Persistent data with KDED (or KIOD) and a KIO Slave?

[David Faure]

On dimanche 8 octobre 2017 15:22:00 CEST Mark Gaiser wrote:
> But then i still miss one rather important detail that i can't really find
> anywhere..
> Lets say I have that module and call it "tags2" (as Baloo already has tags,
> therefore tags2 to prevent naming issues).
> 
> So i make a dbus service file named:
>   Name=org.kde.tags2
> 
> And in the "tags2.json" i put:
> 
> {
>     "KPlugin": {
>         "Description": "Put tags on files and folders.",
>         "Name": "Tags 2",
>         "ServiceTypes": [
>             "KDEDModule"
>         ]
>     },
> 
>     "X-KDE-DBus-ModuleName": "tags2",
>     "X-KDE-DBus-ServiceName": "org.kde.tags2"
> }
> 
> What do i do in the client side code to start this module?

You just make a DBus call to the service org.kde.tags, with
object path /modules/tags2. That will start kiod if needed,
load the module, and make the call.

The best solution for this is with type safety rather than without,
i.e. generating C++ from the DBus xml file. See e.g.
kio/core/kpasswdserverclient.cpp which makes calls to the kiod kpasswdserver 
module using the generated OrgKdeKPasswdServerInterface class.
qt5_add_dbus_interface() is the cmake function for doing that.

> That "client side" can be an IO slave, but it can also be some special Tags
> helper classes to create a new tag name with description and icon or such.

Sure, anyone can make dbus calls.

> I need to call something to trigger KIOD to start this module, but i can't
> figure out what.
> 
> How do i see qCDebug output from kiod plugins anyhow?

In ~/.xsession-errors, or by killing kiod and restarting it in a terminal.

-- 
David Faure, faure at kde.org, http://www.davidfaure.fr
Working on KDE Frameworks 5