Version string in manifest.json file

[Maha]

According to the documentation the version specified in the
manifest.json file is a string and could take any value. ie it need
not follow the pattern like v1, v2, v3 etc. If there is any change in
this version string gears will download the modified resource (url).
Also we need to ensure that the string is not repeated. Correct me if
my understanding is wrong.

[AndreasRL]

That is correct. Note that Gears will download all files in the
manifest when the version string is modified.

[Maha]

I have clarification: is there an option to download all the files for
the first time and subsequently download only modified files. I could
see below post which says Gears downloads only modified content:

http://groups.google.com/group/gears-users/browse_thread/thread/51ff905857d0d666/7dd78a2614202613?lnk=gst&q=manifest#7dd78a2614202613

[Ben Lisbakken]

Hey Maha --

When a client goes to your site for the first time, they download all files in the manifest file.  Then, the next time they visit, if the manifest has changed then the client will download only the modified files.  Does this clarify how it works?

-Ben

[Maha]

Thanks Ben and AndreasRL, however I could see a contradiction in your
comments. I tried to change the version number and found that all the
files are download irrespective of whether they are modified or not.
Am i missing something here.

On Aug 5, 9:48 pm, "Ben Lisbakken" <lisba...@google.com> wrote:
> Hey Maha --
>
> When a client goes to your site for the first time, they download all files
> in the manifest file. Then, the next time they visit, if the manifest has
> changed then the client will download only the modified files. Does this
> clarify how it works?
>
> -Ben
>

> On Tue, Aug 5, 2008 at 3:37 AM, Maha <maha.26061...@gmail.com> wrote:
>
> > I have clarification: is there an option to download all the files for
> > the first time and subsequently download only modified files. I could
> > see below post which says Gears downloads only modified content:
>

> >http://groups.google.com/group/gears-users/browse_thread/thread/51ff9...

[AndreasRL]

Ben,

You're claiming that Gears works just like I would like it to work,
but
my application does not behave like you say it should.

Are we misunderstanding each other here? If the manifest-version has
changed, Gears will download ALL files, no matter they've changed or
not. Right?

[AndreasRL]

Hello again,

I can gladly report that I was wrong, and of course Ben is right. I
can confirm that only files that have changed will be downloaded (if
the server responds with the correct last-modification date).

When the manifest-version is changed, Gears checks the last-mod date
on all the files and downloads only files that have changed. So far my
files have been pretty small so I thought Gears was actually
downloading the file when it was really just checking it's last-mod
date. Now, with larger files, I realize that Gears is not downloading
them but checking them.

[Ben Lisbakken]

Andreas --

Yes, that is correct.  It does depend on the server responding with a correct last-modification date.  Did you change anything to make it work as it is supposed to?  If so, maybe you could share that with the group.

Thanks,
Ben

[AndreasRL]

Ben,

I didn't change anything. It was actually working like it is supposed
to all the time. The "problem" was that my manifest only consisted of
about 70 files, all of them fairly small in filesize. As our corporate
intranet is pretty fast, the conditional GET's on these files took
almost as "long" time as actually downloading the files. To me it
appeared as if Gears was downloading these files but it was just
checking their last-modification date.

To test this I'm now using a manifest with 411 files, with a total
filesize of 426 MB. With this large amount of data it is easy to see
that Gears does not download the full files when the manifest version
is changed:

411 files, 426 MB initial download = 2 min
Same files, manifest version change = 15 seconds

I'm considering doing some research on how Apache handles these kind
of conditional GET requests. Perhaps there are some tweaking
possibilities to speed up this process a bit, if you know of any or
where to start I'd be happy to know :)

On Aug 8, 6:48 pm, "Ben Lisbakken" <lisba...@google.com> wrote:
> Andreas --
>
> Yes, that is correct.  It does depend on the server responding with a
> correct last-modification date.  Did you change anything to make it work as
> it is supposed to?  If so, maybe you could share that with the group.
>
> Thanks,
> Ben
>