Current File : //usr/share/doc/gjs/examples/dbus-service.js
// SPDX-License-Identifier: MIT OR LGPL-2.0-or-later
// SPDX-FileCopyrightText: 2020 Andy Holmes <andrew.g.r.holmes@gmail.com>
import GLib from 'gi://GLib';
import Gio from 'gi://Gio';
/*
* An XML DBus Interface
*/
const ifaceXml = `
<node>
<interface name="org.gnome.gjs.Test">
<method name="SimpleMethod"/>
<method name="ComplexMethod">
<arg type="s" direction="in" name="input"/>
<arg type="u" direction="out" name="length"/>
</method>
<signal name="TestSignal">
<arg name="type" type="s"/>
<arg name="value" type="b"/>
</signal>
<property name="ReadOnlyProperty" type="s" access="read"/>
<property name="ReadWriteProperty" type="b" access="readwrite"/>
</interface>
</node>`;
// An example of the service-side implementation of the above interface.
class Service {
constructor() {
this.dbus = Gio.DBusExportedObject.wrapJSObject(ifaceXml, this);
}
// Properties
get ReadOnlyProperty() {
return 'a string';
}
get ReadWriteProperty() {
if (this._readWriteProperty === undefined)
return false;
return this._readWriteProperty;
}
set ReadWriteProperty(value) {
if (this.ReadWriteProperty !== value) {
this._readWriteProperty = value;
// Emitting property changes over DBus
this.dbus.emit_property_changed(
'ReadWriteProperty',
new GLib.Variant('b', value)
);
}
}
// Methods
SimpleMethod() {
print('SimpleMethod() invoked');
}
ComplexMethod(input) {
print(`ComplexMethod() invoked with "${input}"`);
return input.length;
}
// Signals
emitTestSignal() {
this.dbus.emit_signal(
'TestSignal',
new GLib.Variant('(sb)', ['string', false])
);
}
}
// Once you've created an instance of your service, you will want to own a name
// on the bus so clients can connect to it.
let serviceObj = new Service();
let serviceSignalId = 0;
function onBusAcquired(connection, _name) {
// At this point you have acquired a connection to the bus, and you should
// export your interfaces now.
serviceObj.dbus.export(connection, '/org/gnome/gjs/Test');
}
function onNameAcquired(_connection, _name) {
// Clients will typically start connecting and using your interface now.
// Emit the TestSignal every few seconds
serviceSignalId = GLib.timeout_add_seconds(GLib.PRIORITY_DEFAULT, 3, () => {
serviceObj.emitTestSignal();
return GLib.SOURCE_CONTINUE;
});
}
function onNameLost(_connection, _name) {
// Clients will know not to call methods on your interface now. Usually this
// callback will only be invoked if you try to own a name on DBus that
// already has an owner.
// Stop emitting the test signal
if (serviceSignalId > 0) {
GLib.Source.remove(serviceSignalId);
serviceSignalId = 0;
}
}
let ownerId = Gio.bus_own_name(
Gio.BusType.SESSION,
'org.gnome.gjs.Test',
Gio.BusNameOwnerFlags.NONE,
onBusAcquired,
onNameAcquired,
onNameLost
);
// Start an event loop
let loop = GLib.MainLoop.new(null, false);
loop.run();
// Unowning names works just like disconnecting, but note that `onNameLost()`
// will not be invoked in this case.
Gio.bus_unown_name(ownerId);
if (serviceSignalId > 0) {
GLib.Source.remove(serviceSignalId);
serviceSignalId = 0;
}
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