Snappy capabilities, in baby steps

Gustavo Niemeyer gustavo.niemeyer at
Fri Nov 13 17:02:17 UTC 2015

On Fri, Nov 13, 2015 at 2:47 PM, Ted Gould <ted at> wrote:

> Uhm, okay. Typically I prefer to map the landscape first, but okay.

I understand, and I hope you understand where I'm coming from as well.

So from Zygumnt's thread it sounds like there's going to be a tag cloud
> attached to each snap. I'm guessing that this is going to include kernel,
> gadget and framework snaps. They'll export which tags they support. Will
> the tags be centrally defined or are we hoping for some sort of emergent
> behavior here? How will we handle conflicting tags?

The terminology in use is that there's a capability name which is a unique
identifier in its context (e.g. the snap) and there's a capability type
which defines its meaning. We want to make capability types extensible, but
they must be centrally approved since there are security concerns
associated with it.

> For the cases where versioning is important, how will that be handled. For
> instance being able to support OpenGL could mean standard GL of various
> versions or GLes of various versions. For games which versions the HW can
> support can be very important.

The capability type defines what behavior is allowed and expected. There
will be metadata associated with the capability, so in cases where the
capabilities are very similar they may end up being defined as a single
capability type with differing metadata. In other cases, they may be
different types.

> There was a mention of passing metadata, which way will the metadata
> transfer occur? Both? What is the lifecycle and policy for handing that
> passing of metadata? Does it require a particular format or is that to be
> decided by the framework and/or application involved in the exchange?

There will be a particular format and protocol for exchanging the data.
We're not there yet, though.

I hope that'll start the conversation some.

Hope that helps. Let us know if you have more.

gustavo @
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