D-Bus - National Radio Astronomy Observatory · Gambas, Objective-C, and Ada Wednesday, June 19, 13. Architecture? Processes Attach to Bus & Get Address (e.g. edu.nrao.casa.clean)

D-BusOpen-Source IPC

Wednesday, June 19, 13

What Is It?

Multi-platform (Linux, OSX, Windows)Multi-language (Java, PHP, .NET, etc.)Small-footprintBus-basedStandard for IPC


Any Distinguishing Features?

Object Oriented - Methods and SignalsService DiscoveryIntrospectionBinary ProtocolSecureLarge Developer and User Base


Who Uses It?

All KDE users and Most GNOME usersPidgin, Skype and CUPS usersLinux HAL (Hardware Abstraction Layer)Any Linux System that Supports Hot Plugging Devices


Language Support?

Python, Qt, Java, Perl, C++, PHP, Pascal, .NET, Ruby, Scheme, Tcl, Squeak (smalltalk variant), Haskell, Ocaml, Gambas, Objective-C, and Ada


Architecture?

Processes Attach to Bus & Get Address (e.g. edu.nrao.casa.clean)

Processes Make Objects (services) Available (e.g. /casa/clean_server)

Objects Provide One or More Interfaces (e.g clean.multiscale)


Bindings We Care About (Python)

bus = dbus.SessionBus( )

obj = bus.get_object(‘edu.nrao.edu.clean’,’/casa/clean_server’)

proxy = dbus.Interface(obj,‘clean.multiscale’)


Bindings We Care About (Qt)

QDBusInterface proxy(‘edu.nrao.casa.clean’,’/casa/clean_server’,‘clean.multiscale’)

proxy.call(“method”, arg1, arg2, ...)


Bindings We Care About (C++ without Qt)

dbusxx-xml2cpp is used to generate abstract base classes (proxy and adaptor) from XML descriptionthe abstract base make it trivial to provide or access services on D-Bus


What about providing services (Python)

class Example(dbus.service.Object): def __init__(self, object_path): dbus.service.Object.__init__(self, bus, path)

@dbus.service.method(‘clean.multiscale’, ...) def methodname( self, ... ) <do-work-here>


What about providing services (Qt)

class adaptor : public QDBusAbstractAdaptor { Q_OBJECT Q_CLASSINFO( “D-Bus Interface”, “edu.nrao.casa.clean_server”);

QDBusVariant method( ... );


Bindings We Care About (C++ without Qt)

dbusxx-xml2cpp is used to generate abstract base classes (proxy and adaptor) from XML descriptionthe abstract base make it trivial to provide or access services on D-Bus


Supported Types

byte double

boolean string

int16 uint16

int32 uint32

int64 uint64

structure

array

variant

map

object path

signature

unix fd


Sometimes Things Change

complete configuration via an xml filemultiple authentication methods supported, including “external”timeouts, limits, security policiesmultiple transport methods, including pipes and sockets


Documents

D-Bus - National Radio Astronomy Observatory · Gambas, Objective-C, and Ada Wednesday, June 19, 13. Architecture? Processes Attach to Bus & Get Address (e.g. edu.nrao.casa.clean)