c# - SignalR 2 StartAsync 永远不会返回

Question

在类的后续部分中，StartAsync 永远不会返回。

有什么想法吗？服务器似乎工作正常，并且可以与 Javascript 客户端一起使用。

SignalR 客户端版本为 v1.0.0-rc1-final

    public HubUtil(string baseUrl) //string clientId
    {
        connection = new HubConnectionBuilder()
            .AddJsonProtocol()
            .WithUrl(baseUrl)  // baseUrl is "https://hostname/hubname"
            .Build();

        connection.Closed += Connection_Closed;
        StartIfNeededAsync();
    }

    private Task Connection_Closed(Exception arg)
    {
        return StartIfNeededAsync();
    }

    public async Task StartIfNeededAsync()
    {
        if (_connectionState == ConnectionState.Connected)
        {
            return;
        }

        try
        {
            await connection.StartAsync(); // Never connects
            _connectionState = ConnectionState.Connected;
        }
        catch (Exception ex)
        {
            _connectionState = ConnectionState.Faulted;
            throw;
        }
    }

在基本的控制台应用程序中 hubutil 是这样调用的:

    static void Main(string[] args)
    {
        var hub = new HubUtil("https://host/hubname");
        hub.Invoke("checkin", "id", "");
    }

Answer 1

可能试图同时做太多事情。

从构造函数中删除 StartIfNeededAsync

public HubUtil(string baseUrl) {
    connection = new HubConnectionBuilder()
        .AddJsonProtocol()
        .WithUrl(baseUrl)  // baseUrl is "https://hostname/hubname"
        .Build();

    connection.Closed += Connection_Closed;       
}

private Task Connection_Closed(Exception arg) {
    return StartIfNeededAsync();
}

public async Task StartIfNeededAsync() {
    if (_connectionState == ConnectionState.Connected) {
        return;
    }

    try {
        await connection.StartAsync();
        _connectionState = ConnectionState.Connected;
    } catch (Exception ex) {
        _connectionState = ConnectionState.Faulted;
        throw;
    }
}

//...

并使其成为显式调用，同时考虑 SSL。

//Handle TLS protocols
System.Net.ServicePointManager.SecurityProtocol =
    System.Net.SecurityProtocolType.Tls
    | System.Net.SecurityProtocolType.Tls11
    | System.Net.SecurityProtocolType.Tls12;

var hub = new HubUtil("https://host/hubname");
await hub.StartIfNeededAsync();
hub.Invoke("checkin", "id", "");