通过MVC发送服务器发送的事件，同时获得结果和错误 [英] Server-Sent Events via MVC, get simultaneously result and error

问题描述

我试图获得SSE技术并且无法解决一个问题。始终触发两个事件onmessage和错误。我收到了有效日期并同时收到错误消息。为什么会这样，以及如何解决这个问题？如何延长连接的实时时间polltransport request??

这里服务器端

  public class HomeController：Controller 
 {
 public ActionResult Message（）
 {
 JavaScriptSerializer ser = new JavaScriptSerializer（）; 
 var serializedObject = ser.Serialize（new {item =fuck，message =hello}）; 
 var sb = new StringBuilder（）; 
 sb.AppendFormat（data：{0} \ n\ n，serializedObject）; 
 
返回内容（sb.ToString（），text / event-stream）; 
} 
 
 public ActionResult SEEIndex（）
 {
 return View（）; 
} 
} 
  

此处客户端javascript

  $（document）.ready（function（）{
 
 var serverSentEvents = new window.EventSource（'/ Home / Message'） ; // home / message / api / Event 
 
 serverSentEvents.onmessage = function（e）{
 //$ (\"#messages\").append(e.data.item +' < br />'）; 
 var data = JSON.parse（e.data）; 
 console.log（'是的！我们得到它，这是你的数据'，data.item） ; 
}; 
 
 serverSentEvents.onerror = function（e）{
 console.log（'error'）; 
}; 
 
 if（typeof（window.EventSource）！==undefined）{
 console.log（'Yes！Server-sent events support！'）; 
} 
 else {
 console.log（'抱歉！没有服务器发送的事件支持..'）; 
} 
 
}）; 
  

这里的屏幕控制台日志和网络标签<你需要不断写入 Response 对象而不是返回结果：

 使用System.Threading; 
 
 public class HomeController：Controller {
 public ActionResult SEEIndex（）{
 return View（）; 
} 
 public void Message（）{
 Response.ContentType =text / event-stream; 
 do {
 Response.Write（data：understandably\\\
）; 
 Response.Write（data：frustrated\\\
）; 
 Response.Write（\ n）; // double newline表示事件结束
 Response.Flush（）; 
 Thread.Sleep（2000）; //等待2秒再写入
}而（true）
} 
} 
  

返回结果会关闭连接，触发 EventSource.onerror 。

参见< a href =https://stackoverflow.com/a/35678190/111794>这里了解更多细节。

I tried to get SSE technology and couldn't resolve one trouble. Always triggered two event onmessage and error. I have getting valid date and simultaneously error message. Why this happening and how to resolve this ? How to prolong live time of connection "polltransport request" ??

Here server side

  public class HomeController : Controller
        {
            public ActionResult Message() 
            {
                JavaScriptSerializer ser = new JavaScriptSerializer();
                var serializedObject = ser.Serialize(new { item = "fuck", message = "hello" });
                var sb = new StringBuilder();
                sb.AppendFormat("data: {0}\n\n", serializedObject);

                return Content(sb.ToString(), "text/event-stream");
            }

            public ActionResult SEEIndex()
            {
                return View();
            }
        }

Here client javascript

$(document).ready(function () {

    var serverSentEvents = new window.EventSource('/Home/Message');  //home/message   /api/Event

    serverSentEvents.onmessage = function (e) {
        //$("#messages").append(e.data.item + '<br />');
        var data = JSON.parse(e.data);
        console.log('Yes! We get it, here is you data', data.item);
    };

    serverSentEvents.onerror = function (e) {
        console.log('error');
    };

    if (typeof (window.EventSource) !== "undefined") {
        console.log('Yes! Server-sent events support!');
    }
    else {
        console.log('Sorry! No server-sent events support..');
    }

});

Here screens of console log and network tabs in google chrome browser

解决方案

Your server-side code needs to continually write to the Response object instead of returning a result:

using System.Threading;

public class HomeController : Controller {
    public ActionResult SEEIndex() {
        return View();
    }
    public void Message() {
        Response.ContentType = "text/event-stream";
        do {
            Response.Write("data: understandably\n");
            Response.Write("data: frustrated\n");
            Response.Write("\n");     //double newline signals the end of an event
            Response.Flush();
            Thread.Sleep(2000);       //wait 2 seconds before writing again
        } while (true)
    }
}

Returning a result closes the connection, which triggers the EventSource.onerror.

See here for some more details.

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