Google maps API - Displaying routes/polylines, kmlLayer alternative

Question

I am developing a web application where i have database backend with geo located objects, and each one has it's geo data stored in a kml file. When displaying object on a google map, via google maps js api v3, i have a following scenario: first i do a json call, and it returns array of objects. Each json object is has it's geo location, either a gmap marker or route/polyline. Every object has properties: id, name, description, kml_url… etc. Kml_url is url of the kml file, that is used to plot an object on a map, through the "new google.maps.KmlLayer(…)" call. Every created kmlLayer is bound to its json object, so it can be manipulated (show/hide, for example) through that object by js. Then, every kmlLayer get it's mouse click event listener with "google.maps.event.addListener(…)", and the response is dynamically generated from the kml's json object attributes (it grabs the id attribute and through another json call it displays object's details).

The problem is, when more than let's say 10 kml layers are created, i hit the "NetworkError: 414 Request-URI Too Large". I found that i can get rid of the error by using kml network links, but AFAIK, in this case i loose the ability to manipulate every object through it's json object (with bounded kmlLayer that is created).

What would be the alternative for this sort of application, maybe not using kml-s at all ? If i go for using overlays, and drawing all the routes and markers myself, i am afraid i will end up with scalability issues, because drawing 15 routes, every with 50 polyline nodes, and another 15 markers, would take considerable amount of time on a client.

Thank you, Emil

Answer 1

I've had great success with GeoXML3 for handling large numbers of KML files, each with many elements (including placemarks, polylines, and polygons). I recommend you get the polys branch, which as of this post has the most features. There's a current big effort going on in the KMZ branch that will handle KMZ (zipped) files, but this is not quite ready for production, in my opinion.

For my own edificaiton, I created a Github project which uses the Google API v3, Geoxml3, and displays a sidebar and layer controls. It also uses some more advanced features like the afterParse hook and an addition I use that triggers a parsed event on the Geoxml3 object.