[Dev] Tizen 3 services: use case for multi user

Zaman, Imran imran.zaman at intel.com
Tue Sep 9 12:00:08 GMT 2014


Hi Dominig!

I am bit confused with the requirements for multi-user-multi-seat in Tizen Common. Can you please help us understand a bit so that we can evaluate if tlm can be changed to work on Tizen Common? Below are some questions if you can plz answer those?

Some basics to keep in mind before the questions,
1- As Jussi pointed out, "Seat" is a group of displays and input devices when weston, udev and systemd are used together.
2- When a user session is active, binding between user session and seat exist
3- At the moment, udev, systemd and weston are in use. Weston lacks multi-user-multi-seat behaviour right now.
4- For tizen IVI, when a user logs out on a seat, a guest user automatically logs in by tlm

Lets suppose that we have two seats 'S1' and 'S2', whereas 'S1' is a group of KB1, M1, D1 and 'S2' is a group of KB2, M2 and D2 (KB=Keyboard, M=Mouse, D=Display)

Q1- Can you please elaborate your understanding of a seat, display and input devices along with some example for Tizen Common?
Q2a- Is it a requirement to have more than one user sessions per seat in Tizen Common active simultaneously?
Q2b- If the answer to Q2a is 'Yes', can you please elaborate that how do you think that if e.g. users U1 and U2 both are logged in on Seat S1, then how would U1 and U2 can interact with S1 at the same time given that there is single keyboard, mouse and display?
Q3- What should be the behaviour if there are e.g. 2 users logged in on a seat 'S1', and both of them logs out, shall a guest user log in automatically on S1 in Tizen Common or ? 
Q4- Is it possible to document Tizen Common multi-user-multi-seat use case in detail with some basic flows (e.g. two users logged it on a single seat and wants to write a document simultaneously)?

Your help in this regard will be highly appreciated so that we can work out some possible solution for tizen Common. Thanks :-)

BR
imran
________________________________________
From: Dev [dev-bounces at lists.tizen.org] on behalf of Kaskinen, Tanu [tanu.kaskinen at intel.com]
Sent: 09 September 2014 12:24
To: jussi.laako at linux.intel.com
Cc: dev at lists.tizen.org
Subject: Re: [Dev] Tizen 3 services: use case for multi user

On Mon, 2014-09-08 at 15:14 +0300, Jussi Laako wrote:
> On 5.9.2014 11:53, Dominig ar Foll (Intel OTC) wrote:
> > Furthermore the requirement from Genivi is that a user application can
> > be moved from one seat to an other without disconnection, so the binding
> > between a seat an a user does not exist.
>
> Binding between session and seat does exist when session is active.
> Sessions can be suspended and re-seated, see logind APIs for details.

I looked at [1], and to me the documentation sounds like logind sessions
can't be re-seated. Firstly, the documentation for
org.freedesktop.login1.Manager.ActivateSession()
and .ActivateSessionOnSeat() says the following:

    ActivateSession() brings the session with the specified ID into
    the foreground. ActivateSessionOnSeat() does the same, but only
    if the seat id matches.

"Only if the seat id matches" sounds like the method isn't meant for
moving a session between seats, and I couldn't find any other method
that would do the moving.

Secondly, the org.freedesktop.login1.Session.Seat property is defined in
the introspection data as follows:

    @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
    readonly (so) Seat = ('', '/');

I'd guess EmitsChangedSignal("const") means that the property value
never changes, i.e. sessions are permanently tied to a single seat.

Have you actually tried moving a session between seats?

[1] http://www.freedesktop.org/wiki/Software/systemd/logind/

--
Tanu
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