Google has blocked Facebook from “scraping” some types of data from its servers, setting off a telling skirmish in the broader war between the two internet powers that many observers believe will shape the next phase of the web.
The new bar ends Facebook’s automated access to lists of contacts kept by Google’s Gmail users, considered valuable data as Facebook seeks to expand the “social graph” of connections it maintains for its own 550m users.
Until now, Facebook has been able to offer anyone setting up a new account the option to import their contact lists automatically from web e-mail services like Gmail, Microsoft’s Hotmail and Yahoo Mail.
Those lists have provided a quick way to build a network of social connections on Facebook.
On Friday, Google said it had changed its rules to block Facebook’s computers from tapping into its own systems to carry out this function.
The move had been prompted by Facebook’s refusal to offer a reciprocal service, it added.
The contact information to which Google seeks access was Facebook’s “core asset”, said Ray Valdes, an analyst at Gartner.
For a long time, Facebook’s resistance to letting its users download their personal information from the service allowed rivals such as Google to paint it as a restrictive, or “closed”, service, in contrast to their own, more open approach.
Last month Facebook changed course and said users could extract all their personal data from the service, although it still does not offer the sort of easy, automated access Google is demanding, and does not let users take the all-important contact information for their friends that would help a service like Google build a rival social network.
Google accused Facebook of leaving “users in a data dead end”. To avoid being seen itself as becoming more restrictive, the search company claimed that its fight for reciprocity “will be an important step towards creating a world of true data liberation”.
The fight over contact information pointed to a key battle shaping the web’s future, Mr Valdes said. “There are different centres of power and agendas of self-interest on the web, but the fundamental power conflict is emerging between Google and Facebook.”
Skirmishes over automated access to data have become more familiar as rivals seek to build walls around the information they consider most valuable. Access is made through connections known as application programming interfaces, or APIs.