Question

I’m building out an API and have a question about how to track/know which domains use the call after the KML gets picked up by Google’s servers for rendering.

So, for example, my domain that is serving up the KML file is called kml.example.com from a PHP API. Someone on the domain http://www.metromapper.org builds a page that creates a Google map and then calls my file using Ajax to overlay my data on their map. Google grabs that KML file, then serves it back to the user.

Here is that example in action: http://www.metromapper.org/example/apitest.htm

(Click the center map marker to see a popup of all the PHP server variables available to the kml.example.com script.)

Since Google is grabbing it, I can’t use the PHP variables REMOTE_HOST or REMOTE_ADDR to get the metromapper.org site info. They only tell me Google’s IPs.

So is there some other way to get this data? Does Google happen to return it in the header somewhere? Any ideas on how to track or pass the originating remote host name around so I can get it when the call is made? Thanks, I realize this might not be solvable.

FYI, I posted this question too, but it was before I knew it was Google’s IP in the REMOTE_HOST.

Answer 1

You could construct your KML URL like so:

var layer = new KMLLayer("http://yoursite.com?caller=" + window.location.host);

Your server will then get passed the hostname of the current page as a CGI parameter, which it can record.

Note that this has implications for caching—every site which embeds your KML file will append a different caller parameter, so Google will not be able to share cached copies of the KML between multiple sites. This may impact performance.

A better strategy may be to make an AJAX call to your domain each time someone loads the KML file, e.g.:

var layer = new KmlLayer("nice_cachable_url");
LogQuery(layer, window.location.host);

LogQuery would use AJAX or a similar technique to send the KML Layer ID and current host name to your server. Your server can then track this.