Un sitemap és un llistat de URLs que té un format definit per la Sitemap.org i que s'envia als motors de cerca per tal que les indexin. El seu format és el següent:

<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
<url>
  <loc>http://www.example.com/</loc>
  <lastmod>2005-01-01</lastmod>
  <changefreq>daily</changefreq>
</url>
<url>
  <loc>http://www.example.com/</loc>
  <lastmod>YYYY-MM-DD</lastmod>
  <changefreq>weekly</changefreq>
</url>
</urlset>

He fet un petit programa en C# que genera aquest XML, he vist exemples on es fan servir objectes XMLDocument i es van afegint nodes fills etc... Donat que no és gaire complicat jo ho fet en cadenes de text directament. Apart d'això només s'ha de posar el Content-Type que toca: text/xml El codi a continuació

public class Sitemap : IHttpHandler
{
	private clsConfig Conf = new clsConfig();
	private string ConnStr;
	private HttpResponse Resp;
	private HttpRequest Req;
	public void ProcessRequest(HttpContext context)
	{
	    StringBuilder SB = new StringBuilder();
	    Conf.Initialize();
	    ConnStr = Conf.GetVal("CadConn");
	    Resp = context.Response;
	    Req = context.Request;
	    clsPosts Posts = new clsPosts(ConnStr);
	    DataTable TBL;
	    string SQL = "";
	    Dictionary<string, string> Params = new Dictionary<string, string>();
	    Resp.ContentType = "text/xml";
	    
	    SB.Append("<?xml version=\"1.0\" encoding=\"UTF-8\"?>" + Environment.NewLine);
	    SB.Append("<urlset xmlns=\"http://www.sitemaps.org/schemas/sitemap/0.9\">" + Environment.NewLine);
	    SB.Append("<url>" + Environment.NewLine);
	    SB.Append("<loc>http://blog.canalda.net/</loc>" + Environment.NewLine);
	    SB.AppendFormat("<lastmod>{0}</lastmod>" + Environment.NewLine, DateTime.Now.ToString("yyyy-MM-dd"));
	    SB.Append("<changefreq>daily</changefreq>" + Environment.NewLine);
	    SB.Append("</url>" + Environment.NewLine);

	    SQL = "SELECT IdPost, DataMod FROM Posts WHERE Actiu=1;";
	    TBL = Posts.Exec(SQL);

	    foreach (DataRow DR in TBL.Rows)
	    {
		SB.Append("<url>" + Environment.NewLine);
		SB.AppendFormat("<loc>http://blog.canalda.net/Post.aspx?IdPost={0}</loc>{1}", 
                  DR["IdPost"].ToString() , Environment.NewLine);
		SB.AppendFormat("<lastmod>{0}</lastmod>{1}",
                  DR.Field<DateTime>("DataMod").ToString("yyyy-MM-dd"),
		  Environment.NewLine);
		SB.Append("<changefreq>monthly</changefreq>" + Environment.NewLine);
		SB.Append("</url>" + Environment.NewLine);                
	    }

	    SB.Append("</urlset>" + Environment.NewLine);
	    Resp.Write(SB.ToString());
	}

	public bool IsReusable
	{
	    get
	    {
		return false;
	    }
	}
}