[ka-Map-users] Speeding up tile display/download

Ionut Muntean ionut at muntean.ro
Sat Feb 17 14:00:46 EST 2007


Don't know if this is already known by you, but it is worth a try to 
share this.

I've always wondered why google maps displays the tiles so fast. 
mt0..mt3.google.com resolves to the same server. So what's the clue? 
Fortunately, i've bumped on some web page where it says that IE and 
Firefox have only 4 sockets for downloading the web page content.

So, what if altering kaMap.setTile() to use, sequentially, 4 server 
names to build img.src?

The improvement was dramatically! The tiles are now loading 4 to 5 times 

tileURL is now an array that holds 4 server names that are basically 
only cnames in the dns server to the same server.

The setTile() function was modified to sequential build the img.src like 
this (this is only the last part of the function):

    var idx = this._map.kaMap.tileIDX;
     if (this._map.kaMap.tileURL[idx].indexOf('?') != -1) {
         if (this._map.kaMap.tileURL[idx].slice(-1) != '&') {
             q = '&';
         } else {
             q = '';
     } else {
         var src = this._map.kaMap.tileURL[idx] +
         q + 'map=' + this._map.name +
         '&t=' + t +
         '&l=' + l +
         szScale + szForce + szGroup + szImageformat + szTimestamp + 
     if (img.src != src) {
         img.style.visibility = 'hidden';
         img.src = src;
    if (idx == this._map.kaMap.tileURL.length) {
      this._map.kaMap.tileIDX = 0;
    } else {
      this._map.kaMap.tileIDX = idx;

Of course this method presumes that you have access to the DNS servers 
of the company or whoever is hosting your pages.

Hope this is usefull info for someone.

/ IM

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