Re: [systemd-devel] Dbus service
On Di, 18.09.18 15:07, deepan muthusamy (deepan.m2...@gmail.com) wrote: > What is the difference between dbus service and bus-activatable service? That's really a question to ask the D-Bus mailing list, not the systemd one. That said: a dbus service just means a service offering IPC interfaces via dbus. A bus-activatable service is a special kind of dbus service: it means the IPC interfaces are also offered while the service isn't started yet, and a client talking to such an IPC interface will then implicitly trigger starting of that service by doing so. "activatable" is just a fancy word for saying "can be started by", i.e. "triggred on-demand by". By building systems with bus-activatable services you build more robust, simpler and more efficient systems, as services don't have to run all the time, and clients don't have to know when precisely a service is started, but can talk to the service anyway, and rely that the dbus system will implicitly start any service that is not running yet, fully transparently. Examples for such bus-activable services are "policykit" for example, or systemd's own "hostnamed", both of which normally don't run, but when a client wants to talk to them are implicitly started. Lennart -- Lennart Poettering, Red Hat ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/systemd-devel
[systemd-devel] Dbus service
What is the difference between dbus service and bus-activatable service? ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] DBus service name encoding
On Mon, 04.03.13 19:00, Simon McVittie (simon.mcvit...@collabora.co.uk) wrote: On 04/03/13 14:31, Lennart Poettering wrote: So here's how to do this, it's very simple: every char outside of the A-Za-z0-9 range is escaped as _XY where XY is the numeric code of the char, as 2 char lower-case hex value. Note that _ itself is also escaped, to _5f. This sounds a lot like Telepathy's tp_escape_as_identifier(). Before freezing this as ABI, you might want to consider a couple of the more subtle points from that function: * we also escape any leading digit in the same way, so that a name starting with a digit is escaped as a valid bus name component (123.service - _3123_2eservice, because the D-Bus specification says Only elements that are part of a unique connection name may begin with a digit) * for completeness, we also escape into _ (because a zero-length string is not a valid D-Bus name component) This results in its output being a valid D-Bus bus-name element, interface-name element, member, and object-path element, and also a valid C identifier. Thanks for the suggestions! I have now updated systemd to follow the same logic in these corner cases. I also added test cases so that this should be pretty much set in stone now. Lennart -- Lennart Poettering - Red Hat, Inc. ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] DBus service name encoding
On Sun, 03.03.13 19:06, David Strauss (da...@davidstrauss.net) wrote: I can't find any documentation on how service names get encoded for DBus. It looks pretty close to URL encoding with underscores instead of percent signs. If I can get a definitive answer, I'll update the wiki. If I can't, I can, of course, dive into the source. This hasn't been documented since it so far wasn't part of the official ABI. So far you were supposed to invoke GetUnit() with an unescaped unit name, and it would return you the (escaped) bus path for it. Now, a while back systemctl was updated to simply do the escaping on the client side, to get rid of this roundtrip. systemctl of course is shipped with systemd, so it's not a problem for it to make use of this undocumented behaviour. That said, we could (and probably should) just open this up for external users too. So here's how to do this, it's very simple: every char outside of the A-Za-z0-9 range is escaped as _XY where XY is the numeric code of the char, as 2 char lower-case hex value. Note that _ itself is also escaped, to _5f. This is implemented in bus_path_escape() in src/shared/util.c. If you want to make use of it, please update the wiki dbus docs for the PID 1 interfaces, and document this there to make this official ABI, and refer to the sources (and maybe this mail). Please also add a comment line to the sources referring back to the wiki, so that people who change bus_path_escape() are aware that this is something that is part of the documented ABI. Lennart -- Lennart Poettering - Red Hat, Inc. ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] DBus service name encoding
On 04/03/13 14:31, Lennart Poettering wrote: So here's how to do this, it's very simple: every char outside of the A-Za-z0-9 range is escaped as _XY where XY is the numeric code of the char, as 2 char lower-case hex value. Note that _ itself is also escaped, to _5f. This sounds a lot like Telepathy's tp_escape_as_identifier(). Before freezing this as ABI, you might want to consider a couple of the more subtle points from that function: * we also escape any leading digit in the same way, so that a name starting with a digit is escaped as a valid bus name component (123.service - _3123_2eservice, because the D-Bus specification says Only elements that are part of a unique connection name may begin with a digit) * for completeness, we also escape into _ (because a zero-length string is not a valid D-Bus name component) This results in its output being a valid D-Bus bus-name element, interface-name element, member, and object-path element, and also a valid C identifier. S ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] DBus service name encoding
On Mon, Mar 4, 2013 at 11:00 AM, Simon McVittie simon.mcvit...@collabora.co.uk wrote: Before freezing this as ABI, you might want to consider a couple of the more subtle points from that function Considering that those two suggestions cover cases not yet handled by systemd's still-informal specification, I see no reason to object. -- David Strauss | da...@davidstrauss.net | +1 512 577 5827 [mobile] ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
[systemd-devel] DBus service name encoding
I can't find any documentation on how service names get encoded for DBus. It looks pretty close to URL encoding with underscores instead of percent signs. If I can get a definitive answer, I'll update the wiki. If I can't, I can, of course, dive into the source. -- David Strauss | da...@davidstrauss.net | +1 512 577 5827 [mobile] ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
