// Copyright (C) 2023 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only

/*!
    \example sensors
    \ingroup qtprotobuf-examples
    \meta tag {network,protobuf,serialization,udp}
    \examplecategory {Networking}
    \title Sensors

    \brief The Sensors example shows how two applications can communicate by
    sending protobuf messages using UDP sockets.

    The Sensors example consists of the following components:
    \list
    \li \c protobuf_sensors library that you generate from the protobuf schema
        using the \l qt_add_protobuf call.
    \li \c protobuf_sensor_emulator application that emulates simple sensor
        behavior.
    \li \c protobuf_sensors_client application that displays the sensor data
        from the UDP socket.
    \endlist

    The client application binds on the \c localhost UDP port \c 65500 and
    waits for data from the emulator application.
    \image client.webp

    Use the emulator application to change the values of sensor data and send
    the data to the client's UDP port.
    \image emulator.webp {Screenshot showing an emulator console application
           to send coordinates, weather temperature, and a warning message}

    The applications use the generated messages from the \c protobuf_sensors
    library to communicate. The library is generated from the protobuf schema
    described in .proto files.
    \snippet sensors/CMakeLists.txt 0
    The first file describes the Type-Length-Value message, that wraps the
    sensor data:
    \snippet sensors/tlv.proto 0
    The second .proto file contains a description of the sensor messages:
    \snippet sensors/sensors.proto 0

    Messages are serialized using \l QProtobufSerializer that you instantiate in
    the client:
    \code
    class SensorClient : public QObject
    {
        Q_OBJECT
    ...
    private:
        QUdpSocket m_client;
        QProtobufSerializer m_serializer;
    };
    \endcode
    And the emulator:
    \code
    class SensorEmulator : public QObject
    {
        Q_OBJECT
    ...
        QUdpSocket m_socket;
        QProtobufSerializer m_serializer;
    };
    \endcode

    After you click the \uicontrol Send button in the emulator application, the
    data from \l QLineEdit fields is converted from string format to the message
    field-specific format, for example, double for the fields of the Coordinates
    message:
    \snippet sensors/emulator/emulatorconsole.cpp 0
    Then the message with all the fields is serialized and wrapped with the
    Type-Length-Value message:
    \snippet sensors/emulator/sensoremulator.cpp 0

    The client applies the reverse operations on the received datagrams. First
    the Type-Length-Value message is deserialized from the datagram data:
    \snippet sensors/client/sensorclient.cpp 0

    Then the Type-Length-Value message is deserialized into the sensor message:
    \snippet sensors/client/sensorclient.cpp 1
    Finally, it is converted and displayed to the user:
    \snippet sensors/client/clientconsole.cpp 0

    \note Before running the example, make sure that your operating system
    allows binding on UDP port \c 65500 and sending the data over UDP.
*/