diff options
Diffstat (limited to 'doc/dbus-specification.xml')
| -rw-r--r-- | doc/dbus-specification.xml | 33 |
1 files changed, 29 insertions, 4 deletions
diff --git a/doc/dbus-specification.xml b/doc/dbus-specification.xml index d8e9911f..41d3fb9b 100644 --- a/doc/dbus-specification.xml +++ b/doc/dbus-specification.xml @@ -2290,9 +2290,10 @@ <title><literal>org.freedesktop.DBus.Peer</literal></title> <para> The <literal>org.freedesktop.DBus.Peer</literal> interface - has one method: + has two methods: <programlisting> org.freedesktop.DBus.Peer.Ping () + org.freedesktop.DBus.Peer.GetMachineId (out STRING machine_uuid) </programlisting> </para> <para> @@ -2300,9 +2301,33 @@ <literal>org.freedesktop.DBus.Peer.Ping</literal>, an application should do nothing other than reply with a <literal>METHOD_RETURN</literal> as usual. It does not matter which object path a ping is sent to. The - reference implementation should simply handle this method on behalf of - all objects, though it doesn't yet. (The point is, you're really pinging - the peer process, not a specific object.) + reference implementation handles this method automatically. + </para> + <para> + On receipt of the <literal>METHOD_CALL</literal> message + <literal>org.freedesktop.DBus.Peer.GetMachineId</literal>, an application should + reply with a <literal>METHOD_RETURN</literal> containing a hex-encoded + UUID representing the identity of the machine the process is running on. + This UUID must be the same for all processes on a single system at least + until that system next reboots. It should be the same across reboots + if possible, but may change due to reconfiguration or hardware changes. + It does not matter which object path a GetMachineId is sent to. The + reference implementation handles this method automatically. + </para> + <para> + The UUID must contain 128 bits of data and be hex-encoded (meaning, the hex + string contains 32 ASCII characters). The hex-encoded string may not contain + hyphens or other non-hex-digit characters, and it must be exactly 32 characters long. + To generate a UUID, the recommended algorithm is to put the current time in seconds + since the UNIX epoch in the last 32 bits of the UUID, and to put randomly-generated bits + in the first 96 bits of the UUID. + </para> + <para> + The UUID is intended to be per-instance-of-the-operating-system, so may represent + a virtual machine running on a hypervisor, rather than a physical machine. + Basically if two processes see the same UUID, they should also see the same + shared memory, UNIX domain sockets, process IDs, and other features that require + a running OS kernel in common between the processes. </para> </sect2> |