PushSharp 关注点分离

Question

我目前正在开发一个 C# Web 应用程序，我正在尝试使用 PushSharp 包来获取推送通知。我在项目的 Global.asax 文件中有所有用于推送通知的代码，但我不断收到错误消息：

The collection has been marked as complete with regards to additions.

这是我的 Global.asax 文件：

using BYC.Models;
using BYC.Models.Enums;
using Newtonsoft.Json.Linq;
using PushSharp.Apple;
using PushSharp.Google;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Cryptography.X509Certificates;
using System.Web.Http;
using System.Web.Mvc;
using System.Web.Optimization;
using System.Web.Routing;

namespace BYC
{
    public class WebApiApplication : System.Web.HttpApplication
    {

        protected void Application_Start()
        {
            AreaRegistration.RegisterAllAreas();
            GlobalConfiguration.Configure(WebApiConfig.Register);
            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            BundleConfig.RegisterBundles(BundleTable.Bundles);
        }
        protected void Application_End()
        {
            PushBrokerSingleton pbs = new PushBrokerSingleton();
            pbs.SendQueuedNotifications();
        }
    }

    public sealed class PushBrokerSingleton
    {
        private static ApnsServiceBroker Apns { get; set; }
        private static GcmServiceBroker Gcm { get; set; }
        private static bool ApnsStarted = false;
        private static bool GcmStarted = false;
        private static object AppleSyncVar = new object();
        private static object GcmSyncVar = new object();

        private static readonly log4net.ILog log = log4net.LogManager.GetLogger
(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);

        public PushBrokerSingleton()
        {
            if (Apns == null)
        {
            string thumbprint = (AppSettings.Instance["APNS:Thumbprint"]);
            X509Store store = new X509Store(StoreName.My, StoreLocation.CurrentUser);
            store.Open(OpenFlags.OpenExistingOnly | OpenFlags.ReadOnly);

            ApnsConfiguration.ApnsServerEnvironment production = Convert.ToBoolean(AppSettings.Instance["APNS:Production"]) ?
                ApnsConfiguration.ApnsServerEnvironment.Production : ApnsConfiguration.ApnsServerEnvironment.Sandbox;

            X509Certificate2 appleCert = store.Certificates
              .Cast<X509Certificate2>()
              .SingleOrDefault(c => string.Equals(c.Thumbprint, thumbprint, StringComparison.OrdinalIgnoreCase));


            ApnsConfiguration apnsConfig = new ApnsConfiguration(production, appleCert);
            Apns = new ApnsServiceBroker(apnsConfig);
            Apns.OnNotificationFailed += (notification, aggregateEx) => {

                aggregateEx.Handle(ex => {

                    // See what kind of exception it was to further diagnose
                    if (ex is ApnsNotificationException)
                    {
                        var notificationException = ex as ApnsNotificationException;

                        // Deal with the failed notification
                        var apnsNotification = notificationException.Notification;
                        var statusCode = notificationException.ErrorStatusCode;

                        log.Error($"Notification Failed: ID={apnsNotification.Identifier}, Code={statusCode}");

                    }
                    else {
                        // Inner exception might hold more useful information like an ApnsConnectionException           
                        log.Error($"Notification Failed for some (Unknown Reason) : {ex.InnerException}");
                    }

                    // Mark it as handled
                    return true;
                });
            };

            Apns.OnNotificationSucceeded += (notification) => {
                log.Info("Notification Successfully Sent to: " + notification.DeviceToken);
            };
        }
        if(Gcm == null)
        {
            GcmConfiguration gcmConfig = new GcmConfiguration(AppSettings.Instance["GCM:Token"]);
            Gcm = new GcmServiceBroker(gcmConfig);
        }
    }

    public bool QueueNotification(Notification notification, Device device)
    {
        if (!ApnsStarted)
        {
            ApnsStarted = true;
            lock (AppleSyncVar)
            {
                Apns.Start();
            }
        }
        if(!GcmStarted)
        {
            GcmStarted = true;
            lock (GcmSyncVar)
            {
                Gcm.Start();
            }
        }
        switch (device.PlatformType)
        {
            case PlatformType.iOS:
                return QueueApplePushNotification(notification, device.PushRegistrationToken);
            case PlatformType.Android:
                return QueueAndroidPushNotification(notification, device.PushRegistrationToken);
            default: return false;
        }
    }

    private bool QueueApplePushNotification(Notification notification, string pushNotificationToken)
    {
        string appleJsonFormat = "{\"aps\": {\"alert\":" + '"' + notification.Subject + '"' + ",\"sound\": \"default\", \"badge\": " + notification.BadgeNumber + "}}";
        lock (AppleSyncVar)
        {
            Apns.QueueNotification(new ApnsNotification()
            {
                DeviceToken = pushNotificationToken,
                Payload = JObject.Parse(appleJsonFormat)
            });
        }
        return true;
    }

    private bool QueueAndroidPushNotification(Notification notification, string pushNotificationToken)
    {
        string message = "{\"alert\":\"" + notification.Subject + "\",\"badge\":" + notification.BadgeNumber + "\"}";
        lock (GcmSyncVar)
        {
            Gcm.QueueNotification(new GcmNotification()
            {
                RegistrationIds = new List<string>
                         {
                             pushNotificationToken
                         },
                Data = JObject.Parse(message),
                Notification = JObject.Parse(message)
            });
        }
        return true;
    }

    public void SendQueuedNotifications()
    {
        if(Apns != null)
        {
            if (ApnsStarted)
            {
                lock(AppleSyncVar){
                    Apns.Stop();
                    log.Info("Sent Apns Notifications");
                    ApnsStarted = false;
                }
            }
        }
        if(Gcm != null)
        {
            if (GcmStarted)
            {
                lock (GcmSyncVar)
                {
                    Gcm.Stop();
                    log.Info("Sent Gcm Notifications");
                    GcmStarted = false;
                }
            }
        }
    }
}

}

Answer 1

当您尝试重用已调用 Stop() 的服务代理实例（例如：ApnsServiceBroker）时，就会发生这种情况。

我猜你的 Application_End 在某个时候被调用并且 Application_Start 被再次调用，但是因为 PushBrokerSingleton.Apns 不是空的（它是一个静态字段所以它必须存在即使应用程序有 stopped/started)，它也永远不会被重新创建。

PushSharp 很难与 ASP.NET 模式一起很好地工作，某种服务守护进程会更好。

主要问题是您的应用可能会在您不希望的情况下被回收或终止。同一个应用程序中的不相关请求可能会导致您的进程中断，或者您的 AppDomain 可能会被拆除。如果发生这种情况并且代理的 Stop() 调用无法成功结束，一些排队的消息可能会丢失。这是一篇关于一些警告的好文章：http://haacked.com/archive/2011/10/16/the-dangers-of-implementing-recurring-background-tasks-in-asp-net.aspx/ 实际上，这可能不是什么大问题，您当然可以减轻其中的一部分，但请记住这一点。

说了这么多，我认为一个简单的解决方法是在 Application_Start 中创建 PushBrokerSingleton.Apns 和 PushBrokerSingleton.Gcm 的新实例。这可能会给您带来其他问题，所以我不确定它是否是 正确的 修复，但它会解决在 [=11= 之后不打算重用代理的问题] 已被调用。

我也会考虑为 'reset' 集合添加一些方法。我不确定在 .Stop() 结束后自动执行此操作是否是个好主意，但我可能会考虑添加 .Reset() 或类似的方法来实现此目的。无论如何，现在创建一个新的代理实例是完全可以接受的。

PushSharp 关注点分离

PushSharp Separation of Concerns

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