Re: [bus1-devel] dbus-broker Wwithout systemd?

[David Rheinsberg]

Hi

On Sun, Apr 14, 2019 at 9:53 AM <did...@slint.fr> wrote:
>
> Howdy,
>
> I am the maintainer of the Slint distribution, http://slint.fr/wiki//fr/start
>
> I have heard that dbus-broker could enhance performances, especially when using a11y software.
>
> This does interest me as Slint is fully accessible with Braille and speech, including in graphical mode ustng the at-* stack and Orca.
>
> But if I understand well dbus-broker can' be used without systemd, but Slint (Slackware derivative) does not include systemd.
>
> Please confirm or infirm that dbus-broker needs (and will always need) systemd.

You can see the list of dependencies in the README file [1]. For the
`dbus-broker` binary this would be a recent linux kernel and a libc.
The `dbus-broker` project provides an example launcher for
compatibility with `dbus-daemon`. This launcher, as listed in the
README file, additionally depends on `systemd` and `expat`. To my
knowledge, there currently is no other launcher with dbus-daemon
compatibility, though.

The `dbus-broker` project provides a standalone implementation of a
D-Bus Message Bus. It was intentionally designed to not place any
restrictions on its surroundings (and as such does not mandate any
dependencies other than a linux kernel). However, someone has to
integrate it into existing distribution setups. The
`dbus-broker-launch` binary provides such an integration for the
Fedora Distribution and other compatible ones.

Thanks
David

[1] https://github.com/bus1/dbus-broker/blob/master/README.md

[Didier Spaier]

Hi,

Thanks for your answer, David.

On 14/04/2019 13:32, David Rheinsberg wrote:
> The `dbus-broker` project provides an example launcher for
> compatibility with `dbus-daemon`. This launcher, as listed in the
> README file, additionally depends on `systemd` and `expat`. To my
> knowledge, there currently is no other launcher with dbus-daemon
> compatibility, though.
>
> The `dbus-broker` project provides a standalone implementation of a
> D-Bus Message Bus. It was intentionally designed to not place any
> restrictions on its surroundings (and as such does not mandate any
> dependencies other than a linux kernel). However, someone has to
> integrate it into existing distribution setups. The
> `dbus-broker-launch` binary provides such an integration for the
> Fedora Distribution and other compatible ones.

Slackware (and Slint, as Slackware derivative) currently uses
as daemon manager a shell script /etc/rc.d/rc.messagebus (attached).

can I just use this script, possibly with some changes, and continue
to use dbus-dameon, instead of switching to dbus-broker-launch?

If the answer is yes, could you please give me some pointers to
help me find out which changes would be necessary?

Thanks and best regards,

Didier

[David Rheinsberg]

Hi

On Sun, Apr 14, 2019 at 2:06 PM Didier Spaier <did...@slint.fr> wrote:
> can I just use this script, possibly with some changes, and continue
> to use dbus-dameon, instead of switching to dbus-broker-launch?
>
> If the answer is yes, could you please give me some pointers to
> help me find out which changes would be necessary?

There seems to be a misunderstanding: `dbus-broker` is an
implementation of the D-Bus specification, just like `dbus-daemon` is.
However, the original `dbus-daemon` provides a lot more tooling around
it, including parsing service files, handling service activation,
parsing configuration files and providing a message bus policy. These
are all features beyond the D-Bus specification, and thus are not
standardized in any way.

A pure bus implementation like `dbus-broker` does not get you
anywhere. You need some integration into the actual system. With
`dbus-broker-launch` we provide this for systems based on systemd. The
original `dbus-daemon` had all this functionality included in its
base, rather than splitting both apart.

If you intend to employ `dbus-broker` over `dbus-daemon`, there are 2 options:

1) Use the provided launcher `dbus-broker-launch`, which is tailored
for systemd-based distributions.
2) Write your own launcher. This very likely requires parsing bus
configuration files, service configuration files, and the message bus
policy, and then spawning your own instance of `dbus-broker`. This is
in no way a trivial task. However, it is completely unrelated to
D-Bus, which is why we don't believe this belongs into `dbus-broker`.
The information to write a launcher yourself, and how to interact with
`dbus-broker` instances is documented in the `dbus-broker(1)`
man-page.

Thanks
David

[Didier Spaier]

Hi,

On 14/04/2019 16:56, David Rheinsberg wrote:
> If you intend to employ `dbus-broker` over `dbus-daemon`, there are 2 options:
>
> 1) Use the provided launcher `dbus-broker-launch`, which is tailored
> for systemd-based distributions.
> 2) Write your own launcher. This very likely requires parsing bus
> configuration files, service configuration files, and the message bus
> policy, and then spawning your own instance of `dbus-broker`. This is
> in no way a trivial task. However, it is completely unrelated to
> D-Bus, which is why we don't believe this belongs into `dbus-broker`.
> The information to write a launcher yourself, and how to interact with
> `dbus-broker` instances is documented in the `dbus-broker(1)`
> man-page

None of these options feasible now or in the short term, so I will
keep dbus-daemon in Slint for now.

Anyway, thanks for the clarification.

Best regards,

Didier