10 CreateInterface

D-Bus provides a method to get introspection data on a remote object, which describes the interfaces, methods and signals it provides. This introspection data is in XML format19 . The library automatically provides XML introspection data on all objects which are exported by it. Introspection data can be used to create Java interface definitions automatically.

The CreateInterface20 class will automatically create Java source files from an XML file containing the introspection data, or by querying the remote object over D-Bus. CreateInterface can be called from Java code, or can be run as a stand alone program.

The syntax for the CreateInterface program is

CreateInterface [--system] [--session] [--create-files]  
                  <bus name> <object>  
CreateInterface [--create-files] <introspection-file.xml>

The Java source code interfaces will be written to the standard ouput. If the --create-files option is specified the correct files in the correct directory structure will be created.

10.1 Nested Interfaces

In some cases there are nested interfaces. In this case CreateInterface will not correctly create the Java equivalent. This is because Java cannot have both a class and a package with the same name. The solution to this is to create nested classes in the same file.

An example would be the Hal interface:

<interface name="org.freedesktop.Hal.Device">  
<interface name="org.freedesktop.Hal.Device.Volume">  

When converted to Java you would just have one file org/freedesktop/Hal/Device.java in the package org.freedesktop.Hal, which would contain one class and one nested class:

public interface Device extends DBusInterface {  
   public interface Volume extends DBusInterface {  
      ... methods in Volume ...  
   ... methods in Device ...