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// 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
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.
*/
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