RE: [ResourceTiming] Missing size property

Hi Klaus!

We had discussed potentially adding a size attribute to the Resource Timing object, but were concerned that it could leak private information about the user.


*         If the size attribute was defined as the number of bytes that were downloaded over the network for that resource, a size of 0 would indicate that the resource was already in the user's cache.  This leaks private information.



*         If the size attribute was instead defined just the size of the resource, we thought exposing the size wouldn't be as useful (it wouldn't give you the knowledge of the total number of bytes transferred over the network to display the page).

- Nic

From: public-web-perf-request@w3.org [mailto:public-web-perf-request@w3.org] On Behalf Of Klaus Pesendorfer (Fabalabs)
Sent: Thursday, June 30, 2011 7:47 AM
To: public-web-perf@w3.org
Subject: [ResourceTiming] Missing size property

Hello!

The "Resource Timing" standard (working draft) is very interesting and I hope it will be soon implemented by many web browsers,
but I'm missing an essential data property for each loaded resource: the size of the resource (in bytes) that is loaded!
The performance timing values would be much more meaningful if you know how big the file was that was loaded so you can interpret if the network is the bottleneck or if the file is really too big (e.g.: compress the image to reduce the size).
(Or is there another possibility to get the file size of those measured resources from JavaScript?)

So it would help many people to add a size attribute additional to the existing resource description attributes of type and url:

readonly attribute unsigned short type<http://w3c-test.org/webperf/specs/ResourceTiming/#type>;

readonly attribute DOMString url<http://w3c-test.org/webperf/specs/ResourceTiming/#url>;

+ readonly attribute unsigned long long size;      // file size in Bytes

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Do you know when the first web browser will implement the resource timing interface? (IE10?, Chrome, Firefox 6?, ...)

Kind regards,
Klaus Pesendorfer.