Detecting appstream scheme support ; end-user-oriented "About AppStream" page (was: Re: Add "Install via AppStream" links to applications on kde.org)

[Matthias Klumpp]

2016-12-19 1:00 GMT+01:00 Friedrich W. H. Kossebau <kossebau at kde.org>:
> Am Sonntag, 18. Dezember 2016, 22:50:23 CET schrieb Albert Astals Cid:
>> El dissabte, 17 de desembre de 2016, a les 0:17:22 CET, Friedrich W. H.
>>
>> Kossebau va escriure:
>> Is it possible to detect if the browser has a handler for the appstream:
>> scheme and if not don't show the link at all?
>
> At least from a quick search there is no simple querying of the supported
> protocols possible. Only saw hacks of the kind which made me try to stay out
> of web development.
>
> I would agree only showing the link active in browsers where the protocol
> works would be nicer. I can just tell myself e.g. irc:// urls in the same box
> also have a similar fate.

I am actually rather happy about that, the less information a browser
exposes to the webpage by default, the harder it gets to use the
information for tracking or to detect vulnerable systems.

> @Matthias & Co: What other web pages/sites are already making use of such
> appstream links? How do they handle it?

So far I've only seen very few, mainly on Wiki pages or private pages
at GNOME. All of them show these links unconditionally.
What you could do is detect whether the user is running Linux and if
not, hide the link. As of no, there is no Windows client consuming
this data that I know of.

> That left aside, most people surely still have no clue what "AppStream" is.
>
> So it could make sense to have a small note mark to the right of the
> appstream:id link for the "What the heck is Appstream" use-case, so people
> could click/tap the button and learn about AppStream (or already learn a
> little in a tooltip, though a separate note mark still is needed for discovery
> and touch UI browsing).

About that: I wonder whether it would actually make more sense to show
a link like "Open in Software Center" or "Open in KDE Discover" or
anything more descriptive... AppStream is a rather technical term, and
if users need to read a page to know what it does, the links are less
useful.

> @Matthias: is there some distro-agnostic end-user website/page this "About
> AppStream" symbol could link to?
> Only found https://www.freedesktop.org/software/appstream/docs/chap-AppStream-About.html but that is not really consumable by Sue and Joe -No-Code-Please-
> User.

We could make one...
https://www.freedesktop.org/wiki/Distributions/AppStream/ exists, but
since AppStream is a rather technical project, I don't think we even
should attempt to explain it for users who will never see the metadata
(what is metadata anyway? - we'd even need to explain that first).
IMHO some short explanation maybe in form of a small "what is this?"
info on the webpage or a tooltip which shows something like "Open the
page of this application in the software center of your operating
system" would be much more useful. And since at time *every* software
center on Linux, including the one on Ubuntu, uses AppStream metadata
and appstream-IDs, we can simplify and generalize a lot :-)

Cheers,
    Matthias

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