From kde-pim  Mon May 12 09:50:40 2008
From: Sander van Grieken <sander () 3v8 ! net>
Date: Mon, 12 May 2008 09:50:40 +0000
To: kde-pim
Subject: Re: [Kde-pim] Akonadi D-Bus interface renaming: remaining issues
Message-Id: <200805121150.41875.sander () 3v8 ! net>
X-MARC-Message: https://marc.info/?l=kde-pim&m=121058587902919

On Sunday 11 May 2008 15:54:46 Kevin Krammer wrote:
> On Sunday 11 May 2008, Sander van Grieken wrote:
> > Why should the server have control of the GUI directly (i.e. have a
> > concept of a UI or Window)? IMHO a server should just send out
> > signals/notifications on which the UI should act. If a 'conversation'
> > needs to take place, the server could send out a signal/notification
> > synchronously, which triggers the UI to perform the conversation with the
> > user, and then returns a result from the conversation.
>
> Right, this is part of the current interface. We probably could split that
> in two interfaces, one for the reporting and one for getting a parent
> window ID.
>
> > This way the server can stick to the domain model, and the UI
> > implementation does not need to conform to and expose a UI interface.
>
> The server doesn't use any UI, but resources or agents might, e.g. data
> type specific conflict resolving.
>
> In a traditional setup, where one application has direct control over the
> backends it uses, it can always pass its window ID at any call which
> results in backend actions.
> However, in an Akonadi setup, resources work on their own or are triggered
> by the server (e.g. through cache policies).
>
> Of course there might be better ways of solving that, we'll appreciate any
> suggestions.
>
> > It all sounds a bit like a (indirect, through dbus) circular dependency
> > to me.
>
> Hmm, I am not sure that there is any cycle. The UI part just provides a
> service to the Akonadi setup, it doesn't need Akonadi itself.
>
> Cheers,
> Kevin

It boils down to using a callback pattern (backend actively looking up a dbus 
interface and calling it) vs. an observer pattern (backend exposes signals to 
which the UI subscribes). 

Still, I see no use for a 'window ID' in the backend either way.

grtz,
Sander
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