[bsder]

In what way is DBus better than something like Cap'n Proto? What does it cover and not cover? What other IPC/RPCs compete with it?

When I start seeing C++, AUTH, and Kerberos I start getting concerned.

When I don't find a Python-only module for something claimed to be "simple", I start getting very concerned: https://pypi.org/project/dbus-python/

[charcircuit]

>In what way is DBus better than something like Cap'n Proto?

In this specific context it is less about being better and more about being the standard for apps that are part of the Linux desktop except for Wayland which has its own. There are benefits in developers all being familiar with dbus, not having to use different clients for each program you want to talk to, it is easier to secure, etc.

[bsder]

> There are benefits in developers all being familiar with dbus, not having to use different clients for each program you want to talk to, it is easier to secure, etc.

Is it those things?

People don't seem to use DBus at all outside of Linux. That would seem to imply that, by and large, it isn't those things. And the fact that someone on Linux in exactly the situation where it should be used wasn't willing to use it suggests that maybe there are significant issues.

[charcircuit]

>People don't seem to use DBus at all outside of Linux.

Because it is a part of freedesktop, a project largely about creating software and specifications for the Linux desktop. Windows has COM. Mac / iOS have XPC. Android has Binder.

> And the fact that someone on Linux in exactly the situation where it should be used wasn't willing to use it suggests that maybe there are significant issues.

It is from cultural and educational issues. It isn't just a coincidence that all operating systems I listed above have a standard IPC mechanism that they use for services.