之前的文章介紹過asp.net SignalR,  ASP .NET SignalR是一個ASP .NET 下的類庫，可以在ASP .NET 的Web項目中實現實時通信.  今天我們來實現服務端消息推送到Web端,   首先回顧一下它抽象層次圖是這樣的:

實際上 Asp.net SignalR 2 實現 服務端消息推送到Web端, 更加簡單. 為了獲取更好的可伸縮性, 我們引入消息隊列, 看如下基本流程圖:

消息隊列MQ監聽, 在Web site 服務端一收到消息,馬上通過Signalr 推送廣播到客戶端.  創建ASP.NET MVC WEB APP,  從NuGet 安裝SignalR 2.12

Install-Package Microsoft.AspNet.SignalR

具體實現代碼,是這樣的,我們增加一個空的Hub:

    public class FeedHub : Hub

    {

        public void Init()

        {

        }

    }

是簡單的消息模型, 標題與正文屬性:

    [Serializable]

    public class PushMessageModel

    {

        public int Id { get; set; }

        public string MSG_TITLE { get; set; }

        public string MSG_CONTENT { get; set; }

    }

服務端推送具體類,記錄日志, 創建消息隊列實例,監聽, 等待收取消息. 這里我們使用的是AcitveMQ的.net客戶端. ActiveMQListenAdapter是一個封裝過的對象. 

    public class MQHubsConfig

    {

        private static ILogger log = new Logger("MQHubsConfig");

        /// <summary>

        /// Registers the mq listen and hubs.

        /// </summary>

        public static void RegisterMQListenAndHubs()

        {

            var activemq = Megadotnet.MessageMQ.Adapter.ActiveMQListenAdapter<PushMessageModel>.Instance(MQConfig.MQipAddress, MQConfig.QueueDestination);

            activemq.MQListener += m =>

            {

                log.InfoFormat("從MQ收到消息{0}", m.MSG_CONTENT);

                GlobalHost.ConnectionManager.GetHubContext<FeedHub>().Clients.All.receive(m);

            };

            activemq.ReceviceListener<PushMessageModel>();

        }

    }

上面有一句關鍵代碼GlobalHost.ConnectionManager.GetHubContext<FeedHub>().Clients.All.receive(m);  這里使用了GetHubContext方法后,直接來廣播消息.

需要在MVCapplication下加載:

    public class MvcApplication : System.Web.HttpApplication

    {

        protected void Application_Start()

        {

            AreaRegistration.RegisterAllAreas();

            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);

            RouteConfig.RegisterRoutes(RouteTable.Routes);

            BundleConfig.RegisterBundles(BundleTable.Bundles);

            MQHubsConfig.RegisterMQListenAndHubs();

        }

    }

同時需要增加一個Starup.cs, 用于Owin

[assembly: OwinStartup(typeof(RealTimeApp.Startup))]

namespace RealTimeApp

{

    public class Startup

    {

        public void Configuration(IAppBuilder app)

        {

            // Any connection or hub wire up and configuration should go here

            app.MapSignalR();

        }

    }

}

接下來是客戶端App.js:

function App() {

    var init = function () {

        Feed();

        $.connection.hub.logging = true;

        $.connection.hub.start()

            .done(function() {

                console.log("Connected!");

                $(document).trigger("Connected");

            })

            .fail(function() { console.log("Could not Connect!"); });

    };

    init();

};

Feed.js 具體與SignalR.js通信, 創建名為receive的function, 與服務端對應

function Feed() {

    var chat = undefined;

    var init = function () {

        // Reference the auto-generated proxy for the hub.

        chat = $.connection.feedHub;

        // Create a function that the hub can call back to display messages.

        chat.client.receive = function (item) {

            var selector = "ul.feed-list li[data-id=" + item.Id + "]";

            if (!($(selector).length > 0)) {

                $("ul.feed-list").prepend($(".feed-template").render(item));

                $("ul.feed-list li:gt(3)").remove();

            }

            $.messager.show({

                title: 'Tips',

                msg: item.MSG_CONTENT,

                showType: 'show'          

            });

        };

        // Start the connection.

        $.connection.hub.start().done(function () {

            chat.server.init();

        });

    };

    init();

};

        上面的javascript代碼與服務端有通信, 具體看如下圖:

        在Index.cshtml,  我們需要引用SignalR客戶端JS, 放置hubs, 這里我們使用了jsrender,  easyui.js 來呈現推送的消息.

@model dynamic

@section Scripts {

<link href="/Content/themes/default/window.CSS" rel="stylesheet" />

<link href="~/Content/themes/default/progressbar.css" rel="stylesheet" />

<link href="~/Content/themes/default/linkbutton.css" rel="stylesheet" />

<script src="~/Scripts/jquery.signalR-2.1.2.min.js"></script>

<!--Reference the autogenerated SignalR hub script. -->

<script src="~/signalr/hubs"></script>

<script src="~/Scripts/jsrender.js"></script>

<script src="~/Scripts/jquery.easyui.min-1.4.1.js"></script>

@Scripts.Render("~/Scripts/project.js")

    <script type="text/Javascript">

        $(document).ready(function () {

            var app = new App();

        });

    </script>

}

<div class="row-fluid">

    <div class="span8">

        <div class="widget">

            <div class="widget-header">

                <h2>Feed</h2>

            </div>

            <div class="widget-content">

                <ul class="span12 feed-list"></ul>

            </div>

        </div>

    </div>

</div>

<script class="chat-template" type="text/x-jquery-tmpl">

    <li>

        <p>{{>Message}}</p>

    </li>

</script>

<script class="feed-template" type="text/x-jquery-tmpl">

    <li data-id="{{>Id}}">

        <div class="row-fluid">

            <div class="span8">

                <h3>{{>MSG_CONTENT}}</h3>

            </div>

        </div>

    </li>

</script>

上代碼服務端引用js的Script.Render, 需要在BundleConfig.cs中加入以下代碼:

          bundles.Add(new ScriptBundle("~/Scripts/project.js")              .IncludeDirectory("~/Scripts/Project", "*.js", false));

同時我們構建一個WebAPI來發送需要推送的消息, 片斷代碼:

        /// <summary>

        /// SendMessage

        /// </summary>

        /// <param name="messagemodel">The messagemodel.</param>

        /// <returns></returns>

        [HttpPost]

        public IHttpActionResult SendMessage(PushMessageModel messagemodel)

        {

            return SendToServer(messagemodel);

        }

        /// <summary>

        /// Sends to server.

        /// </summary>

        /// <param name="messagemodel">The messagemodel.</param>

        /// <returns></returns>

        private IHttpActionResult SendToServer(PushMessageModel messagemodel)

        {

            if (ModelState.IsValid)

            {

                if (messageRepository.SendMessage(messagemodel))

                {

                    log.Debug("發送成功！");

                    return Ok();

                }

                else

                {

                    log.ErrorFormat("發送失??！{0}", messagemodel);

                    return Content(HttpStatusCode.ExpectationFailed, new Exception("send message error"));

                }

            }

            else

            {

                log.ErrorFormat("參數驗證失??！{0}", messagemodel);

                return Content(HttpStatusCode.BadRequest, ModelState);

            }

        }

發送消息到ActiveMQ的關鍵代碼:

    public class MessageRepository:IMessageRepository

    {

        private static ILogger log = new Logger("MessageRepository");

        /// <summary>

        /// 發送消息

        /// </summary>

        /// <param name="messagemodel"></param>

        /// <returns></returns>

        public bool SendMessage(PushMessageModel messagemodel)

        {

          var activemq = new ActiveMQAdapter<PushMessageModel>(MQConfig.MQIpAddress, MQConfig.QueueDestination);

          return activemq.SendMessage<PushMessageModel>(messagemodel)>0;

        }

    }

如果您需要運行DEMO程序,需要構建基于ActiveMQ的消息隊列,   運行效果是這樣的, 我們在一個靜態html中, 發送一個Ajax到webapi服務端,  發送后

另一個website網站收到后, 列表更新, 并在右下角彈出框

IE的控制臺輸出:

HTML1300: Navigation occurred.
File: Index
[11:05:25 GMT+0800 (China Standard Time)] SignalR: Client subscribed to hub 'feedhub'.
[11:05:25 GMT+0800 (China Standard Time)] SignalR: Negotiating with '/signalr/negotiate?clientProtocol=1.4&connectionData=%5B%7B%22name%22%3A%22feedhub%22%7D%5D'.
[11:05:25 GMT+0800 (China Standard Time)] SignalR: This browser doesn't support SSE.
[11:05:25 GMT+0800 (China Standard Time)] SignalR: Binding to iframe's load event.
[11:05:25 GMT+0800 (China Standard Time)] SignalR: Iframe transport started.
[11:05:25 GMT+0800 (China Standard Time)] SignalR: foreverFrame transport selected. Initiating start request.
[11:05:25 GMT+0800 (China Standard Time)] SignalR: The start request succeeded. Transitioning to the connected state.
[11:05:25 GMT+0800 (China Standard Time)] SignalR: Now monitoring keep alive with a warning timeout of 13333.333333333332 and a connection lost timeout of 20000.
[11:05:25 GMT+0800 (China Standard Time)] SignalR: Invoking feedhub.Init
Connected!
[11:05:25 GMT+0800 (China Standard Time)] SignalR: Invoked feedhub.Init
[11:07:12 GMT+0800 (China Standard Time)] SignalR: Triggering client hub event 'receive' on hub 'FeedHub'.
[11:07:18 GMT+0800 (China Standard Time)] SignalR: Triggering client hub event 'receive' on hub 'FeedHub'.
[11:07:32 GMT+0800 (China Standard Time)] SignalR: Triggering client hub event 'receive' on hub 'FeedHub'.
[11:07:51 GMT+0800 (China Standard Time)] SignalR: Triggering client hub event 'receive' on hub 'FeedHub'.
[11:09:25 GMT+0800 (China Standard Time)] SignalR: Triggering client hub event 'receive' on hub 'FeedHub'.

上面粗體是 最后我們發的第5條信息控制臺的輸出.

好了,到這兒, 由于篇幅有限, 示例代碼沒有全部展示, 可以在這兒下載,  需要安裝ActiveMQ

希望對您開發實時Web App有幫助.

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SignalR介紹與Asp.net

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作者：Petter Liu
出處：http://m.survivalescaperooms.com/wintersun/
本文版權歸作者和博客園共有，歡迎轉載，但未經作者同意必須保留此段聲明，且在文章頁面明顯位置給出原文連接，否則保留追究法律責任的權利。
該文章也同時發布在我的獨立博客中-Petter Liu Blog。