Connection didn't allow registry");
}

function sendHeartBeatTock() {
    console.log("Standard attempt HeartBeatTock");
    connection.invoke("HeartBeatTock").then(() => { 
         console.log("HeartbeatTock worked.") })
         .catch(err => {
             console.log("HeartbeatTock Standard Error", err);
             $.wait(retryWaitSeconds * 1000).then(function() {
                 console.log("executing attempt #" + currentRetryAttempt.toString());
             registerSignalRConnection();
         });
         console.log("Current retry attempt: ", currentRetryAttempt);
     });
 }

基于 ExternalUse 答案的客户端版本...

import * as signalR from '@aspnet/signalr'
import _ from 'lodash'

var connection = null;
var sendHandlers = [];
var addListener = f => sendHandlers.push(f);

function registerSignalRConnection() {

    if (connection !== null) {
        connection.stop().catch(err => console.log(err));
    }

    connection = new signalR.HubConnectionBuilder()
        .withUrl('myHub')
        .build();

    connection.on("Heartbeat", serverTime =>
        console.log("Server heartbeat: " + serverTime));

    connection.on("Send", data =>
        _.each(sendHandlers, value => value(data)));

    connection.start()
        .catch(exception =>
            console.log("Error connecting", exception, connection));
}

registerSignalRConnection();

setInterval(() =>
    connection.invoke("HeartBeatTock")
        .then(() => console.log("Client heatbeat."))
        .catch(err => {    
            registerSignalRConnection();
        }), 10 * 1000);

export { addListener };