Question on service activation

[Kevin Krammer]

Hi all,

Yesterday another developer (Hi Cleso!) and me had a discussion about service 
activation based on target functionality, i.e. knowing which interface one 
would like to use.

Examples from the Maemo documentation and an activation tutorial linked from 
the D-Bus tutorial suggest that interface name == D-Bus name == object path 
(with slash as separator), e.g. a .service file specifying a 
service "org.example.Foo" will result in a process available at D-Bus 
name "org.example.Foo", with an object at "/org/example/Foo" having the 
interface "org.example.Foo"

This looks very handy, since, assuming a dynamic configuration as discussed by 
Havoc and Thiago a couple of weeks ago, would allow applications to just make 
calls to common interface and be relatively sure that a service will be 
started if not yet running.

However, we weren't sure how service providers (i.e. processes with a D-Bus 
connection providing interface implementations) would specify multiple 
interfaces.

For example consider PIM interfaces (kept short to ease typing): pim.EMail, 
pim.Contacts, pim.Calendar.

A "just email" application like Thunderbird would probably just implement 
pim.EMail and pim.Contacts, a full PIM suite like Evolution would implement 
all.

(1) If none if the is running yet and an application would make a call to 
pim.Contacts, will the bus wait until it has registered all its names?

(2) Is there a race condition if two applications activate two different 
services?

(3) If Evolution is the default handler as configured by the desktop, can 
Thunderbird be prevented from claiming the default names if started manually?

Thanks,
Kevin
-- 
Kevin Krammer, KDE developer, xdg-utils developer
KDE user support, developer mentoring
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