/****************************************************************************
**
** Copyright (C) 2017 The Qt Company Ltd and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:FDL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Free Documentation License Usage
** 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. Please review the following information to ensure
** the GNU Free Documentation License version 1.3 requirements
** will be met: https://www.gnu.org/licenses/fdl-1.3.html.
** $QT_END_LICENSE$
**
****************************************************************************/

/*!
    \group qml-serviceframework
    \title QML Service Framework Plugin
    QML Support for the QtMobility Project Service Framework API.
*/

/*!
    \page qml-serviceframework.html

    \title Service Framework QML Plugin

    \brief A QML plugin for the QtMobility Project Service Framework API.

    \section1 Overview

    The Service Framework API in the QtMobility Project gives developers a mechanism for
    discovering and instantiating arbitrary services. The QML Service Framework Plugin
    enables accessing services in a very easy and simple manner by allowing users to
    declare a service or find a list of services using QML.

    \section1 Elements
    The service framework QML plugin provides two elements that allow access to
    registered services via QML script. In general, the QML plugin can only discover
    and load pre-registered services and does not support any run-time registration or
    unregistration of services. The servicefw tool can be used to register services
    to the service framework system prior to running any QML script utilising this
    plugin. The two available elements are in the subsequent sections.

    \section2 Service
    The \l Service element provides QML with functionality reflecting the
    QServiceInterfaceDescriptor class which represents the details of a single service
    registered on the service framework system. This element also allows the service to
    be loaded so that it will return a QObject reference of the instantiated service
    object. If this element is used on its own and not in conjunction to the ServiceList
    element below, it will represent the default interface at the specified interface
    name, which is the most convenient use-case of the QML plugin. The code snippet below
    demonstrates a typical way to load an interface in QML.

    \qml
    import QtQuick 2.0
    import Qt.serviceframework 5.0

    // ...
    property variant myObject: 0

    Service {
        id: myService
        interfaceName: "com.nokia.qt.examples.ExampleService"

        Component.onCompleted: {
            myObject = myService.serviceObject;
        }
    }
    \endqml

    In the above code we use a variant to store the QObject reference provided by the
    Service::serviceObject. In this case it will be an instance of the default service
    found at the interface address "com.nokia.qt.examples.ExampleService". The code
    inside the QML component element is recommended so that the variable \e myObject
    holds a valid object instance which can be used throughout the entire QML script.

    This element also provides several readable properties about the service interface.
    A useful one is the Service::valid property which will help debug if the system
    has found a valid default interface descriptor at the specified interface name. The
    plugin also allows connecting to signals provided by the service. Here is a typical
    example of receiving service signals within QML for the above code.

    \qml
    Connections {
        target: myObject
        ignoreUnknownSignals: true

        onMySignal: {
            // do something
        }
    }
    \endqml

    Note the usage of the ignoreUnkownSignals attribute which is useful for ignoring
    uknown signals, especially in the case where Service::serviceObject has not been
    called yet or provides an invalid interface.

    Once a valid service instance has been obtained its methods and properties can be
    called and accessed as if it were normal QObject in QML. The service framework
    example \l{dialer}{Declarative Dialer Example} demonstrates the use
    of the QML plugin.

    \section2 ServiceList
    The \l ServiceList element provides QML with functionality reflecting the
    QServiceFilter class which provides a list of \l Service elements. A very specific
    service list element can be defined by using the following code.

    \qml
    ServiceList {
        id: myServiceList
        serviceName: "MyExampleService"
        interfaceName: "com.nokia.qt.examples.ExampleService"
        versionMatch: ServiceList.Exact
        majorVersion: 1
        minorVersion: 3
    }
    \endqml

    If the ServiceList::serviceName is not supplied the filter will search with a default
    empty string as the service name, meaning all interfaces will be returned regardless
    of the service name. Similarly if no ServiceList::versionMatch is provided the filter
    will search with a minimum version match rule.

    The actual QQmlListProperty of \l Service elements can be obtained by reading
    the ServiceList::services property which searches based on the filter values. This
    list model can then be used in a list view element.

    \qml
    ListView {
        id: myListView
        model: myServiceList.services
        delegate: myDelegate
        // ...
    }
    \endqml

    The service framework example \l{dialer}{Declarative Dialer Example} better
    demonstrates the use of ServiceList coupled with the \l Service element to search
    and select a service instance to implement the QML dialer application.

    \section1 Examples
    \list
        \li \l{dialer}{Declarative Serviceframework Dialer Example}
    \endlist

    \section1 QML Elements
    \annotatedlist qml-serviceframework
*/
