QMqttConnectionProperties Class | Qt MQTT 6.4.1

- Qt 6.4
- Qt MQTT
- C++ Classes
- QMqttConnectionProperties
- Qt 6.4.1 Reference Documentation

# QMqttConnectionProperties Class

The QMqttConnectionProperties class represents configuration options a QMqttClient can pass to the server when invoking QMqttClient::connectToHost(). More...

Header: | #include <QMqttConnectionProperties>
CMake: | find_package(Qt6 REQUIRED COMPONENTS Mqtt) target_link_libraries(mytarget PRIVATE Qt6::Mqtt)
qmake: | QT += mqtt
Since: | Qt 5.12
Inherited By: | QMqttServerConnectionProperties

- List of all members, including inherited members

## Public Functions

QByteArray | authenticationData() const
QString | authenticationMethod() const
quint32 | maximumPacketSize() const
quint16 | maximumReceive() const
quint16 | maximumTopicAlias() const
bool | requestProblemInformation() const
bool | requestResponseInformation() const
quint32 | sessionExpiryInterval() const
void | setAuthenticationData(const QByteArray &authData)
void | setAuthenticationMethod(const QString &authMethod)
void | setMaximumPacketSize(quint32 packetSize)
void | setMaximumReceive(quint16 maximumReceive)
void | setMaximumTopicAlias(quint16 alias)
void | setRequestProblemInformation(bool problem)
void | setRequestResponseInformation(bool response)
void | setSessionExpiryInterval(quint32 expiry)
void | setUserProperties(const QMqttUserProperties &properties)
QMqttUserProperties | userProperties() const

## Detailed Description

Note: Connection properties are part of the MQTT 5.0 specification and cannot be used when connecting with a lower protocol level. See QMqttClient::ProtocolVersion for more information.

## Member Function Documentation

### QByteArray QMqttConnectionProperties::authenticationData() const

Returns the authentication data.

See also setAuthenticationData().

### QString QMqttConnectionProperties::authenticationMethod() const

Returns the authentication method.

See also setAuthenticationMethod().

### quint32 QMqttConnectionProperties::maximumPacketSize() const

Returns the maximum packet size the client can receive.

See also setMaximumPacketSize().

### quint16 QMqttConnectionProperties::maximumReceive() const

Returns the maximum amount of QoS 1 and QoS 2 publications that the client (when obtained from QMqttClient::connectionProperties()) or the server (when obtained from QMqttClient::serverConnectionProperties()) is willing to process concurrently for this session.

See also setMaximumReceive().

### quint16 QMqttConnectionProperties::maximumTopicAlias() const

Returns the maximum topic alias ID the client can use.

See also setMaximumTopicAlias().

### bool QMqttConnectionProperties::requestProblemInformation() const

Returns whether the client should receive problem information.

See also setRequestProblemInformation().

### bool QMqttConnectionProperties::requestResponseInformation() const

Returns whether the client should receive response information.

See also setRequestResponseInformation().

### quint32 QMqttConnectionProperties::sessionExpiryInterval() const

Returns the session expiry interval.

See also setSessionExpiryInterval().

### void QMqttConnectionProperties::setAuthenticationData(const QByteArray &authData)

Sets the authentication data to authData.

Authentication data can only be used if an authentication method has been specified.

See also authenticationData() and authenticationMethod().

### void QMqttConnectionProperties::setAuthenticationMethod(const QString &authMethod)

Sets the authentication method to authMethod.

See also authenticationMethod() and authenticationData().

### void QMqttConnectionProperties::setMaximumPacketSize(quint32 packetSize)

Sets the maximum packet size to packetSize. The maximum packet size specifies the maximum size one packet can contain. This includes the packet header and its properties.

If no maximum packet size is specified, no limit is imposed beyond the limitations of the protocol itself.

See also maximumPacketSize().

### void QMqttConnectionProperties::setMaximumReceive(quint16 maximumReceive)

Sets the maximum amount of QoS 1 and QoS 2 publications that the client is willing to process concurrently for this session to maximumReceive.

A maximum receive value of 0 is not allowed.

See also maximumReceive().

### void QMqttConnectionProperties::setMaximumTopicAlias(quint16 alias)

Sets the maximum topic alias to alias. The maximum topic alias specifies the highest value that the client will accept from the server. The client uses this value to limit the number of topic aliases it is willing to hold for the connection.

The default value is 0. 0 indicates that the client does not accept any topic aliases on this connection.

See also maximumTopicAlias().

### void QMqttConnectionProperties::setRequestProblemInformation(bool problem)

Sets the request problem information to problem. A client uses this to request the server to return additional information in case of failure. Types of failure include connection and message management on the server side.

The default value is `false`, which indicates that the client must not receive any problem information for anything but connection management. The server still may send problem information for connection handling. If the value is `true`, the server may return problem information.

Problem information is available in user properties or reason strings of the property classes.

See also requestProblemInformation().

### void QMqttConnectionProperties::setRequestResponseInformation(bool response)

Sets the request response information to response. A client uses this to request the server to return response information after the connection request has been handled.

The default value is `false`, which indicates that the client must not return any response information. If the value is `true`, the server may return response information, but is not enforced to do so.

See also requestResponseInformation().

### void QMqttConnectionProperties::setSessionExpiryInterval(quint32 expiry)

Sets the session expiry interval to expiry. The session expiry interval specifies the number of seconds a server holds information on the client state after a connection has been closed.

The default value is 0, which specifies that the session is closed when the network connection ends. If the value is specified as maximum of quint32, then the session does not expire.

See also sessionExpiryInterval().

### void QMqttConnectionProperties::setUserProperties(const QMqttUserProperties &properties)

Sets the user properties of the connection to properties.

The default value is to not send any user information.

See also userProperties().

### QMqttUserProperties QMqttConnectionProperties::userProperties() const

Returns the user properties for the connection.

See also setUserProperties().