Microsoft.XMLHTTP and javascript under IE6

jeff1974 · October 23rd, 2004, 08:32 AM

Hello,

I use a check tool in a Javascript to get the HTTP status (200, 404, etc...) of severals pages (http://@IP/une_page.htm) in the to print it in a html page. This is working client side. Here is my code :

function checkURLStatus(url)
{
    var http = new ActiveXObject('Microsoft.XMLHTTP'); // or Msxml2.XMLHTTP.3.0
    http.open('HEAD', url, true); // Asynchronous request
    try
    {
        http.send();
        do
        {
            ... loop for response timeout ...
        }
        while(http.readyState != 4);
    }
    catch(erreur)
    {
        return 'Err';
    }
    return (http.status);
}

This used to work under IE5.x but it doesn't with IE6 (v6.0.2600).
The readyState always keep the value 1.

A synchronous request (false instead of true) works but if the requested server is down IE freezes about 20 seconds.

If someone have any idea ?

JFB

joefawcett · October 23rd, 2004, 10:48 AM

Works okay on my machine except it can take a while, what are you doing in the waiting loop?
In my opinion you are better off doing a true asynchronous call, try this example:

Code:

<html>
<head>
<title>Test URL</title>

<script type="text/Jscript">
  function checkURLStatus(url)
  {
      var http = new ActiveXObject('Msxml2.XMLHTTP.3.0'); // or ActiveXObject('Microsoft.XMLHTTP')
      http.open('HEAD', url, true); // Asynchronous request
      try
      {    
          http.send();
          do
          {
            for (var i = 0; i < 10000000; i++)
            {
              var a = i;
            }
          }
          while(http.readyState != 4);
      }
      catch(e)
      {
          return e.message;
      }
      return (http.getAllResponseHeaders());
  }

  function checkURLStatusAsync(url)
  {
      asyncHttp = new ActiveXObject('Msxml2.XMLHTTP.3.0');
      asyncHttp.open('HEAD', url, true); // Asynchronous request
      asyncHttp.onreadystatechange = checkReadyState;
      try
      {    
          asyncHttp.send();
      }
      catch(e)
      {
          return e.message;
      }
  }

  function checkReadyState()
  {
    var iState = asyncHttp.readyState;
    showData("Ready state: " + iState, true);
    if (iState == 4)
    {
      showData(asyncHttp.getAllResponseHeaders(), true);      
    }
  }

  function showData(Data, Append)
  {
    var oOutput = document.getElementById("txtResults");
    if (Append)
    {
      oOutput.value += Data + "\n";
    }
    else
    {
      oOutput.value = Data;
    }

  }

  function testUrlAsync(Url)
  {
    checkURLStatusAsync(Url);
  }

  function testUrl(Url)
  {    
    var sResult = checkURLStatus(Url);
    showData(sResult);
  }
</script>
</head>
<body>
<input type="text" size="40" value="http://www.google.com" id="txtUrl">
<input type="button" onclick="testUrl(txtUrl.value);" value="Test URL">&nbsp;&nbsp;
<input type="button" onclick="testUrlAsync(txtUrl.value);" value="Test URL async">
<br>
<textarea rows="30" cols="60" id="txtResults"></textarea>

</body>
</html>

--

Joe (Co-author Beginning XML, 3rd edition)

jeff1974 · October 23rd, 2004, 05:06 PM

Thanks Joe for your answer, it works at my home too.
You wanted to know all my code, here it is and I thik it is the problem :

function checkURLStatus(url)
{
    var http = new ActiveXObject('Microsoft.XMLHTTP');
    http.open('HEAD', url, true);
    try
    {
        http.send();
        var timeout = 4000; // 4 seconds
        var date = new Date();
        var start = date.getTime();
        do
        {
            var date = new Date();
            var now = date.getTime();
            var delta = now - start;
            if (delta > timeout)
            {
                http.abort();
                return 'Tmo';
            }
        }
        while(http.readyState != 4);
    }
    catch(erreur)
    {
        return 'Err';
    }
    return(http.status);
}

With the do..while loop, I can set the acceptable time to wait for the http response.
The function is called from an other one in a loop "for" and each loop has a different url as input. Why this is OK with IE5 and not with IE6 .... ?

A similar thing seams more difficult to do using the onReadyStateChange method and this is e new problem. I think setTimeouts or setInterval commands will be useful. Unless you know something for pausing, like sleep or delay...

JFB

joefawcett · October 24th, 2004, 03:27 AM

I don't know why IE6 differs from IE5, I don't have version 5 to test with.
Unfortunately although the ServerXmlHttp class has a waitForResponse method the standard version does not.
On my company intranet I use meadroid.com scriptX component for pausing. It also has some useful functions for printing and doing awkward JavaScript operations such as passing by reference.

--

Joe