How to Generate a kml through a handler while getting the points from sqlserver into a asp.net

Question

I am new in asp.net and I am not understanding how to generate a kml file using an Generic Handler file. I am able to create an handler file and confused where and how to connect database and get the latitude and longitude and define it in kml and should be able to generate the kml.

I had a database table like pmis_gpspoints where in I have columns as p_latitude,p_longitude,p_cd.

I would be passing the p_cd value to the generic handler file for the required kml file.

Anybody please help me out with any code snippets or ideas or references so that I could work out ?

Answer 1

Try to place all the code inside the Process Request.

Initially we retrieve the p_cd from Query String.

And then will connect to database and get the required gps points.

And then we would be writing kml using XMLTextWriter.

public void ProcessRequest(HttpContext context)
        {

            //context.Response.ContentType = "text/plain";
            context.Response.ContentType = "application/vnd.google-earth.kml+xml";

            string id = context.Request.QueryString["ID"].ToString();

            FileName = "KML File";

            context.Response.AddHeader("Content-Disposition", "attachment; filename=" + FileName + ".kml");
            Query = "select * from pmis_hh_gpspoints where p_cd='" + id + "' order by p_gps_cd ";
            SqlConnection conn = new SqlConnection(conStr);
            conn.Open();
            SqlDataAdapter da = new SqlDataAdapter(Query, conn);
            DataSet ds = new DataSet();
            da.Fill(ds);
            XmlTextWriter kml = new XmlTextWriter(context.Response.OutputStream, System.Text.Encoding.UTF8);
            kml.Formatting = Formatting.Indented;
            kml.Indentation = 3;
            kml.WriteStartDocument();
            kml.WriteStartElement("kml", "http://www.opengis.net/kml/2.2");  /*1*/
            kml.WriteStartElement("Document");  /*2*/
            kml.WriteStartElement("Style");  /*3*/
            kml.WriteAttributeString("id", "bsr");
            kml.WriteStartElement("LineStyle");  /*4*/
            kml.WriteElementString("width", "4");
            kml.WriteElementString("color", "ff0000ff");
            kml.WriteEndElement();  /*-4-*/
            kml.WriteStartElement("PolyStyle");  /*5*/
            kml.WriteElementString("color", "51400FF");
            kml.WriteEndElement();  /*-5-*/
            kml.WriteEndElement();  /*-3-*/
            kml.WriteStartElement("Placemark");  /*6*/
            kml.WriteElementString("styleUrl", "#bsr");

            kml.WriteStartElement("Polygon");  /*7*/
            kml.WriteElementString("extrude", "1");
            kml.WriteElementString("tessellate", "1");
            kml.WriteElementString("altitudeMode", "ALTITUDE_CLAMP_TO_GROUND");
            kml.WriteStartElement("outerBoundaryIs");  /*8*/
            kml.WriteStartElement("LinearRing");  /*9*/
            kml.WriteStartElement("coordinates");  /*10*/
            for (int i = 0; i <= ds.Tables[0].Rows.Count - 1; i++)
            {
                kml.WriteValue("" + ds.Tables[0].Rows[i]["p_longitude"].ToString() + "," + ds.Tables[0].Rows[i]["p_latitude"].ToString() + ",0 ");
            }
            kml.WriteValue("" + ds.Tables[0].Rows[0]["p_longitude"].ToString() + "," + ds.Tables[0].Rows[0]["p_latitude"].ToString() + ",0 ");
            kml.WriteEndElement();  /*-10-*/
            kml.WriteEndElement();  /*-9-*/
            kml.WriteEndElement();  /*-8-*/
            kml.WriteEndElement();  /*-7-*/

            kml.WriteEndElement();  /*-6-*/
            kml.WriteEndElement();  /*-2-*/
            kml.WriteEndElement();  /*-1-*/
            kml.WriteEndDocument();
            kml.Close();
            conn.Close();
        }

Refer the handler file with the right parameter, where ever you are trying to show whether it is in grid or any other place...the kml files gets downloaded with the filename mentioned in the code.