Yes, great, this is something I have been also thinking about, but
didn't have enough knowledge what time-profiling techniques/
technologies are available on the server side.
Here are some comments/notes.
- response headers
yes, I think this is the way how to get the server side timings to the
client.
- 'waiting' phase
Precisely, this phase would be divided into more sections describing
server side timings info. I don't know what are the options here and
it could also depends on the server side capabilities.
- HTTP Archive Format
I believe we can also extend the HAR format to cover also the server
side timing info. The question is whether we can define solid
structure for gathered timings shared across various servers.
http://groups.google.com/group/http-archive-specification/web/har-1-2-spec?hl=en
- NetExport
This is an extension to Firebug that allows exporting the Net panel
data
http://www.softwareishard.com/blog/netexport/
As soon as I have the server-timings in a response headers, I can
extend also the waterfall diagram to display it. I think the code
shouldn't be directly part of Firebug, but provided through an
extension.
- HAR Viewer
Since the purpose of the HAR format is to export HTTP tracing data
from various tools in the same format, there is also an online viewer
that allows to quicly preview & validate existing logs.
http://www.softwareishard.com/blog/netexport/
In case we have a solid extension to the HAR spec, the viewer could be
adapted too.
Honza