Database instead of kml file - google-maps

Question

I wonder, is it possible to connect a db to google maps api to render polygons, points etc?
If a store all kml coordinates connected to polygons, will it be possible to render it fra database or do i need to create a kml file to visualize it?
Is there any example?
Thanks!

Answer 1

A KML file is not required to visualize points, polygons, etc using Google Maps API. However, the KML layer is a useful way to represent complex geospatial features.
A backend database with HTTP access could return a list of map coordinates that your client code can render into appropriate shapes using Google Maps API.
The Google Maps API provides examples to create various shapes.
Example to create simple point marker:
https://developers.google.com/maps/documentation/javascript/examples/marker-simple
Example to create simple polygon:
https://developers.google.com/maps/documentation/javascript/examples/polygon-simple
The client code will need to query the data from the database such as from a servlet with access to the database. Database will most likely be running on a different port or from a different server so javascript won't be able to access it directly.
Your server-side component could query a database and return formatted KML or it could return a JSON result that your client code would render. Depends on whether you want to write more backend server code or JavaScript code on the client.

Answer 2

hmmm... I am using another solution now (data from DB to show on Google earth which is default application for KML file) and hope this help :
( may refer to https://sites.google.com/site/canadadennischen888/home/kml/auto-refresh-3d-tracking )(plus, in my other page, there is sample java code)
Details as :
prepare a RestFul service to generate KML file from DB (KML sample as inside above link)
My other jsp code will generate a KMZ file which has a link to my Restful service. KMZ file has onInterval ( as in the bottom)
Jsp web page allow user to download KMZ file.
When Google Earth open KMZ file, Google Earth will auto refresh to get new data from that Restful service
Everytime refreshing, server will send the latest update KML data with new data to GE.
KMZ sample:
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2" xmlns:gx="http://www.google.com/kml/ext/2.2"
xmlns:kml="http://www.opengis.net/kml/2.2" xmlns:atom="http://www.w3.org/2005/Atom">
<NetworkLink>
<name>Dennis_Chen_Canada#Hotmail.com</name>
<open>1</open>
<Link>
<href>http://localhost:9080/google-earth-project/rest/kml/10001/20002</href>
<refreshMode>onInterval</refreshMode>
</Link>
</NetworkLink>
</kml>
result as :

Answer 3

Thanks for you're answer. I don't know if i get somewhat wiser of this, but at least i know that it is possible.
I have used Shape2Sql to save the coordinates in the database.
But as i understand, i need someway to convert this to geojson before it can render in Google maps? if i understand correct?
As i understand to render geojson is mostly the same as to render kml when it comes to files. But i don't know how to Connect to a database.
I make a list from database:
var adresses = _unitOfWork.GeoAddressRepository.Get(q => q.GeoRouteNorpost.Code == "3007106", includeProperties: "GeoRouteNorpost").ToList();
var points = new List<LatLong>();
foreach (var address in adresses)
{
points.Add(new LatLng() { Lat = "59.948261", Lng = "10.750699" });
points.Add(new LatLng() { Lat = "59.943128", Lng = "10.755814" });
points.Add(new LatLng() { Lat = "59.941245", Lng = "10.746084" });
points.Add(new LatLng() { Lat = "59.943527", Lng = "10.742786" });
points.Add(new LatLng() { Lat = "59.946824", Lng = "10.744435" });
points.Add(new LatLng() { Lat = "59.946813", Lng = "10.744446" });
points.Add(new LatLng() { Lat = "59.947107", Lng = "10.748241" });
points.Add(new LatLng() { Lat = "59.947827", Lng = "10.749525" });
points.Add(new LatLng() { Lat = "59.948248", Lng = "10.750699" });
}
This example show a polygon on a map. But i'm not sure how to get this coordinates out of the database and how to solve it when it is serveral polygons.
As i have written, i have saved the coordinates in the db With shape2Sql. So now i have a Field for geometry. If i look at the spatial result in sql server this looks correct. But how can i display this in Google maps?
I am grateful for all help:)