W3C home > Mailing lists > Public > public-web-perf@w3.org > October 2010

Re: [Open Issue] Privacy concern with Navigation Timing

From: Sigbjørn Vik <sigbjorn@opera.com>
Date: Fri, 22 Oct 2010 11:40:30 +0200
To: public-web-perf@w3.org
Message-ID: <op.vky05sd841y844@id-c0735.oslo.opera.com>
On Thu, 21 Oct 2010 19:00:56 +0200, Zhiheng Wang <zhihengw@google.com>  
wrote:

> On Thu, Oct 21, 2010 at 7:46 AM, Sigbjørn Vik <sigbjorn@opera.com> wrote:
>
>> Navigation types - these seem a bit underspecified. E.g. automatic types
>> are missing. What about a JS timeout that redirects a user? A window  
>> popup?
>> Meta refresh to reload or move elsewhere? I am not sure if these and  
>> friends
>> should go into type_navigate or type_reserved (or possibly even  
>> type_reload
>> in the case of a meta refresh to self). What does "the reload operation"
>> refer to (we used to have about 5 different reload operations in Opera,  
>> and
>> still have two exposed in the UI)? Would a better name for  
>> type_back_forward
>> be type_history_navigation? Note that back and forward aren't  
>> necessarily
>> well defined either, instant back, conditional get, and full get might  
>> give
>> three different results. I would consider it none of the site's  
>> business to
>> know how I got there, if the second time I visited it I did it via the  
>> same
>> link as the first time, via the forwards button, or in a new tab.  
>> Sometimes
>> this can be determined through a change in the HTTP headers sent, but  
>> apart
>> from that, this might be information users would like to keep private.  
>> Maybe
>> the types should be defined in terms of which HTTP headers the browser  
>> sent
>> instead? If-modified-since = conditional,  
>> cache-control:no-cache/maxage=0 =
>> reload, neither = fresh, none (e.g. instant back or reload from cache)  
>> = the
>> same as last time - that way we aren't revealing anything to the server
>> which the server doesn't already know, and the types might be more  
>> useful
>> for a site developer. A back navigation could be either one of the  
>> above,
>> depending on circumstances, and that doesn't seem very telling for the
>> developer.
>>
>
>     Navigation type provides some background information on data  
> analysis.
> Say, a back/forward page usually loads much faster than a normal  
> navigation.

But isn't the reason for history navigation being faster the way the  
browser loads the page, rather than the way the user requested it? Back to  
a page which is no longer in cache (for whatever reasons) is equivalent to  
a fresh load for purposes of data analysis. Or are you referring to data  
analysis on user habits? And for purposes of data analysis (of load  
times), a fresh load and a conditional get are very different, but will  
not separated based on the suggested definitions of user interaction.

> Fastback is a particular interesting case, where we propose that the
> existing timing information should not be changed since there is no
> navigation.

What about a fresh load entirely from cache? E.g. in offline mode, or  
using a debugging option such as "reload from cache"? The load is fresh,  
the documents may have been changed locally since they were downloaded,  
and the browser might have been restarted, so any previous timings might  
be wrong, and might not be cached either.

And completely unrelated, knowing the navigation type for inlines, e.g.  
images, whether it is fresh, conditional, or plain cache, can be a very  
useful debugging tool. Should this be made available also on inlines? Note  
the potential privacy implications for this.

-- 
Sigbjørn Vik
Quality Assurance
Opera Software
Received on Friday, 22 October 2010 09:40:49 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Tuesday, 21 December 2010 18:13:55 GMT