使用 IServerEvents.NotifyChannel 的缺失事件

Question

我正在尝试使用服务器发送事件向 JS 客户端发送消息。客户仅在每 6 或 7 个事件中获得一次。我做错了什么？

可以使用简单的独立示例重现该行为：

using System;
using System.Threading;

using Funq;
using ServiceStack;

namespace ServerSentEvents
{
    public class AppHost : AppSelfHostBase
    {
        /// <summary>
        /// Default constructor.
        /// Base constructor requires a name and assembly to locate web service classes.
        /// </summary>
        public AppHost()
            : base("ServerSentEvents", typeof(AppHost).Assembly)
        {

        }

        /// <summary>
        /// Application specific configuration
        /// This method should initialize any IoC resources utilized by your web service classes.
        /// </summary>
        /// <param name="container"></param>
        public override void Configure(Container container)
        {
            SetConfig(new HostConfig
            {
#if DEBUG
                DebugMode = true,
                WebHostPhysicalPath = "~/../..".MapServerPath(),
#endif
            });

            container.Register<IServerEvents>(c => new MemoryServerEvents());
            Plugins.Add(new ServerEventsFeature
            {
                OnPublish = (res, msg) =>
                {
                    // Throws an exception
                    //res.Write("\n\n\n\n\n\n\n\n\n\n");  // Force flush: 
                    //res.Flush();
                }
            });

            container.Register(new FrontendMessages(container.Resolve<IServerEvents>()));
        }
    }

    public class FrontendMessage
    {
        public string Level { get; set; }
        public string Message { get; set; }
    }

    public class FrontendMessages
    {
        private readonly IServerEvents _serverEvents;
        private Timer _timer;

        public FrontendMessages(IServerEvents serverEvents)
        {
            if (serverEvents == null) throw new ArgumentNullException(nameof(serverEvents));
            _serverEvents = serverEvents;

            var ticks = 0;
            _timer = new Timer(_ => Info($"Tick {ticks++}"), null, 500, 500);
        }

        public void Info(string message, params object[] parameters)
        {
            var frontendMessage = new FrontendMessage
            {
                Level = "success",
                Message = message
            };

            Console.WriteLine("Sending message: " + frontendMessage.Message);
            _serverEvents.NotifyChannel("messages", frontendMessage);
        }
    }
}

和客户：

<!DOCTYPE html>

<html lang="en" xmlns="http://www.w3.org/1999/xhtml">
<head>
    <meta charset="utf-8" />
    <title></title>
    <script src="js/jquery-1.11.1.min.js"></script>
    <script src="js/ss-utils.js"></script>
</head>
<body>
<script>
    // Handle messages
    var msgSource = new EventSource('event-stream?channel=messages&t=' + new Date().getTime());
    $(msgSource).handleServerEvents({
        handlers: {
            FrontendMessage: function (msg) {
                console.log('Message from server', msg);
            }
        }
    });
</script>
</body>
</html>

控制台日志如下所示：

Message from server Object {Level: "success", Message: "Tick 28"}
Message from server Object {Level: "success", Message: "Tick 35"}
Message from server Object {Level: "success", Message: "Tick 42"}
Message from server Object {Level: "success", Message: "Tick 49"}

Answer 1

问题是您试图在 ServerEventsFeature 注册之前向 IServerEvents 发送消息，因为您是在 AppHost.Configure() 中立即启动它，而不是在 AppHost.Configure() 之后AppHost 已初始化。问题的实际原因是计时器启动时 IdleTimeout 未正确初始化，导致每个服务器事件连接的生命周期为 00:00:00，这意味着它们会收到一条消息自动处理并再次自动重新连接 - 整个过程大约需要 6-7 个 ticks :)

ServiceStack Plugins aren't registered when they're added, they get registered together after AppHost.Configure() which gives other plugins a chance to add/remove/inspect other plugins before they're registered. You also don't need to register MemoryServerEvents since that's the default and the recommended way to initialize a timer with an interval是在定时器回调中使用timer.Change()。

鉴于此，我会将您的 AppHost 重写为：

public class AppHost : AppSelfHostBase
{
    public AppHost()
        : base("ServerSentEvents", typeof(AppHost).Assembly) { }

    public override void Configure(Container container)
    {
        SetConfig(new HostConfig {
#if DEBUG
            DebugMode = true,
            WebHostPhysicalPath = "~/../..".MapServerPath(),
#endif
        });

        Plugins.Add(new ServerEventsFeature());
        container.Register(c => new FrontendMessages(c.Resolve<IServerEvents>()));
    }
}

并让您的 FrontendMessages 仅在显式调用 Start() 时启动，即：

public class FrontendMessage
{
    public string Level { get; set; }
    public string Message { get; set; }
}

public class FrontendMessages
{
    private readonly IServerEvents _serverEvents;
    private Timer _timer;

    public FrontendMessages(IServerEvents serverEvents)
    {
        if (serverEvents == null) throw new ArgumentNullException(nameof(serverEvents));
        _serverEvents = serverEvents;
    }

    public void Start()
    {
        var ticks = 0;
        _timer = new Timer(_ => {
            Info($"Tick {ticks++}");
            _timer.Change(500, Timeout.Infinite);
        }, null, 500, Timeout.Infinite);
    }

    public void Info(string message, params object[] parameters)
    {
        var frontendMessage = new FrontendMessage {
            Level = "success",
            Message = message
        };

        Console.WriteLine("Sending message: " + frontendMessage.Message);
        _serverEvents.NotifyChannel("messages", frontendMessage);
    }
}

然后在AppHost初始化完成后才启动，即：

class Program
{
    static void Main(string[] args)
    {
        var appHost = new AppHost()
            .Init()
            .Start("http://*:2000/"); //Start AppSelfHost

        appHost.Resolve<FrontendMessages>().Start(); //Start timer

        Process.Start("http://localhost:2000/"); //View in Web browser
        Console.ReadLine();  //Prevent Console App from existing
    }
}

使用 IServerEvents.NotifyChannel 的缺失事件

Missing events using IServerEvents.NotifyChannel

servicestack

server-sent-events