[AppStream] Requiring a specific version of something

[Richard Hughes]

On 20 December 2016 at 14:25, Matthias Klumpp <matthias at tenstral.net> wrote:
> Flatpak too? That would mean I was right the whole time with my more
> modular approach to bundling, yay ^^ - why doesn't it feel better? :P

Well, flatpak apps can depend on an SDK or Runtime (or both) but not each other.

> But a firmware can be for many devices, shouldn't we define which
> firmware the version comparison should act on? Or does "firmware" mean
> "the current installed firmware"?

Exactly that, for cases where you can upgrade 1.x.x to 1.y.y but not to 2.x.x.

> Crazy. I never thought this would be that complex. I think I just need
> to blindly trust you on that ^^

So you'd think people would just use DFU. Apparently not :)
https://blogs.gnome.org/hughsie/2015/11/14/fwupd-and-dfu/

> AppStream/libas is a bit more advanced in that regard:
> https://github.com/ximion/appstream/blob/master/src/as-utils.c#L933
> (based on what RPM has) - but I always wanted to edit the algorithm
> slightly to be less surprising for both DPKG and RPM users.

I tried to avoid being magic by taking the "least common denominator"
approach. I'm open for ideas.

> Will have have a dependency solver in AppStream at some point? I kind
> of hope that this won't happen...

I hope not.

> Or
> <requires>
>   <firmware version="1.1" compare="lower-equal"/>
> </requires>

This would match the provides style with a few tweaks:

<provides>
<firmware type="flashed">84f40464-9272-4ef7-9399-cd95f12da696</firmware>
</provides>

akin to:

<requires>
  <firmware type="bootloader" compare="lower-equal" version="1.1"/>
  <id type="component">org.foo.Bar</id>
</requires>

or even:

<requires>
  <firmware type="bootloader" compare="version-equal-or-lower">1.1</firmware>
  <id>org.foo.Bar</id>
</requires>

Richard