Library_Project/demo/mqtt/qmqtt-API.md

qmqtt API

enum ClientError
{
    UnknownError = 0,
    SocketConnectionRefusedError,
    SocketRemoteHostClosedError,
    SocketHostNotFoundError,
    SocketAccessError, 
    SocketResourceError, 
    SocketTimeoutError, 
    SocketDatagramTooLargeError,
    SocketNetworkError, 
    SocketAddressInUseError, 
    SocketAddressNotAvailableError,
    SocketUnsupportedSocketOperationError,
    SocketUnfinishedSocketOperationError,
    SocketProxyAuthenticationRequiredError,
    SocketSslHandshakeFailedError,
    SocketProxyConnectionRefusedError,
    SocketProxyConnectionClosedError,
    SocketProxyConnectionTimeoutError,
    SocketProxyNotFoundError,
    SocketProxyProtocolError,
    SocketOperationError,
    SocketSslInternalError,
    SocketSslInvalidUserDataError,
    SocketTemporaryError,
    MqttUnacceptableProtocolVersionError=1<<16,
    MqttIdentifierRejectedError,
    MqttServerUnavailableError,
    MqttBadUserNameOrPasswordError,
    MqttNotAuthorizedError,
    MqttNoPingResponse 
}

This enum describes the client errors that can occur.

Constant	Value	Description
UnknownError	0	An unidentified error occurred.
SocketConnectionRefusedError	1	The connection was refused by the peer (or timed out).
SocketRemoteHostClosedError	2	The remote host closed the connection. Note that the client socket (i.e., this socket) will be closed after the remote close notification has been sent.
SocketHostNotFoundError	3	The host address was not found.
SocketAccessError	4	The socket operation failed because the application lacked the required privileges.
SocketResourceError	5	The local system ran out of resources (e.g., too many sockets).
SocketTimeoutError	6	The socket operation timed out.
SocketDatagramTooLargeError	7	The datagram was larger than the operating system's limit (which can be as low as 8192 bytes).
SocketNetworkError	8	An error occurred with the network (e.g., the network cable was accidentally plugged out).
SocketAddressInUseError	9	The address is already in use and was set to be exclusive.
SocketAddressNotAvailableError	10	The address does not belong to the host.
SocketUnsupportedSocketOperationError	11	The requested socket operation is not supported by the local operating system (e.g., lack of IPv6 support).
SocketUnfinishedSocketOperationError	12	Used by QAbstractSocketEngine only, The last operation attempted has not finished yet (still in progress in the background).
SocketProxyAuthenticationRequiredError	13	The socket is using a proxy, and the proxy requires authentication.
SocketSslHandshakeFailedError	14	The SSL/TLS handshake failed, so the connection was closed.
SocketProxyConnectionRefusedError	15	Could not contact the proxy server because the connection to that server was denied
SocketProxyConnectionClosedError	16	The connection to the proxy server was closed unexpectedly (before the connection to the final peer was established)
SocketProxyConnectionTimeoutError	17	The connection to the proxy server timed out or the proxy server stopped responding in the authentication phase.
SocketProxyNotFoundError	18	The proxy address set with (or the application proxy) was not found.
SocketProxyProtocolError	19	The connection negotiation with the proxy server failed, because the response from the proxy server could not be understood.
SocketOperationError	20	An operation was attempted while the socket was in a state that did not permit it.
SocketSslInternalError	21	The SSL library being used reported an internal error. This is probably the result of a bad installation or misconfiguration of the library.
SocketSslInvalidUserDataError	22	Invalid data (certificate, key, cypher, etc.) was provided and its use resulted in an error in the SSL library.
SocketTemporaryError	23	A temporary error occurred (e.g., operation would block and socket is non-blocking).
MqttUnacceptableProtocolVersionError	65536	The Server does not support the level of the MQTT protocol requested by the Client.
MqttIdentifierRejectedError	65537	The Client identifier is correct UTF-8 but not allowed by the Server.
MqttServerUnavailableError	65538	The Network Connection has been made but the MQTT service is unavailable.
MqttBadUserNameOrPasswordError	65539	The data in the user name or password is malformed.
MqttNotAuthorizedError	65540	The Client is not authorized to connect.
MqttNoPingResponse	65541	Ping response timeout.

Client Class

---

Public signals

	Signals	Brief
void	connected()	Receive when connected.
void	disconnected()	Receive when disconnected.
void	error(const QMQTT::ClientError error)	Receive when client error occured.
void	subscribed(const QString& topic, const quint8 qos)	Receive when subscribe is succeeded.
void	unsubscribed(const QString& topic)	Receive when unsubscribe is succeeded.
void	published(const quint16 msgid, const quint8 qos)	Receive when publish is succeeded.
void	pingresp()	Receive when ping response is received.
void	received(const QMQTT::Message& message)	Receive when message is received.

Public Functions

Return	Function members	Brief
Client	Client(const QHostAddress& host = QHostAddress::LocalHost, const quint16 port = 1883, QObject* parent = NULL);	Constructor client object.
void	setHost(const QHostAddress& host)	Set host address.
void	setHostName(const QString& hostName)	Set host name.
void	setPort(const quint16 port)	Set port.
void	setClientId(const QString& clientId)	Set client identify.
void	setUsername(const QString& username)	Set user name.
void	setPassword(const QByteArray& password)	Set password.
void	setVersion(const MQTTVersion version)	Set mqtt version.
void	setKeepAlive(const quint16 keepAlive)	Set keep alive interval.
void	setCleanSession(const bool cleanSession)	Set clean session option.
void	setAutoReconnect(const bool value)	Set auto reconnect.
void	setAutoReconnectInterval(const int autoReconnectInterval)	Set auto reconnect interval.
void	setWillTopic(const QString& willTopic)	Set will topic.
void	setWillQos(const quint8 willQos)	Set will qos level.
void	setWillRetain(const bool willRetain)	Set will retain.
void	setWillMessage(const QByteArray& willMessage)	Set will message.
void	connectToHost()	Connect to host.
void	disconnectFromHost()	Disconnect from host.
void	subscribe(const QString& topic, const quint8 qos = 0)	Subscribe topic with certain qos.
void	unsubscribe(const QString& topic)	Unsubscribe a topic.
quint16	publish(const QMQTT::Message& message)	Publish a Message.

Client

Client(const QHostAddress& host = QHostAddress::LocalHost,
       const quint16 port = 1883,
       QObject* parent = NULL);

Client constructor. Parameters

• host: Host ip.
• port: Host port.
• parent: QObject.

Returns

• Client object.

setHost

void setHost(const QHostAddress& host) Set host ip address. For example:

QMQTT::Client client;
const QHostAddress EXAMPLE_HOST = QHostAddress("34.211.84.46");
client.setHost(HOST);

Parameters

• host: Host ip.

Returns

setHostName

setHostName(const QString& hostName) Set host name. For example:

QMQTT::Client client;
client.setHostName("broker.emqx.io");

Parameters

• hostName: Host name.

Returns

setPort

setPort(const quint16 port) Set port num. For example:

QMQTT::Client client;
client.setPort(1883);

Parameters

• port: Port num.

Returns

setClientId

setClientId(const QString& clientId) Set client identify. For example:

QMQTT::Client client;
client.setClientId("clientid");

Parameters

• clientId: Client identify.

Returns

setUsername

void setUsername(const QString& username) Set username. For example:

QMQTT::Client client;
client.setUsername("username");

Parameters

• username: Username.

Returns

setVersion

void setVersion(const MQTTVersion version) Set mqtt version. For example:

QMQTT::Client client;
client.setVersion(QMQTT::V3_1_1);

Parameters

• version: Mqtt version. For now only support 3.1.0 and 3.1.1.

Returns

setKeepAlive

void setKeepAlive(const quint16 keepAlive); Set Keep alive interval. For example:

QMQTT::Client client;
client.setKeepAlive(100);

Parameters

• keepAlive: Keep alive interval, default is 300.

Returns

setCleanSession

void setCleanSession(const bool cleanSession) Set clean session flag. For example:

QMQTT::Client client;
client.setCleanSession(true);

Parameters

• cleanSession: Set clean session, if true clean session, false keep session, default is false.

Returns

setAutoReconnect

void setAutoReconnect(const bool value) Set auto reconnect. For example:

QMQTT::Client client;
client.setAutoReconnect(true);

Parameters

• value: Auto reconnect or not, true auto reconnect, false do not reconnect.

Returns

setAutoReconnectInterval

void setAutoReconnectInterval(const int autoReconnectInterval) Set auto reconnect interval. For example:

QMQTT::Client client;
client.setAutoReconnectInterval(10);

Parameters

• autoReconnectInterval: Auto reconnect interval (second).

Returns

setWillTopic

void setWillTopic(const QString& willTopic) Set will topic info. For example:

QMQTT::Client client;
client.setWillTopic("will topic");

Parameters

• willTopic: Will topic.

Returns

setWillQos

void setWillQos(const quint8 willQos) Set will qos level. For example:

QMQTT::Client client;
client.setWillQos(1);

Parameters

• willQos: Will qos level.

Returns

setWillRetain

void setWillRetain(const bool willRetain) Set will retain flag. For example:

QMQTT::Client client;
client.setWillRetain(true);

Parameters

• willRetain: Will retain flag.

Returns

setWillMessage

void setWillMessage(const QByteArray& willMessage) Set will message. For example:

QMQTT::Client client;
QByteArray ba("Hello");
client.setWillMessage(ba);

Parameters

• willMessage: Will message.

Returns

connectToHost

void connectToHost() Connect to host. For example:

QMQTT::Client client;
client.connectToHost();

Parameters

Returns

disconnectFromHost

void disconnectFromHost() Disconnect from host. For example:

QMQTT::Client client;
client.disconnectFromHost();

Parameters

Returns

subscribe

void subscribe(const QString& topic, const quint8 qos = 0) Subscribe a topic with a certain qos level.

QMQTT::Client client;
client.subscribe("topic", 1);

Parameters

• topic: subscribe topic.
• qos: subscribe topic qos level, default is 0.

Returns

unsubscribe

void unsubscribe(const QString& topic) Unsubscribe a topic.

QMQTT::Client client;
client.unsubscribe("topic");

Parameters

• topic: unsubscribe topic.

Returns

publish

quint16 publish(const QMQTT::Message& message) Publish a Message.

QMQTT::Client client;
QMQTT::Message message(1, "topic", QString("Hello").toUtf8());
message.setQos(2);
client.publish(message);

Parameters

• message: Message info see below.

Returns

Message Class

---

Public Functions

Return	Function members	Brief
Message	Message()	Construct Message object
Message	Message(const quint16 id, const QString &topic, const QByteArray &payload, const quint8 qos = 0, const bool retain = false, const bool dup = false)	Construct Message object
Message	Message(const Message &other)	Construct Message object
Message	~Message()	Destructor Message object
quint16	id() const	Get id
void	setId(const quint16 id)	Set id
quint8	qos() const	Get qos
void	setQos(const quint8 qos)	Set Qos
bool	retain() const	Get retain
void	setRetain(const bool retain)	Set retain
bool	dup() const	Get dup
void	setDup(const bool dup)	Set Dup
QString	topic() const	Get topic
void	setTopic(const QString &topic)	Set topic
QByteArray	payload() const	Get payload
void	setPayload(const QByteArray &payload)	Set payload

Message

Message()
Message(const quint16 id, const QString &topic, const QByteArray &payload,const quint8 qos = 0, const bool retain = false, const bool dup = false)
Message(const Message &other)

id

quint16 id() const Get id from Message. Parameters

Returns

• Message identify.

setId

void setId(const quint16 id) Set id to Message. Parameters

• id: Message identify

Returns

qos

quint8 qos() const Get qos level from Message. Parameters

Returns

• Message qos level.

setQos

void setQos(const quint8 qos) Set Message Qos level. Parameters

• qos: Message qos level.

Returns

retain

bool retain() const Get retain flag from Message. Parameters

Returns

• Had retain flag been set.

setRetain

void setRetain(const bool retain) Set retain flag to Message. Parameters

• retain: Set retain flag.

Returns

dup

bool dup() const Get dup flag from Message. Parameters

Returns

• Dup flag been se.

setDup

void setDup(const bool dup) Set dup flag for Message. Parameters

• dup: Dup flag.

Returns

topic

QString topic() const Get topic from Message. Parameters

Returns

• Get Message topic.

setTopic

void setTopic(const QString &topic) Set topic to Message. Parameters

• topic: Set Message topic.

Returns

payload

QByteArray payload() const Get payload form Message. Parameters

Returns

• Message payload.

setPayload

void setPayload(const QByteArray &payload) Set payload for Message. Parameters

• payload: SetMessage payload.

Returns