D-Bus in Java problem

Matthew Johnson dbus at matthew.ath.cx
Fri Jul 12 07:19:15 PDT 2013

On Wed Jul 10 14:57, Martin H wrote:
> Hi, I am trying to communicate with a C++ Qt D-Bus daemon with a java
> program to call a method, which returns a string. First I checked the
> actual availability of the method via D-Bus with the tool D-Feet. So I am
> able to call the method with this tool and I receive the result I expect.
> The problem is, when I use dbus-java-2.7, I get the following error:
> org.freedesktop.dbus.exceptions.DBusExecutionException:
> com.sun.proxy.$Proxy2.get_perf_data(org.freedesktop.dbus.UInt64,
> org.freedesktop.dbus.UInt64)
>     at org.freedesktop.dbus.AbstractConnection.callMethodAsync(Unknown
> Source)
>     at
> de.tuberlin.kbs.performancemonitor.DataThread.retrieveDataFromDBus(DataThread.java:123)
>     at de.tuberlin.kbs.performancemonitor.DataThread.run(DataThread.java:59)
>     at java.lang.Thread.run(Thread.java:722)
> It is kind of obvious, that the "Unknown Source" might be the problem, but
> I am hopelessly lost trying to determine the reason for this. For creation
> of the connection and the interface I use the following:

Unknown Source here just says that it was compiled without debug symbols.

> UInt64 from = new UInt64(0);
> UInt64 to = new UInt64(0);
> dBusConnection = DBusConnection.getConnection(DBusConnection.SESSION);
> dBusInterface =
> dBusConnection.getPeerRemoteObject("de.tuberlin.kbs.performancemonitor",
> "/");
> if(dBusInterface.isRemote())
>     dBusConnection.callMethodAsync(dBusInterface,
> "get_perf_data",from,to);

> The object IS remote and the method call produces the mentioned error.

Out of interest, why are you using callMethodAsync rather than a synchronous
call? Have you defined the java class matching your Interface?

MyInterface mi = (MyInterface) dbusConnection.getPeerRemoteObject(....);
mi.get_perf_data(from, to) would be the normal way to call here.

I can't remember if callMethodAsync works without a defined interface available, so that could be the problem.

Was there any other error message in the Exception? I'd expect something else. Did you miss something in your paste?

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 835 bytes
Desc: Digital signature
URL: <http://lists.freedesktop.org/archives/dbus/attachments/20130712/2a494983/attachment.pgp>

More information about the dbus mailing list