1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
|
/****************************************************************************
**
** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:FDL$
** GNU Free Documentation License
** Alternatively, this file may be used under the terms of the GNU Free
** Documentation License version 1.3 as published by the Free Software
** Foundation and appearing in the file included in the packaging of
** this file.
**
** Other Usage
** Alternatively, this file may be used in accordance with the terms
** and conditions contained in a signed written agreement between you
** and Nokia.
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
/*!
\example servicebrowser
\title Service Browser Example
This example shows how to use the Service Framework to:
\list
\o Register and unregister services
\o Find available services
\o Find the interfaces that are implemented by a service
\o Look up the attributes for an interface implementation using the meta-object system
\o Set a default interface implementation
\endlist
\image servicebrowser.png Screenshot of the Service Browser example
The application window is split into three panes.
The top-left pane shows all the services that are registered within the Service Framework. For this example, the \l{File Manager Plugin Example}{filemanagerplugin} and \l {Bluetooth Transfer Plugin Example}{bluetoothtransferplugin} services included in the \c examples/ directory have been registered, and so are visible in this pane.
The bottom-left pane shows the interfaces implemented by the service selected in the top-left pane. Each entry in this list shows:
\list
\o The name and version of the implemented interface
\o The service that provides this implementation (in brackets)
\o Whether the implementation is the default for its interface
\endlist
The right-hand pane shows the attributes of an interface implementation that are invokable through the Qt meta-object system. Such attributes include signals, slots, properties and methods marked with the \c Q_INVOKABLE macro. If the "Selected implementation" radio button is checked, this view shows the attributes of the selected implementation in the bottom-left pane; otherwise, it shows the attributes of the \i default implementation for the interface of the selected implementation.
The following steps have to be done manually if this application is to be executed in Qt Simulator:
\list
\o Plugin based services (\c filemanagerplugin and \c bluetoothtransferplugin) must be manually copied
to the same directory as the \c servicebrowser executable.
\o A new \c xmldata folder must be created in the same directory as \c servicebrowser
executable, and xml files of service plugins (bluetoothtransferservice.xml and
filemanagerservice.xml) must be copied to that folder.
\endlist
\section1 ServiceBrowser Class Definition
The ServiceBrowser class inherits from QWidget. It has several slots for reloading the lists in the three information panes, and for changing the default implementation for an interface.
\quotefromfile servicebrowser/servicebrowser.h
\skipto class ServiceBrowser
\printuntil private:
\dots
\skipto }
\printline }
\section1 ServiceBrowser Class Implementation
\quotefromfile servicebrowser/servicebrowser.cpp
\skipto ServiceBrowser::ServiceBrowser
\printuntil }
The constructor registers the "FileManagerService", "BluetoothTransferService" and "NotesManagerServices" services that are provided by the \l{File Manager Plugin Example}{filemanagerplugin} and \l {Bluetooth Transfer Plugin Example}{bluetoothtransferplugin} projects in the \c examples/ directory. It also calls \c reloadServicesList() to show these two newly registered services in the top-left pane.
\quotefromfile servicebrowser/servicebrowser.cpp
\skipto ServiceBrowser::reloadServicesList
\printuntil }
When the services list in the top-left pane needs to be refreshed, we call QServiceManager::findServices() to get a QStringList of all services that are currently registered with the service framework.
\quotefromfile servicebrowser/servicebrowser.cpp
\skipto ServiceBrowser::reloadInterfaceImplementationsList
\printuntil {
\skipto findInterfaces
\dots
\dots
\printuntil }
\dots
\skipto }
\printline }
To create the list of interface implementations in the bottom-left pane, we call QServiceManager::findInterfaces() to get a list of QServiceInterfaceDescriptor objects. If a particular service has been selected in the top-left pane, we call QServiceManager::findInterfaces() with the name of that service as the argument, so that it will only return the interface implementations provided by that service. Otherwise, it is called with no argument to retrieve a list of all implementations provided by all registered services.
The example maps each entry in the interface implementations list to its corresponding QServiceInterfaceDescriptor object using the QListWidgetItem::setData() method.
Note how we also call QServiceManager::defaultServiceInterface() to determine whether an interface implementation is the default for that interface.
\quotefromfile servicebrowser/servicebrowser.cpp
\skipto ServiceBrowser::reloadAttributesList
\printto attributesListWidget->clear()
\dots
The \c reloadAttributesList() method creates the list in the right-hand pane that shows the attributes of an interface implementation that can be invoked through the Qt meta-object system.
QServiceManager::loadInterface() is called to get an instance of the identified interface implementation. This method finds the corresponding service plugin and returns the QObject instance provided by the service plugin's QServicePluginInterface::createInstance() method.
\quotefromfile servicebrowser/servicebrowser.cpp
\skipto ServiceBrowser::reloadAttributesList
\skipto QMetaObject
\dots
\printto setDefaultInterfaceImplementation
Call QObject::metaObject() on the implementation instance to get a QMetaObject instance that reveals the dynamically invokable attributes for the instance. These attributes include properties, signals, slots, and methods marked with the Q_INVOKABLE macro. Call QMetaObject::method() to get information about a signal, slot or invokable method, and QMetaObject::property() to access a property of the instance.
When you know the name of the method you wish to invoke, call QMetaObject::invoke() or QMetaMethod::invoke() to invoke it dynamically. Similarly, QMetaProperty::read() and QMetaProperty::write() can be used to read and modify the value of a property.
\section2 Invoking attributes: an example
Here is an example of invoking attributes on an implementation, using the \l{File Manager Plugin Example}{FileManagerPlugin} that is shown in the Service Browser.
The \l{File Manager Plugin Example}{FileManagerPlugin} provides a service called "FileManagerService" in its \c filemanagerplugin.xml service definition. When FileManagerPlugin::createInstance() is called, if the com.nokia.qt.examples.FileStorage interface is requested, it returns an instance of the FileManagerStorage class. The FileManagerStorage class is defined like this:
\quotefromfile filemanagerplugin/filemanagerstorage.h
\skipto class FileManagerStorage
\printuntil };
So if, in the ServiceBrowser application, we select the com.nokia.qt.examples.FileStorage implementation provided by FileManagerService, the browser would display all the dynamically invokable attributes of the FileManagerStorage class:
\image servicebrowser-attributes.png
As you can see, the FileManagerStorage::workingDirectory property, the FileManagerStorage::copyFile() slot and the FileManagerStorage::workingDirectoryChanged() signal are all listed. (The destroyed(), deleteLater() and _q_reregisterTimers() attributes are inherited from the QObject parent.)
To invoke the \c copyFile() slot, for example:
\code
QObject *interfaceImpl = QServiceManager::loadInterface("com.nokia.qt.examples.FileStorage", 0, 0);
QMetaObject::invokeMethod(interfaceImpl, "copyFile",
Q_ARG(QString, "path/to/file.txt"),
Q_ARG(QString, "new/path/to/file.txt"));
\endcode
Of course, the QServiceManager::loadInterface() call here assumes the FileManagerStorage implementation is the default for the com.nokia.qt.examples.FileStorage interface. Otherwise, it would have to pass a QServiceInterfaceDescriptor object to QServiceManager::loadInterface() instead of just the interface name to ensure the correct implementation is loaded.
*/
|
