For some time now I have occasionally advised people involved in repository administration that they should consider registering the Base URL of their OAI-PMH interface (if they have one) with Google as a proxy for a Sitemap. Until recently, Google has supported the use of OAI-PMH Base URLs in its Webmaster Tools which site owners can use to create and register sitemaps in order to give hints about the structure of the website to Google's web-crawler.
A while ago, I noticed that there was no longer any reference to this particular support in any of the documentation and began to suspect that this was being deprecated. Today, Google announced via their official blog that:
...we've found that the information we gain from our support of OAI-PMH is disproportional to the amount of resources required to support it. Fewer than 200 sites are using OAI-PMH for Google Sitemaps at the moment.
In order to move forward with even better coverage of your websites, we have decided to support only the standard XML Sitemap format by May 2008. We are in the process of notifying sites using OAI-PMH to alert them of the change.
Fewer than 200 sites.....
There are a few ways of looking at this. Perhaps 'open access' repositories are less concerned with Google rankings than the typical website owner. Perhaps the penetration of OAI-PMH in the world is still below any level that Google could find particularly interesting - certainly they never went to great lengths to advertise this support while it lasted. Clearly, Google have come to the end of a 'trial period' for their support for this protocol in their main indexing service.
Can we conclude anything from this? Probably not - surely OAI-PMH can thrive without Google Sitemap support? It certainly plays a fairly significant part in my professional life at present! Or should we view this as a symptom of decline....?
The official Google announcement is here.