[OpenLayers-Users] Re: WMSGetFeatureInfo - slow response in IE8 and 9

Mon Mar 12 14:29:46 EDT 2012

Andreas,

I'm sorry, but I don't really understand how to carry out what you're
describing.  I originally just specified <!DOCTYPE html> for the page and
the same thing occurs.  I searched the mapserver code for GetFeatureInfo and
DOCTYPE and I couldn't easily see in the code where this might pertain to
getfeatureinfo, as in doesn't appear to be referring to a dtd when carrying
out the request.  The only references to DOCTYPE are in formatting error
exceptions when the WMS request string isn't formatted properly.

I tried a suggestion from W3 about specifying a local area for the dtd. 
Unfortunately, I'm unable to install Fiddler on this one machine I'm working
and will have to check later. 

However, I also decided to debug within IE8 and there's a lengthy delay in
the OpenLayers code, XMLHttpRequest.js.  It seems to loop at least 4 times
in 

        this._object.onreadystatechange    = function() {

 and on the 4th 

the routine goes through:

            if (oRequest.readyState == cXMLHttpRequest.DONE) {
                // Free up queue
                delete oRequest._data;

                fCleanTransport(oRequest);

               // BUGFIX: IE - memory leak in interrupted
                if (bIE && bAsync)
                    window.detachEvent("onunload", fOnUnload);

            // BUGFIX: Some browsers (Internet Explorer, Gecko) fire OPEN
readystate twice
            if (nState != oRequest.readyState)
                fReadyStateChange(oRequest);

When it hits fReadyStateChange(oRequest), this is where a delay occurs
before continuing onto the next statement.

After that delay, it moves onto:

            nState    = oRequest.readyState;
        }

And returns the value from MapServer.

In Firefox and with Firebug,

         this._object.onreadystatechange    = function() { 

is not even entered.

I'll still look at this from the MapServer point of view and perhaps check
about bypassing the dtd somehow.  But, there looks to be a possible issue
with how this is being handled within OL.

Dave M

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