diff --git a/engine/Sitemap.php b/engine/Sitemap.php
new file mode 100644
index 0000000..a0ccee1
--- /dev/null
+++ b/engine/Sitemap.php
@@ -0,0 +1,105 @@
+<?php
+
+class Sitemap
+{
+	private static $cache_path = "";
+	private static $xml_file_path = "";
+	private static $robots_file_path = "";
+
+	// you can override these in config.php; e.g.:
+	// Sitemap::$sitemap_name = "different_sitemap_name.xml";
+	public static $sitemap_name = "sitemap.xml";
+	public static $robot_name = "robots.txt";
+	public static $index_changefreq = "daily";
+	public static $index_priority = "1.0";
+	public static $page_changefreq = "monthly";
+	public static $page_priority = "0.8";
+	public static $post_changefreq = "monthly";
+	public static $post_priority = "0.8";
+
+	public static function should_write_sitemap($dp)
+	{
+		return (!file_exists($dp . "/" . self::$sitemap_name));
+	}
+
+	public static function write_sitemap($dp, $cp)
+	{
+		self::$cache_path = $cp;
+
+		self::$xml_file_path = $dp . "/" . self::$sitemap_name;
+		self::$robots_file_path = $dp . "/" . self::$robot_name;
+
+		error_log("writing sitemap (" . self::$xml_file_path . ")");
+		self::write_header();
+		self::entry("", time(), self::$index_changefreq, self::$index_priority);	// entry for the index page
+		self::process_cache();
+		self::write_closing();
+
+		self::generate_robot_file();
+	}
+
+	private static function write_header()
+	{
+		$t = '<?xml version="1.0" encoding="UTF-8"?>' . "\n";
+		file_put_contents(self::$xml_file_path, $t);
+
+		$t = '<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">' . "\n";
+		file_put_contents(self::$xml_file_path, $t, FILE_APPEND);
+	}
+
+	private static function write_closing()
+	{
+		$t = '</urlset>' . "\n";
+		file_put_contents(self::$xml_file_path, $t, FILE_APPEND);
+	}
+
+	private static function process_cache()
+	{
+		if (is_dir(self::$cache_path)) {
+			if ($dh = opendir(self::$cache_path)) {
+				while ( ($file = readdir($dh) ) !== false) {
+					if (substr($file, 0, 4) != "dir-") continue;
+					$fullpath = self::$cache_path . '/' . $file;
+					$fileinfo = unserialize(file_get_contents($fullpath));
+					foreach ($fileinfo as $key => $value) {
+						$filename = pathinfo($key, PATHINFO_FILENAME);
+						$parent = array_pop(split("/", pathinfo($key, PATHINFO_DIRNAME)));
+						$ts = array_shift(split("-", $value));
+						if ($parent == "pages")
+						{
+							self::entry($filename, $ts, self::$page_changefreq, self::$page_priority);
+						}
+						elseif (pathinfo($key, PATHINFO_EXTENSION) == substr(UPDATER::$post_extension, 1))
+						{
+							$location = substr($filename, 0, 4) . "/" . substr($filename, 4, 2) . "/" . substr($filename, 6, 2) . "/";
+							$location .= substr($filename, 12);
+							self::entry($location, $ts, self::$post_changefreq, self::$post_priority);
+						}
+					}
+				}
+			}
+		}
+	}
+
+	private static function entry($loc, $lastmod_timestamp, $changefreq, $priority)
+	{
+		$entry  = "";
+		$entry .= "<url>" . "\n";
+		$entry .= "<loc>" . POST::$blog_url . $loc . "</loc>" . "\n";
+		$entry .= "<lastmod>" . date("Y-m-d", $lastmod_timestamp) . "</lastmod>" . "\n";
+		$entry .= "<changefreq>" . $changefreq . "</changefreq>" . "\n";
+		$entry .= "<priority>" . $priority . "</priority>" . "\n";
+		$entry .= "</url>" . "\n\n";
+
+		file_put_contents(self::$xml_file_path, $entry, FILE_APPEND);
+	}
+
+	private static function generate_robot_file()
+	{
+		error_log("writing robots.txt");
+		file_put_contents(self::$robots_file_path, "User-agent: *" . "\n");
+		file_put_contents(self::$robots_file_path, "Disallow:" . "\n", FILE_APPEND);
+		file_put_contents(self::$robots_file_path, "" . "\n", FILE_APPEND);
+		file_put_contents(self::$robots_file_path, "SITEMAP: " . Post::$blog_url . self::$sitemap_name . "\n", FILE_APPEND);
+	}
+}
diff --git a/engine/Updater.php b/engine/Updater.php
index 3c51c52..d1c1bad 100755
--- a/engine/Updater.php
+++ b/engine/Updater.php
@@ -2,6 +2,7 @@
 
 require_once(dirname(__FILE__) . '/Post.php');
 require_once(dirname(__FILE__) . '/Hook.php');
+require_once(dirname(__FILE__) . '/Sitemap.php');
 
 class Updater
 {
@@ -675,6 +676,10 @@ private static function _update($restart_if_resequenced = true)
                 );
             }
         }
+
+		if ((self::$changes_were_written) || (Sitemap::should_write_sitemap(self::$dest_path))) {
+			Sitemap::write_sitemap(self::$dest_path, self::$cache_path);
+		}
     }
 }