Monitoring message returns, using dbus-monitor

Rob Taylor robtaylor at
Tue Mar 7 04:01:47 PST 2006

Robert McQueen wrote:
> Stefan Eilers wrote:
>>Currently I try to generte Sequence charts out of log-files, generated by the 
> It's probably not a good idea to try and do string parsing on the output
> of dbus-monitor - there's no guarantee that the format won't change or
> be modified, making your tool very fragile. It's not tricky to modify
> dbus-monitor or write something similar to output the format you need.

Perhaps giving dbus-monitor an '--output-xml' mode, where it outputs all
data using some xml schema would be advantageous?

>>dbus-monitor wants to receive message returns:
>>      dbus_bus_add_match (connection,
>>		          "type='method_return'",
>>		          &error);
>>Unfortunately this was never triggered. But I am sure, some of the function 
>>calls have to return anything.
>>Is this an known issue?
> It's not an issue, it's expected behaviour. Match rules are only used by
> the bus daemon when considering messages which have no recipient set.
> Messages like method calls and returns which are sent to a specific
> recipient are never sent to other bus members such as your dbus-monitor.
> One thing I've been thinking would be useful for debugging was some kind
> of bus snooping mode where you could set a flag in the bus daemon to
> make it allow certain clients (dbus-monitor) to have their match rules
> applied to other people's messages. Obviously you would only want this
> when testing so it should be some flag or environment variable which you
> set to change the bus daemon's behaviour.

A flag to dbus-daemon sounds the cleanest option to me.

Rob Taylor

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