Google Inc.s Web Accelerator application, launched as a test on Wednesday, uses a combination of local and server-based caching and preloading of Web pages to more quickly serve Web pages to a users browser. Googles servers, in many ways, act as an intermediary between Web sites and a users browser.
But Googles approach has had some unintended consequences. Google officials Friday confirmed that the company was aware of as many as five sites where Web Accelerator was returning users cached pages under other peoples user names.
The Mountain View, Calif.-based company has stopped caching pages from those sites, said Marissa Mayer, Googles director of consumer Web.
Users of some smaller Web forum sites have complained in online postings that they began receiving Web pages which displayed other peoples user names after downloading Web Accelerator. The forum site, Somethingawful.com, was among those warning its users to avoid Web Accelerator because of reports that pages from other users logins were exposed.
"It is an unfortunate problem, but it looks worse than it is," Mayer said. "We are caching those pages on the server side with the user name on them…You see it, but its important to point out that you are not logged in as user and you do not have the session cookies needed to perform operations as [that] user."
Mayer said the problem stemmed from the way some sites have implemented their HTTP cache-control headers, which provide information such as language preferences to a browser. Google uses those headers to determine whether a page is meant for an individual user, in which case it would not live on its servers, Mayer said.
Google plans to notify the Webmasters of the affected sites about the need to fix their cache-control headers as well as work on a solution within Web Accelerator, Mayer said.
Web Accelerator already prevented secure sites using the HTTPS protocol, such as online banking and e-mail sites, from being cached.
Web Accelerators problems appear to extend beyond forum sites, though. Web-based software developer 37Signals LLC began blocking the program after discovering that it was initiating links which performed critical functions, such as account deletions, on 37Signals Web applications.
A few users complained about deleted accounts on 37Signalss Basecamp and Backpack applications, and the company traced the problem to Web Accelerator, said 37Signals President Jason Fried. To make matters worse, the problem occurred the same week that the Chicago-based company launched Backpack, a personal-information management application.
"It was serious enough to frighten us, since we had just released a product and it coincided with Googles release," said Fried, who first wrote about the issue in his Weblog. "We became aware of the Web Accelerator issue, and within 30 minutes of figuring it out we instituted a block."
As for Web Accelerators impact on Web applications, Mayer initially said that most of the reports she had seen appeared to be unsubstantiated. When informed about 37Signals problems, she said that it is possible that some sites are not complying with a Web standard used by Web Accelerator.
Web Accelerator ignores links where a question mark appears before the URL string in the HTML code. A question mark is usually included in a string to indicate personally identifiable information such as a user ID and would typically be used in a link that performs a function like a deletion, Mayer said.
"The product is in beta," Mayer said. "It could be that our assumption around the question mark and the way sites comply with the standard is incorrect. If that is the case, then well have to redesign the prefetch algorithm."
Fried acknowledged that the applications do not conform to all standards. For example, functions such as a deletion technically should be handled with buttons rather than links, he said.
Google needs to recognize, however, that many sites use methods that vary from standards, he said.
"To me, the real test here is not so much that Google may have made mistake but how they respond to it," Fried said. "Are they going to call it a mistake or blame everyone else to [make them] build products the way they should be built in a perfect world?"