如何使用C# ClientWebSocket读取Azure API Management托管的WebSocket数据？

我正在测试的架构组件如下：

我的目标是通过C#控制台应用的WebSocket客户端，读取由Azure WebPubSub发布到Azure API Management（APIM）的数据。Azure WebPubSub是图中绿色部分的组件，其原生WebSocket端点不对外开放，我通过APIM使用订阅密钥和组织URL将其暴露给外部客户端。

我已借助Azure WebPubSub示例代码实现了直接连接Azure WebPubSub的读写操作，相关代码如下：

直接连接的订阅端代码（AzurePubSubSubscriber） #

using System;
using System.Threading.Tasks;

using Azure.Messaging.WebPubSub;

using Websocket.Client;

namespace subscriber
{
    class Program
    {
        static async Task Main(string[] args)
        {
            var connectionString = "Endpoint=https://pubsub.webpubsub.azure.com;AccessKey=myaccesskey;Version=1.0;";
            var hub = "myhub";

            // 生成客户端访问URL，也可从服务器获取或从门户临时获取
            var serviceClient = new WebPubSubServiceClient(connectionString, hub);
            var url = serviceClient.GetClientAccessUri();

            using (var client = new WebsocketClient(url))
            {
                // 禁用自动断开重连，确保客户端在无数据时保持在线
                client.ReconnectTimeout = null;
                client.MessageReceived.Subscribe(msg => Console.WriteLine($"Message received: {msg}"));
                await client.Start();
                Console.WriteLine("Connected.");
                Console.Read();
            }
        }
    }
}

直接连接的发布端代码（AzurePubSubPublisher） #

using System.Threading.Tasks;
using Azure;
using Azure.Core;
using Azure.Messaging.WebPubSub;

namespace publisher
{
    class Program
    {
        static async Task Main(string[] args)
        {
            await Method1();
        }

        public static async Task Method1()
        {
            var connectionString = $"Endpoint=https://pubsub.webpubsub.azure.com;AccessKey=myaccesskey;Version=1.0;";
            var hub = "myhub";

            while (true)
            {
                Console.WriteLine("Write your message");
                var message = Console.ReadLine();

                if (string.IsNullOrEmpty(message))
                {
                    return;
                }

                // 生成客户端访问URL，也可从服务器获取或从门户临时获取
                var serviceClient = new WebPubSubServiceClient(connectionString, hub);
                await serviceClient.SendToAllAsync(message);
            }
        }
    }
}

但当我通过APIM暴露的端点，使用C#控制台应用的ClientWebSocket读取数据时，无法接收数据，不清楚遗漏了什么配置或代码逻辑。连接APIM端点的客户端代码如下：

连接APIM端点的客户端代码 #

static async Task Main()
{
    await StartWebSocketClient4();
    Console.ReadLine();
}

static async Task StartWebSocketClient4()
{
    try
    {
        Console.Write("Connecting....");
        var cts = new CancellationTokenSource();
        var socket = new ClientWebSocket();
       
        string wsUri = "wss://myorganization.com/sub?subscription-key=ac3529b7619a383dc6ce6e618dbc9b7614a66";

        await socket.ConnectAsync(new Uri(wsUri), cts.Token);
        Console.WriteLine(socket.State);

        await Task.Factory.StartNew(
            async () =>
            {
                var rcvBytes = new byte[1024 * 1024];
                var rcvBuffer = new ArraySegment<byte>(rcvBytes);
                while (true)
                {
                    WebSocketReceiveResult rcvResult = await socket.ReceiveAsync(rcvBuffer, cts.Token);
                    byte[] msgBytes = rcvBuffer.Skip(rcvBuffer.Offset).Take(rcvResult.Count).ToArray();
                    string rcvMsg = Encoding.UTF8.GetString(msgBytes);
                    Console.WriteLine("Received: {0}", rcvMsg);
                }
            }, cts.Token, TaskCreationOptions.LongRunning, TaskScheduler.Default);
    }
    catch(Exception ex)
    {
        Console.WriteLine(ex.Message);
    }
}

内容的提问来源于stack exchange，提问作者Zinov