ajax call to .ashx file

Question

Can someone please check why my .ashx file is not firing the alert is being hit fine

function setHeartbeat() {
        setInterval("heartbeat()", 20000); 
           }

         function heartbeat() {
             alert('ajax called');
                 $.ajax({
                     type: "GET",
                     url: "SessionHeartbeat.ashx",
                     data: null,
                     success: function (data) {
                         beatHeart(30);
                         setHeartbeat();

    }});
    }

.ashx file looks like this and is called SessionHeartbeat.ashx

public class SessionHeartbeat : IHttpHandler, IRequiresSessionState
    {
        public bool IsReusable { get { return false; } }

        public void ProcessRequest(HttpContext context)
        {
            context.Session["Heartbeat"] = DateTime.Now;
        }
    }
}

this is my web.config

<httpHandlers>
    <add verb="GET,HEAD" path="SessionHeartbeat.ashx" validate="false" type="SessionHeartbeat"/>
</httpHandlers>

Why don't you provide an `error` function and see what it might tell you? — Crowcoder, Feb 01 '18 at 21:44
I was trying to implement this answer https://stackoverflow.com/questions/1431733/keeping-asp-net-session-open-alive (But couldnt get it to work - I re-did the ajax query in a format I can understand but this doesnt work as well) — AShah, Feb 01 '18 at 21:52
have you registered that handler? are you adding `...` bit into system.web section of web.config? — derloopkat, Feb 01 '18 at 22:00
in `configuration` section add ` ` With that change it worked here. — derloopkat, Feb 01 '18 at 22:12
@derloopkat You don't need to register generic handlers (ashx). That's only neceessary for non-generic handlers, the kind that lacks an ashx file. — mason, Feb 01 '18 at 23:21

score 3 · Accepted Answer · answered Feb 01 '18 at 22:26

If you use handler class, you have to add them to <httpHandlers> tag inside web.config.

What you have is a generic handler. You do not need to do anything, so remove it from <httpHandlers> tag inside web.config.

The following code should work as long as you can access SessionHeartbeat.ashx from client browser.

<script>

    setInterval(function() {
        $.ajax({
            type: "GET",
            url: "<%= ResolveUrl("~/SessionHeartbeat.ashx") %>",
            data: null,
            success: function (data) {
                console.log('Heartbeat called at ' + data);
            }
        });
    }, 20000);

</script>

public class SessionHeartbeat : IHttpHandler, IRequiresSessionState
{
    public void ProcessRequest(HttpContext context)
    {
        var dateTimeNow = DateTime.Now;
        context.Session["Heartbeat"] = dateTimeNow;
        context.Response.Write(dateTimeNow);
    }

    public bool IsReusable { get { return false; } }
}

thank this worked for me fine although I deleted my .ashx file and recreated it and then it started working - you were correct I didn't need it in the web.config file - thanks so much! — AShah, Feb 01 '18 at 22:46

derloopkat · Answer 2 · 2018-02-06T12:36:29.130

The example you mentioned worked after updating web.config:

<configuration>
      <!--Other settings-->
      <system.webServer>
        <validation validateIntegratedModeConfiguration="false"/>
      </system.webServer>
      <system.web>
          <httpHandlers>
             <add verb="GET,HEAD" path="SessionHeartbeat.ashx" validate="false" type="SessionHeartbeat"/>
          </httpHandlers>
      </system.web>
</configuration>

But this depends on IIS version and how it's configured. See this answer: Generic Handler not working on IIS. It explains that a Generic Handler still needs settings in your web.config in some scenarios and that was the case when I've followed the example in the link you posted.

Also I have previously added response write in ProcessRequest

public void ProcessRequest(HttpContext context)
{
    context.Response.Write("Hello World");
    context.Session["Heartbeat"] = DateTime.Now;
}

If you deploy this in IIS you probably will need to register your handler but it was not necessary in my IIS Express.

yes that's being called fine the ajax function is also being called as the alert is firing — AShah, Feb 01 '18 at 21:43

ajax call to .ashx file

2 Answers2