[pubsubhubbub] PubSubHubbub for Sitemaps

[Kate Volkova]

Hello PubSubHubbub developers and users!

We would like to add PubSubHubbub support for
Sitemaps<http://www.sitemaps.org/> to
make it even more similar to Atom and RSS feeds.

A Sitemap <http://www.sitemaps.org/> is an XML file that lists several
entries each in its own <url> tag. Each entry has a URL associated with it
(under <loc> tag), which can be used as an entry id. Each entry may also
contain additional metadata about the URL (when it was last updated, how
often it usually changes, etc.). Here is an example of a Sitemap from
http://www.sitemaps.org/:

<?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>monthly</changefreq>

      <priority>0.8</priority>

   </url>

   <url>

      
<loc>http://www.example.com/catalog?item=12&amp;desc=vacation_hawaii<http://www.example.com/catalog?item=12&desc=vacation_hawaii>
</loc>

      <changefreq>weekly</changefreq>

   </url>

</urlset>


The same Sitemap with PubSubHubbub support would look like this:

<?xml version="1.0" encoding="UTF-8"?>

<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"* **xmlns:atom="
http://www.w3.org/2005/Atom*";>

   *<atom:link rel="hub" href="**http://myhub.example.com/endpoint"/>*

   <url>

      <loc>http://www.example.com/</loc>

      <lastmod>2005-01-01</lastmod>

      <changefreq>monthly</changefreq>

      <priority>0.8</priority>

   </url>

   <url>

      
<loc>http://www.example.com/catalog?item=12&amp;desc=vacation_hawaii<http://www.example.com/catalog?item=12&desc=vacation_hawaii>
</loc>

      <changefreq>weekly</changefreq>

   </url>

</urlset>


Diffs between previous and current version of the feed will be computed the
same way as it’s done for Atom and RSS feeds:

 - For each entry sha1(entry) is computed and compared with the old hash
value for the same entry_id.
 - If the hash value has changed or there is no old hash value for this
entry_id (an entry is new), the entry is added to the list of items to
publish for this topic (feed_url)

Any comments on this?

Thanks!

--
Kate Volkova,
Software Engineer, Google.