[maemo-developers] Non-user/ packages and updating

[From: Eino-Ville Talvala]

  On 9/27/2010 8:59 PM, Alistair Buxton wrote:
> On 28 September 2010 00:41, Eino-Ville Talvala<talvala at stanford.edu>  wrote:
>>   Hi,
>>
>> I have a question about how extras packages not in the user/* hierarchy interact with the application manager and updating.
>>
>> As part of the FCam API, we have a package, fcam-drivers, which replaces the built-in camera driver modules with slightly modified ones.  Previously, I've been listing it under user/Multimedia, but it's been made clear that that's against packaging policies, since it's not a end-user application.
>>
>> So, when we made a few minor bug fixes to it recently, I changed the section to 'utils', since there didn't seem to be any guidance on non-user/* section names, and that's what some other kernel-modifying packages use.  I uploaded fcam-drivers 1.0.7 to extras-devel a few hours ago.
>>
>> However, I haven't received any notification in the N900 interface to update to the new package - I only have extras-devel enabled, and 'apt-cache pkginfo fcam-drivers' lists the new version 1.0.7.  'apt-get upgrade' does tell me it will upgrade fcam-drivers, but Application Manager doesn't know about any updates.
>>
>> Is this the expected behavior, or has the section change caused a problem?  I know that non-user/* packages won't show up as installable, but if they don't appear as updateable either, how do we distribute bugfixes to fcam-drivers, for example, if the only way end users will get the update is through an apt-get upgrade?
> (correcting accidental off-list reply)
>
> H-A-M will never notify you of an update for a package that is outside
> of user/* so you must upload a new version of fcam with an explicit
> dependency on the latest version of fcam-drivers. The user would then
> see an update for fcam, and installing that would force the updated
> fcam-driver to be installed. You must do this every time you want to
> update fcam-drivers, even if you didn't modify the fcam package at
> all. It gets worse if you have multiple packages that depend on some
> library - you would have to bump every dependent package to make sure
> everyone gets the update. This is, apparently, by design.
>

If I'm thinking this through right, it's actually worse than that.  The 
FCam dev library is small and statically linked, so the it's the 
applications themselves that have a dependency on fcam-drivers.  So to 
guarantee that everyone who's using fcam-drivers gets an updated 
version, all applications that use it must release new versions with new 
version numbers for fcam-drivers, since any given user may have only one 
such app installed.

Since FCam is a publicly-available API that we're trying to promote, 
we're expecting third parties to write applications that depend on 
fcam-drivers.  That means not all apps will be ours, and we can't do the 
update for them, leaving some users with buggy versions.  Already, the 
HDR and low-light programs are apps by our collaborators at Nokia 
Research, and I don't have any ability to update them.

This seems like an unfortunate situation in terms of bug fixes and so on 
- we think fcam-drivers is pretty stable, so hopefully we don't have to 
update it again anytime soon!

Eino-Ville (Eddy) Talvala
Computer Graphics Lab
Stanford University