之前的文章介绍过Asp.net SignalR,  ASP .NET SignalR是一个ASP .NET 下的类库，可以在ASP .NET 的Web项目中实现实时通信.  今天我们来实现服务端消息推送到Web端,   首先回顾一下它抽象层次图是这样的:

实际上 Asp.net SignalR 2 实现 服务端消息推送到Web端, 更加简单. 为了获取更好的可伸缩性, 我们引入消息队列, 看如下基本流程图:

消息队列MQ监听, 在Web site 服务端一收到消息,马上通过Signalr 推送广播到客户端.  创建ASP.NET MVC WEB APP,  从NuGet 安装SignalR 2.12

Install-Package Microsoft.AspNet.SignalR

具体实现代码,是这样的,我们增加一个空的Hub:

    public class FeedHub : Hub

    {

        public void Init()

        {

        }

    }

是简单的消息模型, 标题与正文属性: 

    [Serializable]

    public class PushMessageModel

    {

        public int Id { get; set; }

        public string MSG_TITLE { get; set; }

        public string MSG_CONTENT { get; set; }

    }

服务端推送具体类,记录日志, 创建消息队列实例,监听, 等待收取消息. 这里我们使用的是AcitveMQ的.net客户端. ActiveMQListenAdapter是一个封装过的对象. 

    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("从MQ收到消息{0}", m.MSG_CONTENT);

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

            };

            activemq.ReceviceListener<PushMessageModel>();

        }

    }

上面有一句关键代码GlobalHost.ConnectionManager.GetHubContext<FeedHub>().Clients.All.receive(m);  这里使用了GetHubContext方法后,直接来广播消息.

需要在MVCApplication下加载:

    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();

        }

    }

同时需要增加一个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();

        }

    }

}

接下来是客户端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 具体与SignalR.js通信, 创建名为receive的function, 与服务端对应

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-;

            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代码与服务端有通信, 具体看如下图:

        在Index.cshtml,  我们需要引用SignalR客户端JS, 放置hubs, 这里我们使用了jsrender,  easyui.js 来呈现推送的消息.

@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>

上代码服务端引用js的Script.Render, 需要在BundleConfig.cs中加入以下代码:

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

同时我们构建一个WebAPI来发送需要推送的消息, 片断代码:

        /// <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("发送成功！");

                    return Ok();

                }

                else

                {

                    log.ErrorFormat("发送失败！{0}", messagemodel);

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

                }

            }

            else

            {

                log.ErrorFormat("参数验证失败！{0}", messagemodel);

                return Content(HttpStatusCode.BadRequest, ModelState);

            }

        }

发送消息到ActiveMQ的关键代码:

    public class MessageRepository:IMessageRepository

    {

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

        /// <summary>

        /// 发送消息

        /// </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;

        }

    }

如果您需要运行DEMO程序,需要构建基于ActiveMQ的消息队列,   运行效果是这样的, 我们在一个静态html中, 发送一个ajax到webapi服务端,  发送后

另一个website网站收到后, 列表更新, 并在右下角弹出框

IE的控制台输出:

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'.

上面粗体是 最后我们发的第5条信息控制台的输出.

好了,到这儿, 由于篇幅有限, 示例代码没有全部展示, 可以在这儿下载,  需要安装ActiveMQ