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This is a binding for libdbus 1.0 (and hopefully 1.2.x).
Goals & status
|call methods in other processes, and get the return values||yes|
|call methods in other processes asynchronously, and the return values come back to a callback later|
|register a procedure as a handler for a service/method||yes|
|assign a path to a TinyClos object and map applicable generic functions as dbus methods|
|create proxy objects matching remote objects|
|discover services locally|
|discover services on nearby machines|
|user code to do any of the above should be minimal: abstract away the orthogonal extra steps (open a connection, start a polling thread, etc.)||yes|
libdbus and its headers
libdbus has historically had a GPL license. The dbus homepage refers to an incomplete "planned X11/MIT license change due to a couple of license holders who have yet to respond. For the most part this license change is being pursued to simplify licensing issues and fix a couple of licensing corner cases. When this happens D-Bus will be released under the 1.2.0 version." So this egg is released under the MIT license, however if you link it with a version prior to 1.2.0, then you are probably bound by the terms of the GPL.
These are in the test subdirectory in svn. (Not included in the egg itself at this point)
Examples you can test with QT
QT includes a DBUS remote-controlled car example. E.g. it might be located in /usr/share/qt4/examples/qdbus/remotecontrolledcar/car depending on your distro. If you run the car, you can cause the wheels of the car to turn to the right by doing this:
(use dbus) (define rc-car-context (dbus:make-context service: 'com.trolltech.CarExample interface: 'com.trolltech.Examples.CarInterface path: '/Car)) (dbus:send rc-car-context "turnRight")
That example called a method but it did not expect any return values.
Now suppose you want to simulate the car, so you can use the above example to control your own car rather than the QT one:
(use dbus) (define (turn-right) (printf "car is turning to the right~%")) (define (turn-left) (printf "car is turning to the left~%")) (define rc-car-context (dbus:make-context service: 'com.trolltech.CarExample path: '/Car interface: 'com.trolltech.Examples.CarInterface )) (dbus:register-method rc-car-context "turnRight" turn-right) (dbus:register-method rc-car-context "turnLeft" turn-left)
dbus:register-method starts a polling loop. So you can then run the program above which does dbus:send, and you will see the appropriate printf statement execute asynchronously when the message is received.
Examples based on the DBus Tutorial
The next example, taken from the tutorial, shows how to deal with return values. First the "listener" program which will answer the query:
(use dbus) (define (query . params) (printf "got a query; params: ~s~%" params) ;; the response to the query: `(#t 42)) (define ctxt (dbus:make-context service: 'test.method.server interface: 'test.method.Type path: '/test/method/Object)) (dbus:register-method ctxt "Method" query)
And now the program which sends a query and prints out the response:
(use dbus) (define ctxt (dbus:make-context service: 'test.method.server interface: 'test.method.Type path: '/test/method/Object)) (let ([response (dbus:send-and-await-reply ctxt "Method" "query" "What is the meaning of life, the universe and everything?") ]) (printf "sent a very important query with a known answer; got flippant response ~s~%" response) (if (and (list? response) (eq? 42 (cadr response))) (printf "bingo!~%") (printf "and the answer is wrong too! Bad supercomputer, bad!~%")))