QMqttPublishProperties Class

The QMqttPublishProperties class represents configuration options for sending or receiving a message. More...

Header:	#include <QMqttPublishProperties>
qmake:	QT += mqtt
Since:	Qt 5.12

• List of all members, including inherited members

Public Types

enum	PublishPropertyDetail { None, PayloadFormatIndicator, MessageExpiryInterval, TopicAlias, ResponseTopic, …, ContentType }
flags	PublishPropertyDetails

Public Functions

QMqttPublishProperties::PublishPropertyDetails	availableProperties() const
QString	contentType() const
QByteArray	correlationData() const
quint32	messageExpiryInterval() const
QMqtt::PayloadFormatIndicator	payloadFormatIndicator() const
QString	responseTopic() const
void	setContentType(const QString &type)
void	setCorrelationData(const QByteArray &correlation)
void	setMessageExpiryInterval(quint32 interval)
void	setPayloadFormatIndicator(QMqtt::PayloadFormatIndicator indicator)
void	setResponseTopic(const QString &topic)
void	setSubscriptionIdentifiers(const QList<quint32> &ids)
void	setTopicAlias(quint16 alias)
void	setUserProperties(const QMqttUserProperties &properties)
QList<quint32>	subscriptionIdentifiers() const
quint16	topicAlias() const
QMqttUserProperties	userProperties() const

Detailed Description

Invoking QMqttClient::publish() to send a message to a broker can include QMqttPublishProperties to provide additional arguments on how the message should be treated on the broker.

Furthermore receiving a message by an instantiated subscription might contain publish properties which have been forwarded or adapted by the server.

Member Type Documentation

enum QMqttPublishProperties::PublishPropertyDetailflags QMqttPublishProperties::PublishPropertyDetails

This enum type specifies the available properties set by the server or the client when creating a message.

Constant	Value	Description
QMqttPublishProperties::None	0x00000000	No property has been specified.
QMqttPublishProperties::PayloadFormatIndicator	0x00000001	The type of content of the message.
QMqttPublishProperties::MessageExpiryInterval	0x00000002	The duration a message is valid.
QMqttPublishProperties::TopicAlias	0x00000004	The topic alias for this message.
QMqttPublishProperties::ResponseTopic	0x00000008	The topic the receipient should respond to.
QMqttPublishProperties::CorrelationData	0x00000010	An identifier of the response message.
QMqttPublishProperties::UserProperty	0x00000020	Additional properties set by the user.
QMqttPublishProperties::SubscriptionIdentifier	0x00000040	An identifier of subscriptions matching the publication.
QMqttPublishProperties::ContentType	0x00000080	A description of the content of the message.

The PublishPropertyDetails type is a typedef for QFlags<PublishPropertyDetail>. It stores an OR combination of PublishPropertyDetail values.

Member Function Documentation

QMqttPublishProperties::PublishPropertyDetails QMqttPublishProperties::availableProperties() const

Returns the available properties specified in this instance. When a message is created, it does not need to include all properties. This function serves as an indicator of those properties which have been explicitly set.

QString QMqttPublishProperties::contentType() const

Returns the content type of the message.

See also setContentType().

QByteArray QMqttPublishProperties::correlationData() const

Returns the correlation data.

See also setCorrelationData().

quint32 QMqttPublishProperties::messageExpiryInterval() const

Returns the message expiry interval. This value specifies the number of seconds a server is allowed to forward the message. If the interval expires, the server must delete the message and abort publishing it.

See also setMessageExpiryInterval().

QMqtt::PayloadFormatIndicator QMqttPublishProperties::payloadFormatIndicator() const

Returns the payload format indicator.

See also setPayloadFormatIndicator().

QString QMqttPublishProperties::responseTopic() const

Returns the response topic a user should use as a follow up to a request.

See also setResponseTopic().

void QMqttPublishProperties::setContentType(const QString &type)

Sets the content type of the message to type.

See also contentType().

void QMqttPublishProperties::setCorrelationData(const QByteArray &correlation)

Sets the correlation data to correlation.

See also correlationData().

void QMqttPublishProperties::setMessageExpiryInterval(quint32 interval)

Sets the message expiry interval to interval.

See also messageExpiryInterval().

void QMqttPublishProperties::setPayloadFormatIndicator(QMqtt::PayloadFormatIndicator indicator)

Sets the payload format indicator to indicator.

See also payloadFormatIndicator().

void QMqttPublishProperties::setResponseTopic(const QString &topic)

Sets the response topic to topic.

See also responseTopic().

void QMqttPublishProperties::setSubscriptionIdentifiers(const QList<quint32> &ids)

Sets the subscription identifiers to ids.

See also subscriptionIdentifiers().

void QMqttPublishProperties::setTopicAlias(quint16 alias)

Sets the topic alias for publishing a message to alias. A topic alias value must be greater than zero and less than the maximum topic alias specified by the server.

See also topicAlias() and QMqttServerConnectionProperties::maximumTopicAlias().

void QMqttPublishProperties::setUserProperties(const QMqttUserProperties &properties)

Sets the user properties of a message to properties.

See also userProperties().

QList<quint32> QMqttPublishProperties::subscriptionIdentifiers() const

Returns the subscription identifiers of subscriptions matching the topic filter of the message.

See also setSubscriptionIdentifiers().

quint16 QMqttPublishProperties::topicAlias() const

Returns the topic alias used for publishing a message.

See also setTopicAlias().

QMqttUserProperties QMqttPublishProperties::userProperties() const

Returns the user properties of a message.

See also setUserProperties().