The Low Level Interface — dbus-next 0.2.3 documentation (original) (raw)

Message

The low-level interface allows you to work with messages directly through the MessageBus with the Message class. This might be useful in the following cases:

Implementing an application that works with DBus directly like dbus-send(1) or dbus-monitor(1).
Creating a new implementation of the BaseMessageBus.
Creating clients or services that use an alternative to the standard DBus interfaces.

The primary methods and classes of the low-level interface are:

Mixed use of the low and high level interfaces on the same bus connection is not recommended.

example

Call a standard interface

bus = await MessageBus().connect()

msg = Message(destination='org.freedesktop.DBus', path='/org/freedesktop/DBus', interface='org.freedesktop.DBus', member='ListNames', serial=bus.next_serial())

reply = await bus.call(msg)

assert reply.message_type == MessageType.METHOD_RETURN

print(reply.body[0])

example

A custom method handler. Note that to receive these messages, you must add a match rule for the types of messages you want to receive.

bus = await MessageBus().connect()

reply = await bus.call( Message(destination='org.freedesktop.DBus', path='/org/freedesktop/DBus', member='AddMatch', signature='s', body=["member='MyMember', interface='com.test.interface'"]))

assert reply.message_type == MessageType.METHOD_RETURN

def message_handler(msg): if msg.interface == 'com.test.interface' and msg.member == 'MyMember': return Message.new_method_return(msg, 's', ['got it'])

bus.add_message_handler(message_handler)

await bus.wait_for_disconnect()

example

Emit a signal

bus = await MessageBus().connect()

await bus.send(Message.new_signal('/com/test/path', 'com.test.interface', 'SomeSignal', 's', ['a signal']))

example

Send a file descriptor. The message format will be the same when received on the client side. You are responsible for closing any file descriptor that is sent or received by the bus. You must set thenegotiate_unix_fd flag to True in the MessageBusconstructor to use unix file descriptors.

bus = await MessageBus().connect(negotiate_unix_fd=True)

fd = os.open('/dev/null', os.O_RDONLY)

msg = Message(destination='org.test.destination', path='/org/test/destination', interface='org.test.interface', member='TestMember', signature='h', body=[0], unix_fds=[fd])

await bus.send(msg)