Google Site Map Rss Feed For Latest Additions

`feed.rss` and `sitemap.xml`

posted October 2, 2011 by Stephan Brumme

Discovery

In November 2010 I saw space shuttle Discovery in Cape Canaveral. A completely different kind of discovery is widespread among internet sites, especially blogs:

RSS feeds for news readers
Sitemaps for search engines

Both are available now for create.stephan-brumme.com.

News feed - `feed.rss`

My RSS 2.0 feed is generated on-the-fly by a simple PHP script.

Except for <lastBuildDate> and <pubDate>, the header (everything up to <item>) is static.
All <item> tags are filled while scanning the file system. The optional <description> is missing at the moment but might appear over the next days. A small excerpt is shown below:

I had to ran several validation tests with the W3 RSS validator until it passed all tests:

My main problem was that the validator is quite picky about the date format. During the process of getting everything right, I learnt about PHP's constant DATE_RFC2822 (I never heard about it before), I learnt that I should use gmdate instead of date and found at least 2 small bugs in my homegrown Content Management System.

Search Engine Feed - `sitemap.xml`

Search engines like Google are responsible for the vast majority of my web site visitors. Often it takes several days - and sometimes over a month - for their web spiders to discover new additions to my web site. A sitemap.xml speeds up this discovery process by magnitudes. Read more about sitemaps and their XML specification.

The code is almost the same as used for the RSS feed. This time, date("c", $someTimestamp) works best for lastMod. The changefreq is manually set to monthly for all blogs entries and weekly for the front page. Priorities are manually set as well to 0.5 or 0.8. A small excerpt is shown below:

Configuring Apache

Most Apache web servers only sent .PHP files to the PHP compiler. There are two options to generate the feeds with PHP:

mod_rewrite
parse .rss and .xml with PHP

If mod_rewrite is available, you can add these rules (regular expressions) to .htaccess:

RewriteEngine On RewriteRule ^sitemap.xml$ /sitemap.php [last] RewriteRule ^feed.rss$ /feed.php [last]

All accesses to sitemap.xml and feed.rss are redirected to some PHP files which in turn must contain the necessary code to generate the proper feeds.

The mod_rewrite techniques works very well but this time I went for method 2 and added this single line to .htaccess:

AddType x-mapp-php5 .xml .rss

sitemap.xml and feed.rss now actually exist on my server and contain all required PHP code.
Note: Be careful when adding other .rss or .xml files because this might produce undesired results, especially mis-interpretation of the first line's <? and ?>.