QMqtt Namespace

Contains miscellaneous identifiers used throughout the Qt MQTT module. More...

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

This namespace was introduced in Qt 5.12.


enum class MessageStatus { Unknown, Published, Acknowledged, Received, Released, Completed }
enum class PayloadFormatIndicator { Unspecified, UTF8Encoded }
enum class ReasonCode { Success, SubscriptionQoSLevel0, SubscriptionQoSLevel1, SubscriptionQoSLevel2, NoMatchingSubscriber, …, WildCardSubscriptionsNotSupported }

Detailed Description

Type Documentation

enum class QMqtt::MessageStatus

This enum type specifies the available states of a message. Depending on the QoS and role of the client, different message statuses are expected.

QMqtt::MessageStatus::Unknown0The message status is unknown.
QMqtt::MessageStatus::Published1The client received a message for one of its subscriptions. This applies to QoS levels 1 and 2.
QMqtt::MessageStatus::Acknowledged2A message has been acknowledged. This applies to QoS 1 and states that the message handling has been finished from the client side.
QMqtt::MessageStatus::Received3A message has been received. This applies to QoS 2.
QMqtt::MessageStatus::Released4A message has been released. This applies to QoS 2. For a publisher the message handling has been finished.
QMqtt::MessageStatus::Completed5A message has been completed. This applies to QoS 2 and states that the message handling has been finished from the client side.

This enum was introduced or modified in Qt 5.12.

enum class QMqtt::PayloadFormatIndicator

The payload format provides information on the content of a message. This can help other clients to handle the message faster.

QMqtt::PayloadFormatIndicator::Unspecified0The format is not specified.
QMqtt::PayloadFormatIndicator::UTF8Encoded1The payload of the message is formatted as UTF-8 Encoded Character Data.

This enum was introduced or modified in Qt 5.12.

enum class QMqtt::ReasonCode

This enum type specifies the available error codes.

QMqtt::ReasonCode::Success0The specified action has succeeded.
QMqtt::ReasonCode::SubscriptionQoSLevel00A subscription with QoS level 0 has been created.
QMqtt::ReasonCode::SubscriptionQoSLevel10x01A subscription with QoS level 1 has been created.
QMqtt::ReasonCode::SubscriptionQoSLevel20x02A subscription with QoS level 2 has been created.
QMqtt::ReasonCode::NoMatchingSubscriber0x10The message has been accepted by the server, but there are no subscribers to receive this message. A broker may send this reason code instead of Success.
QMqtt::ReasonCode::NoSubscriptionExisted (since Qt 5.15)0x11No matching Topic Filter is being used by the Client.
QMqtt::ReasonCode::ContinueAuthentication (since Qt 5.15)0x18Continue the authentication with another step.
QMqtt::ReasonCode::ReAuthenticate (since Qt 5.15)0x19Initiate a re-authentication.
QMqtt::ReasonCode::UnspecifiedError0x80An unspecified error occurred.
QMqtt::ReasonCode::MalformedPacket0x81The packet sent to the server is invalid.
QMqtt::ReasonCode::ProtocolError0x82A protocol error has occurred. In most cases, this will cause the server to disconnect the client.
QMqtt::ReasonCode::ImplementationSpecificError0x83The packet is valid, but the recipient rejects it.
QMqtt::ReasonCode::UnsupportedProtocolVersion0x84The requested protocol version is not supported by the server.
QMqtt::ReasonCode::InvalidClientId0x85The client ID is invalid.
QMqtt::ReasonCode::InvalidUserNameOrPassword0x86The username or password specified is invalid.
QMqtt::ReasonCode::NotAuthorized0x87The client is not authorized for the specified action.
QMqtt::ReasonCode::ServerNotAvailable0x88The server to connect to is not available.
QMqtt::ReasonCode::ServerBusy0x89The server to connect to is not available. The client is asked to try at a later time.
QMqtt::ReasonCode::ClientBanned0x8AThe client has been banned from the server.
QMqtt::ReasonCode::InvalidAuthenticationMethod0x8CThe authentication method specified is invalid.
QMqtt::ReasonCode::InvalidTopicFilter0x8FThe topic filter specified is invalid.
QMqtt::ReasonCode::InvalidTopicName0x90The topic name specified is invalid.
QMqtt::ReasonCode::MessageIdInUse0x91The message ID used in the previous packet is already in use.
QMqtt::ReasonCode::MessageIdNotFound0x92The message ID used in the previous packet has not been found.
QMqtt::ReasonCode::PacketTooLarge0x95The packet received is too large. See also QMqttServerConnectionProperties::maximumPacketSize().
QMqtt::ReasonCode::QuotaExceeded0x97An administratively imposed limit has been exceeded.
QMqtt::ReasonCode::InvalidPayloadFormat0x99The payload format is invalid. See also QMqttPublishProperties::payloadFormatIndicator().
QMqtt::ReasonCode::RetainNotSupported0x9AThe server does not support retained messages. See also QMqttServerConnectionProperties::retainAvailable().
QMqtt::ReasonCode::QoSNotSupported0x9BThe QoS level requested is not supported. See also QMqttServerConnectionProperties::maximumQoS().
QMqtt::ReasonCode::UseAnotherServer0x9CThe server the client tries to connect to is not available. See also QMqttServerConnectionProperties::serverReference().
QMqtt::ReasonCode::ServerMoved0x9DThe server the client tries to connect to has moved to a new address. See also QMqttServerConnectionProperties::serverReference().
QMqtt::ReasonCode::SharedSubscriptionsNotSupported0x9EShared subscriptions are not supported. See also QMqttServerConnectionProperties::sharedSubscriptionSupported().
QMqtt::ReasonCode::ExceededConnectionRate0x9FThe connection rate limit has been exceeded.
QMqtt::ReasonCode::SubscriptionIdsNotSupported0xA1Subscription IDs are not supported. See also QMqttServerConnectionProperties::subscriptionIdentifierSupported().
QMqtt::ReasonCode::WildCardSubscriptionsNotSupported0xA2Subscriptions using wildcards are not supported by the server. See also QMqttServerConnectionProperties::wildcardSupported().

Not all values are available in every use case. Especially, some servers will reject a reason code not suited for a specific command. See below table to highlight expected reason codes for specific actions.

Reason CodeConnect PropertiesSubscription PropertiesMessage Properties

This enum was introduced or modified in Qt 5.12.

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