org.eclipse.paho.client.mqttv3

Class MqttAsyncClient

java.lang.Object

org.eclipse.paho.client.mqttv3.MqttAsyncClient

All Implemented Interfaces:

IMqttAsyncClient

public class MqttAsyncClient
extends java.lang.Object
implements IMqttAsyncClient

Lightweight client for talking to an MQTT server using non-blocking methods that allow an operation to run in the background.

This class implements the non-blocking IMqttAsyncClient client interface allowing applications to initiate MQTT actions and then carry on working while the MQTT action completes on a background thread. This implementation is compatible with all Java SE runtimes from 1.4.2 and up.

An application can connect to an MQTT server using:

• A plain TCP socket
• A secure SSL/TLS socket

To enable messages to be delivered even across network and client restarts messages need to be safely stored until the message has been delivered at the requested quality of service. A pluggable persistence mechanism is provided to store the messages.

By default MqttDefaultFilePersistence is used to store messages to a file. If persistence is set to null then messages are stored in memory and hence can be lost if the client, Java runtime or device shuts down.

If connecting with MqttConnectOptions.setCleanSession(boolean) set to true it is safe to use memory persistence as all state is cleared when a client disconnects. If connecting with cleanSession set to false in order to provide reliable message delivery then a persistent message store such as the default one should be used.

The message store interface is pluggable. Different stores can be used by implementing the MqttClientPersistence interface and passing it to the clients constructor.

See Also:

IMqttAsyncClient

Constructor Summary

Constructors

Constructor and Description
MqttAsyncClient(java.lang.String serverURI, java.lang.String clientId) Create an MqttAsyncClient that is used to communicate with an MQTT server.
MqttAsyncClient(java.lang.String serverURI, java.lang.String clientId, MqttClientPersistence persistence)
MqttAsyncClient(java.lang.String serverURI, java.lang.String clientId, MqttClientPersistence persistence, MqttPingSender pingSender) Create an MqttAsyncClient that is used to communicate with an MQTT server.

Method Summary

Modifier and Type	Method and Description
IMqttToken	checkPing(java.lang.Object userContext, IMqttActionListener callback)
void	close() Close the client Releases all resource associated with the client.
IMqttToken	connect() Connects to an MQTT server using the default options.
IMqttToken	connect(MqttConnectOptions options) Connects to an MQTT server using the provided connect options.
IMqttToken	connect(MqttConnectOptions options, java.lang.Object userContext, IMqttActionListener callback) Connects to an MQTT server using the specified options.
IMqttToken	connect(java.lang.Object userContext, IMqttActionListener callback) Connects to an MQTT server using the default options.
void	deleteBufferedMessage(int bufferIndex)
IMqttToken	disconnect() Disconnects from the server.
IMqttToken	disconnect(long quiesceTimeout) Disconnects from the server.
IMqttToken	disconnect(long quiesceTimeout, java.lang.Object userContext, IMqttActionListener callback) Disconnects from the server.
IMqttToken	disconnect(java.lang.Object userContext, IMqttActionListener callback) Disconnects from the server.
void	disconnectForcibly() Disconnects from the server forcibly to reset all the states.
void	disconnectForcibly(long disconnectTimeout) Disconnects from the server forcibly to reset all the states.
void	disconnectForcibly(long quiesceTimeout, long disconnectTimeout) Disconnects from the server forcibly to reset all the states.
static java.lang.String	generateClientId() Returns a randomly generated client identifier based on the the fixed prefix (paho) and the system time.
MqttMessage	getBufferedMessage(int bufferIndex)
int	getBufferedMessageCount()
java.lang.String	getClientId() Returns the client ID used by this client.
java.lang.String	getCurrentServerURI() Returns the currently connected Server URI Implemented due to: https://bugs.eclipse.org/bugs/show_bug.cgi?id=481097 Where getServerURI only returns the URI that was provided in MqttAsyncClient's constructor, getCurrentServerURI returns the URI of the Server that the client is currently connected to.
Debug	getDebug() Return a debug object that can be used to help solve problems.
IMqttDeliveryToken[]	getPendingDeliveryTokens() Returns the delivery tokens for any outstanding publish operations.
java.lang.String	getServerURI() Returns the address of the server used by this client.
boolean	isConnected() Determines if this client is currently connected to the server.
void	messageArrivedComplete(int messageId, int qos) Indicate that the application has completed processing the message with id messageId.
IMqttDeliveryToken	publish(java.lang.String topic, byte[] payload, int qos, boolean retained) Publishes a message to a topic on the server.
IMqttDeliveryToken	publish(java.lang.String topic, byte[] payload, int qos, boolean retained, java.lang.Object userContext, IMqttActionListener callback) Publishes a message to a topic on the server.
IMqttDeliveryToken	publish(java.lang.String topic, MqttMessage message) Publishes a message to a topic on the server.
IMqttDeliveryToken	publish(java.lang.String topic, MqttMessage message, java.lang.Object userContext, IMqttActionListener callback) Publishes a message to a topic on the server.
void	reconnect() User triggered attempt to reconnect
void	setBufferOpts(DisconnectedBufferOptions bufferOpts) Sets the DisconnectedBufferOptions for this client
void	setCallback(MqttCallback callback) Sets a callback listener to use for events that happen asynchronously.
void	setManualAcks(boolean manualAcks) If manualAcks is set to true, then on completion of the messageArrived callback the MQTT acknowledgements are not sent.
IMqttToken	subscribe(java.lang.String[] topicFilters, int[] qos) Subscribe to multiple topics, each of which may include wildcards.
IMqttToken	subscribe(java.lang.String[] topicFilters, int[] qos, IMqttMessageListener[] messageListeners) Subscribe to multiple topics, each of which may include wildcards.
IMqttToken	subscribe(java.lang.String[] topicFilters, int[] qos, java.lang.Object userContext, IMqttActionListener callback) Subscribes to multiple topics, each of which may include wildcards.
IMqttToken	subscribe(java.lang.String[] topicFilters, int[] qos, java.lang.Object userContext, IMqttActionListener callback, IMqttMessageListener[] messageListeners) Subscribe to multiple topics, each of which may include wildcards.
IMqttToken	subscribe(java.lang.String topicFilter, int qos) Subscribe to a topic, which may include wildcards.
IMqttToken	subscribe(java.lang.String topicFilter, int qos, IMqttMessageListener messageListener) Subscribe to a topic, which may include wildcards.
IMqttToken	subscribe(java.lang.String topicFilter, int qos, java.lang.Object userContext, IMqttActionListener callback) Subscribe to a topic, which may include wildcards.
IMqttToken	subscribe(java.lang.String topicFilter, int qos, java.lang.Object userContext, IMqttActionListener callback, IMqttMessageListener messageListener) Subscribe to a topic, which may include wildcards.
IMqttToken	unsubscribe(java.lang.String topicFilter) Requests the server unsubscribe the client from a topic.
IMqttToken	unsubscribe(java.lang.String[] topicFilters) Requests the server unsubscribe the client from one or more topics.
IMqttToken	unsubscribe(java.lang.String[] topicFilters, java.lang.Object userContext, IMqttActionListener callback) Requests the server unsubscribe the client from one or more topics.
IMqttToken	unsubscribe(java.lang.String topicFilter, java.lang.Object userContext, IMqttActionListener callback) Requests the server unsubscribe the client from a topics.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MqttAsyncClient

public MqttAsyncClient(java.lang.String serverURI,
                       java.lang.String clientId)
                throws MqttException

Create an MqttAsyncClient that is used to communicate with an MQTT server.

The address of a server can be specified on the constructor. Alternatively a list containing one or more servers can be specified using the setServerURIs method on MqttConnectOptions.

The serverURI parameter is typically used with the the clientId parameter to form a key. The key is used to store and reference messages while they are being delivered. Hence the serverURI specified on the constructor must still be specified even if a list of servers is specified on an MqttConnectOptions object. The serverURI on the constructor must remain the same across restarts of the client for delivery of messages to be maintained from a given client to a given server or set of servers.

The address of the server to connect to is specified as a URI. Two types of connection are supported tcp:// for a TCP connection and ssl:// for a TCP connection secured by SSL/TLS. For example:

• tcp://localhost:1883
• ssl://localhost:8883

If the port is not specified, it will default to 1883 for tcp://" URIs, and 8883 for ssl:// URIs.

A client identifier clientId must be specified and be less that 65535 characters. It must be unique across all clients connecting to the same server. The clientId is used by the server to store data related to the client, hence it is important that the clientId remain the same when connecting to a server if durable subscriptions or reliable messaging are required.

A convenience method is provided to generate a random client id that should satisfy this criteria - generateClientId(). As the client identifier is used by the server to identify a client when it reconnects, the client must use the same identifier between connections if durable subscriptions or reliable delivery of messages is required.

In Java SE, SSL can be configured in one of several ways, which the client will use in the following order:

• Supplying an SSLSocketFactory - applications can use MqttConnectOptions.setSocketFactory(SocketFactory) to supply a factory with the appropriate SSL settings.
• SSL Properties - applications can supply SSL settings as a simple Java Properties using MqttConnectOptions.setSSLProperties(Properties).
• Use JVM settings - There are a number of standard Java system properties that can be used to configure key and trust stores.

In Java ME, the platform settings are used for SSL connections.

An instance of the default persistence mechanism MqttDefaultFilePersistence is used by the client. To specify a different persistence mechanism or to turn off persistence, use the MqttAsyncClient(String, String, MqttClientPersistence) constructor.

Parameters:

serverURI - the address of the server to connect to, specified as a URI. Can be overridden using MqttConnectOptions.setServerURIs(String[])

clientId - a client identifier that is unique on the server being connected to

Throws:

java.lang.IllegalArgumentException - if the URI does not start with "tcp://", "ssl://" or "local://".

java.lang.IllegalArgumentException - if the clientId is null or is greater than 65535 characters in length

MqttException - if any other problem was encountered

MqttAsyncClient

public MqttAsyncClient(java.lang.String serverURI,
                       java.lang.String clientId,
                       MqttClientPersistence persistence)
                throws MqttException

Throws:

MqttException

MqttAsyncClient

public MqttAsyncClient(java.lang.String serverURI,
                       java.lang.String clientId,
                       MqttClientPersistence persistence,
                       MqttPingSender pingSender)
                throws MqttException

Create an MqttAsyncClient that is used to communicate with an MQTT server.

The address of a server can be specified on the constructor. Alternatively a list containing one or more servers can be specified using the setServerURIs method on MqttConnectOptions.

The serverURI parameter is typically used with the the clientId parameter to form a key. The key is used to store and reference messages while they are being delivered. Hence the serverURI specified on the constructor must still be specified even if a list of servers is specified on an MqttConnectOptions object. The serverURI on the constructor must remain the same across restarts of the client for delivery of messages to be maintained from a given client to a given server or set of servers.

The address of the server to connect to is specified as a URI. Two types of connection are supported tcp:// for a TCP connection and ssl:// for a TCP connection secured by SSL/TLS. For example:

• tcp://localhost:1883
• ssl://localhost:8883

If the port is not specified, it will default to 1883 for tcp://" URIs, and 8883 for ssl:// URIs.

A client identifier clientId must be specified and be less that 65535 characters. It must be unique across all clients connecting to the same server. The clientId is used by the server to store data related to the client, hence it is important that the clientId remain the same when connecting to a server if durable subscriptions or reliable messaging are required.

A convenience method is provided to generate a random client id that should satisfy this criteria - generateClientId(). As the client identifier is used by the server to identify a client when it reconnects, the client must use the same identifier between connections if durable subscriptions or reliable delivery of messages is required.

In Java SE, SSL can be configured in one of several ways, which the client will use in the following order:

• Supplying an SSLSocketFactory - applications can use MqttConnectOptions.setSocketFactory(SocketFactory) to supply a factory with the appropriate SSL settings.
• SSL Properties - applications can supply SSL settings as a simple Java Properties using MqttConnectOptions.setSSLProperties(Properties).
• Use JVM settings - There are a number of standard Java system properties that can be used to configure key and trust stores.

In Java ME, the platform settings are used for SSL connections.

A persistence mechanism is used to enable reliable messaging. For messages sent at qualities of service (QoS) 1 or 2 to be reliably delivered, messages must be stored (on both the client and server) until the delivery of the message is complete. If messages are not safely stored when being delivered then a failure in the client or server can result in lost messages. A pluggable persistence mechanism is supported via the MqttClientPersistence interface. An implementer of this interface that safely stores messages must be specified in order for delivery of messages to be reliable. In addition MqttConnectOptions.setCleanSession(boolean) must be set to false. In the event that only QoS 0 messages are sent or received or cleanSession is set to true then a safe store is not needed.

An implementation of file-based persistence is provided in class MqttDefaultFilePersistence which will work in all Java SE based systems. If no persistence is needed, the persistence parameter can be explicitly set to null.

Parameters:

serverURI - the address of the server to connect to, specified as a URI. Can be overridden using MqttConnectOptions.setServerURIs(String[])

clientId - a client identifier that is unique on the server being connected to

persistence - the persistence class to use to store in-flight message. If null then the default persistence mechanism is used

Throws:

java.lang.IllegalArgumentException - if the URI does not start with "tcp://", "ssl://" or "local://"

java.lang.IllegalArgumentException - if the clientId is null or is greater than 65535 characters in length

MqttException - if any other problem was encountered

Method Detail

connect

public IMqttToken connect(java.lang.Object userContext,
                          IMqttActionListener callback)
                   throws MqttException,
                          MqttSecurityException

Description copied from interface: IMqttAsyncClient

Connects to an MQTT server using the default options.

The default options are specified in MqttConnectOptions class.

Specified by:

connect in interface IMqttAsyncClient

Parameters:

userContext - optional object used to pass context to the callback. Use null if not required.

callback - optional listener that will be notified when the connect completes. Use null if not required.

Returns:

token used to track and wait for the connect to complete. The token will be passed to any callback that has been set.

Throws:

MqttSecurityException - for security related problems

MqttException - for non security related problems

See Also:

IMqttAsyncClient.connect(MqttConnectOptions, Object, IMqttActionListener)

connect

public IMqttToken connect()
                   throws MqttException,
                          MqttSecurityException

Description copied from interface: IMqttAsyncClient

Connects to an MQTT server using the default options.

The default options are specified in MqttConnectOptions class.

Specified by:

connect in interface IMqttAsyncClient

Returns:

token used to track and wait for the connect to complete. The token will be passed to the callback methods if a callback is set.

Throws:

MqttSecurityException - for security related problems

MqttException - for non security related problems

See Also:

IMqttAsyncClient.connect(MqttConnectOptions, Object, IMqttActionListener)

connect

public IMqttToken connect(MqttConnectOptions options)
                   throws MqttException,
                          MqttSecurityException

Description copied from interface: IMqttAsyncClient

Connects to an MQTT server using the provided connect options.

The connection will be established using the options specified in the MqttConnectOptions parameter.

Specified by:

connect in interface IMqttAsyncClient

Parameters:

options - a set of connection parameters that override the defaults.

Returns:

token used to track and wait for the connect to complete. The token will be passed to any callback that has been set.

Throws:

MqttSecurityException - for security related problems

MqttException - for non security related problems

See Also:

IMqttAsyncClient.connect(MqttConnectOptions, Object, IMqttActionListener)

connect

public IMqttToken connect(MqttConnectOptions options,
                          java.lang.Object userContext,
                          IMqttActionListener callback)
                   throws MqttException,
                          MqttSecurityException

Description copied from interface: IMqttAsyncClient

Connects to an MQTT server using the specified options.

The server to connect to is specified on the constructor. It is recommended to call IMqttAsyncClient.setCallback(MqttCallback) prior to connecting in order that messages destined for the client can be accepted as soon as the client is connected.

The method returns control before the connect completes. Completion can be tracked by:

• Waiting on the returned token IMqttToken.waitForCompletion() or
• Passing in a callback IMqttActionListener

Specified by:

connect in interface IMqttAsyncClient

Parameters:

options - a set of connection parameters that override the defaults.

userContext - optional object for used to pass context to the callback. Use null if not required.

callback - optional listener that will be notified when the connect completes. Use null if not required.

Returns:

token used to track and wait for the connect to complete. The token will be passed to any callback that has been set.

Throws:

MqttSecurityException - for security related problems

MqttException - for non security related problems including communication errors

disconnect

public IMqttToken disconnect(java.lang.Object userContext,
                             IMqttActionListener callback)
                      throws MqttException

Description copied from interface: IMqttAsyncClient

Disconnects from the server.

An attempt is made to quiesce the client allowing outstanding work to complete before disconnecting. It will wait for a maximum of 30 seconds for work to quiesce before disconnecting. This method must not be called from inside MqttCallback methods.

Specified by:

disconnect in interface IMqttAsyncClient

Parameters:

userContext - optional object used to pass context to the callback. Use null if not required.

callback - optional listener that will be notified when the disconnect completes. Use null if not required.

Returns:

token used to track and wait for the disconnect to complete. The token will be passed to any callback that has been set.

Throws:

MqttException - for problems encountered while disconnecting

See Also:

IMqttAsyncClient.disconnect(long, Object, IMqttActionListener)

disconnect

public IMqttToken disconnect()
                      throws MqttException

Description copied from interface: IMqttAsyncClient

Disconnects from the server.

An attempt is made to quiesce the client allowing outstanding work to complete before disconnecting. It will wait for a maximum of 30 seconds for work to quiesce before disconnecting. This method must not be called from inside MqttCallback methods.

Specified by:

disconnect in interface IMqttAsyncClient

Returns:

token used to track and wait for disconnect to complete. The token will be passed to any callback that has been set.

Throws:

MqttException - for problems encountered while disconnecting

See Also:

IMqttAsyncClient.disconnect(long, Object, IMqttActionListener)

disconnect

public IMqttToken disconnect(long quiesceTimeout)
                      throws MqttException

Description copied from interface: IMqttAsyncClient

Disconnects from the server.

An attempt is made to quiesce the client allowing outstanding work to complete before disconnecting. It will wait for a maximum of the specified quiesce time for work to complete before disconnecting. This method must not be called from inside MqttCallback methods.

Specified by:

disconnect in interface IMqttAsyncClient

Parameters:

quiesceTimeout - the amount of time in milliseconds to allow for existing work to finish before disconnecting. A value of zero or less means the client will not quiesce.

Returns:

token used to track and wait for disconnect to complete. The token will be passed to the callback methods if a callback is set.

Throws:

MqttException - for problems encountered while disconnecting

See Also:

IMqttAsyncClient.disconnect(long, Object, IMqttActionListener)

disconnect

public IMqttToken disconnect(long quiesceTimeout,
                             java.lang.Object userContext,
                             IMqttActionListener callback)
                      throws MqttException

Description copied from interface: IMqttAsyncClient

Disconnects from the server.

The client will wait for MqttCallback methods to complete. It will then wait for up to the quiesce timeout to allow for work which has already been initiated to complete. For instance when a QoS 2 message has started flowing to the server but the QoS 2 flow has not completed.It prevents new messages being accepted and does not send any messages that have been accepted but not yet started delivery across the network to the server. When work has completed or after the quiesce timeout, the client will disconnect from the server. If the cleanSession flag was set to false and is set to false the next time a connection is made QoS 1 and 2 messages that were not previously delivered will be delivered.

This method must not be called from inside MqttCallback methods.

The method returns control before the disconnect completes. Completion can be tracked by:

• Waiting on the returned token IMqttToken.waitForCompletion() or
• Passing in a callback IMqttActionListener

Specified by:

disconnect in interface IMqttAsyncClient

Parameters:

quiesceTimeout - the amount of time in milliseconds to allow for existing work to finish before disconnecting. A value of zero or less means the client will not quiesce.

userContext - optional object used to pass context to the callback. Use null if not required.

callback - optional listener that will be notified when the disconnect completes. Use null if not required.

Returns:

token used to track and wait for the connect to complete. The token will be passed to any callback that has been set.

Throws:

MqttException - for problems encountered while disconnecting

disconnectForcibly

public void disconnectForcibly()
                        throws MqttException

Description copied from interface: IMqttAsyncClient

Disconnects from the server forcibly to reset all the states. Could be useful when disconnect attempt failed.

Because the client is able to establish the TCP/IP connection to a none MQTT server and it will certainly fail to send the disconnect packet. It will wait for a maximum of 30 seconds for work to quiesce before disconnecting and wait for a maximum of 10 seconds for sending the disconnect packet to server.

Specified by:

disconnectForcibly in interface IMqttAsyncClient

Throws:

MqttException - if any unexpected error

disconnectForcibly

public void disconnectForcibly(long disconnectTimeout)
                        throws MqttException

Description copied from interface: IMqttAsyncClient

Disconnects from the server forcibly to reset all the states. Could be useful when disconnect attempt failed.

Because the client is able to establish the TCP/IP connection to a none MQTT server and it will certainly fail to send the disconnect packet. It will wait for a maximum of 30 seconds for work to quiesce before disconnecting.

Specified by:

disconnectForcibly in interface IMqttAsyncClient

Parameters:

disconnectTimeout - the amount of time in milliseconds to allow send disconnect packet to server.

Throws:

MqttException - if any unexpected error

disconnectForcibly

public void disconnectForcibly(long quiesceTimeout,
                               long disconnectTimeout)
                        throws MqttException

Description copied from interface: IMqttAsyncClient

Disconnects from the server forcibly to reset all the states. Could be useful when disconnect attempt failed.

Because the client is able to establish the TCP/IP connection to a none MQTT server and it will certainly fail to send the disconnect packet.

Specified by:

disconnectForcibly in interface IMqttAsyncClient

Parameters:

quiesceTimeout - the amount of time in milliseconds to allow for existing work to finish before disconnecting. A value of zero or less means the client will not quiesce.

disconnectTimeout - the amount of time in milliseconds to allow send disconnect packet to server.

Throws:

MqttException - if any unexpected error

isConnected

public boolean isConnected()

Description copied from interface: IMqttAsyncClient

Determines if this client is currently connected to the server.

Specified by:

isConnected in interface IMqttAsyncClient

Returns:

true if connected, false otherwise.

getClientId

public java.lang.String getClientId()

Description copied from interface: IMqttAsyncClient

Returns the client ID used by this client.

All clients connected to the same server or server farm must have a unique ID.

Specified by:

getClientId in interface IMqttAsyncClient

Returns:

the client ID used by this client.

getServerURI

public java.lang.String getServerURI()

Description copied from interface: IMqttAsyncClient

Returns the address of the server used by this client.

The format of the returned String is the same as that used on the constructor.

Specified by:

getServerURI in interface IMqttAsyncClient

Returns:

the server's address, as a URI String.

See Also:

MqttAsyncClient(String, String)

getCurrentServerURI

public java.lang.String getCurrentServerURI()

Returns the currently connected Server URI Implemented due to: https://bugs.eclipse.org/bugs/show_bug.cgi?id=481097 Where getServerURI only returns the URI that was provided in MqttAsyncClient's constructor, getCurrentServerURI returns the URI of the Server that the client is currently connected to. This would be different in scenarios where multiple server URIs have been provided to the MqttConnectOptions.

Returns:

the currently connected server URI

checkPing

public IMqttToken checkPing(java.lang.Object userContext,
                            IMqttActionListener callback)
                     throws MqttException

Throws:

MqttException

subscribe

public IMqttToken subscribe(java.lang.String topicFilter,
                            int qos,
                            java.lang.Object userContext,
                            IMqttActionListener callback)
                     throws MqttException

Description copied from interface: IMqttAsyncClient

Subscribe to a topic, which may include wildcards.

Specified by:

subscribe in interface IMqttAsyncClient

Parameters:

topicFilter - the topic to subscribe to, which can include wildcards.

qos - the maximum quality of service at which to subscribe. Messages published at a lower quality of service will be received at the published QoS. Messages published at a higher quality of service will be received using the QoS specified on the subscribe.

userContext - optional object used to pass context to the callback. Use null if not required.

callback - optional listener that will be notified when subscribe has completed

Returns:

token used to track and wait for the subscribe to complete. The token will be passed to callback methods if set.

Throws:

MqttException - if there was an error registering the subscription.

See Also:

IMqttAsyncClient.subscribe(String[], int[], Object, IMqttActionListener)

subscribe

public IMqttToken subscribe(java.lang.String topicFilter,
                            int qos)
                     throws MqttException

Description copied from interface: IMqttAsyncClient

Subscribe to a topic, which may include wildcards.

Specified by:

subscribe in interface IMqttAsyncClient

Parameters:

topicFilter - the topic to subscribe to, which can include wildcards.

qos - the maximum quality of service at which to subscribe. Messages published at a lower quality of service will be received at the published QoS. Messages published at a higher quality of service will be received using the QoS specified on the subscribe.

Returns:

token used to track and wait for the subscribe to complete. The token will be passed to callback methods if set.

Throws:

MqttException - if there was an error registering the subscription.

See Also:

IMqttAsyncClient.subscribe(String[], int[], Object, IMqttActionListener)

subscribe

public IMqttToken subscribe(java.lang.String[] topicFilters,
                            int[] qos)
                     throws MqttException

Description copied from interface: IMqttAsyncClient

Subscribe to multiple topics, each of which may include wildcards.

Provides an optimized way to subscribe to multiple topics compared to subscribing to each one individually.

Specified by:

subscribe in interface IMqttAsyncClient

Parameters:

topicFilters - one or more topics to subscribe to, which can include wildcards

qos - the maximum quality of service at which to subscribe. Messages published at a lower quality of service will be received at the published QoS. Messages published at a higher quality of service will be received using the QoS specified on the subscribe.

Returns:

token used to track and wait for the subscribe to complete. The token will be passed to callback methods if set.

Throws:

MqttException - if there was an error registering the subscription.

See Also:

IMqttAsyncClient.subscribe(String[], int[], Object, IMqttActionListener)

subscribe

public IMqttToken subscribe(java.lang.String[] topicFilters,
                            int[] qos,
                            java.lang.Object userContext,
                            IMqttActionListener callback)
                     throws MqttException

Description copied from interface: IMqttAsyncClient

Subscribes to multiple topics, each of which may include wildcards.

Provides an optimized way to subscribe to multiple topics compared to subscribing to each one individually.

The IMqttAsyncClient.setCallback(MqttCallback) method should be called before this method, otherwise any received messages will be discarded.

If (@link MqttConnectOptions#setCleanSession(boolean)} was set to true when when connecting to the server then the subscription remains in place until either:

• The client disconnects
• An unsubscribe method is called to un-subscribe the topic

If (@link MqttConnectOptions#setCleanSession(boolean)} was set to false when connecting to the server then the subscription remains in place until either:

• An unsubscribe method is called to unsubscribe the topic
• The next time the client connects with cleanSession set to true
With cleanSession set to false the MQTT server will store messages on behalf of the client when the client is not connected. The next time the client connects with the same client ID the server will deliver the stored messages to the client.

The "topic filter" string used when subscribing may contain special characters, which allow you to subscribe to multiple topics at once.

The topic level separator is used to introduce structure into the topic, and can therefore be specified within the topic for that purpose. The multi-level wildcard and single-level wildcard can be used for subscriptions, but they cannot be used within a topic by the publisher of a message.

Topic level separator

The forward slash (/) is used to separate each level within a topic tree and provide a hierarchical structure to the topic space. The use of the topic level separator is significant when the two wildcard characters are encountered in topics specified by subscribers.

Multi-level wildcard

The number sign (#) is a wildcard character that matches any number of levels within a topic. For example, if you subscribe to finance/stock/ibm/#, you receive messages on these topics:

   finance/stock/ibm
   finance/stock/ibm/closingprice
   finance/stock/ibm/currentprice

The multi-level wildcard can represent zero or more levels. Therefore, finance/# can also match the singular finance, where # represents zero levels. The topic level separator is meaningless in this context, because there are no levels to separate.

The multi-level wildcard can be specified only on its own or next to the topic level separator character. Therefore, # and finance/# are both valid, but finance# is not valid. The multi-level wildcard must be the last character used within the topic tree. For example, finance/# is valid but finance/#/closingprice is not valid.

Single-level wildcard

The plus sign (+) is a wildcard character that matches only one topic level. For example, finance/stock/+ matches finance/stock/ibm and finance/stock/xyz, but not finance/stock/ibm/closingprice. Also, because the single-level wildcard matches only a single level, finance/+ does not match finance.

Use the single-level wildcard at any level in the topic tree, and in conjunction with the multilevel wildcard. Specify the single-level wildcard next to the topic level separator, except when it is specified on its own. Therefore, + and finance/+ are both valid, but finance+ is not valid. The single-level wildcard can be used at the end of the topic tree or within the topic tree. For example, finance/+ and finance/+/ibm are both valid.

The method returns control before the subscribe completes. Completion can be tracked by:

• Waiting on the supplied token MqttToken.waitForCompletion() or
• Passing in a callback IMqttActionListener to this method

Specified by:

subscribe in interface IMqttAsyncClient

Parameters:

topicFilters - one or more topics to subscribe to, which can include wildcards

qos - the maximum quality of service to subscribe each topic at.Messages published at a lower quality of service will be received at the published QoS. Messages published at a higher quality of service will be received using the QoS specified on the subscribe.

userContext - optional object used to pass context to the callback. Use null if not required.

callback - optional listener that will be notified when subscribe has completed

Returns:

token used to track and wait for the subscribe to complete. The token will be passed to callback methods if set.

Throws:

MqttException - if there was an error registering the subscription.

subscribe

public IMqttToken subscribe(java.lang.String topicFilter,
                            int qos,
                            java.lang.Object userContext,
                            IMqttActionListener callback,
                            IMqttMessageListener messageListener)
                     throws MqttException

Description copied from interface: IMqttAsyncClient

Subscribe to a topic, which may include wildcards.

Specified by:

subscribe in interface IMqttAsyncClient

Parameters:

topicFilter - the topic to subscribe to, which can include wildcards.

qos - the maximum quality of service at which to subscribe. Messages published at a lower quality of service will be received at the published QoS. Messages published at a higher quality of service will be received using the QoS specified on the subscribe.

userContext - optional object used to pass context to the callback. Use null if not required.

callback - optional listener that will be notified when subscribe has completed

messageListener - a callback to handle incoming messages

Returns:

token used to track and wait for the subscribe to complete. The token will be passed to callback methods if set.

Throws:

MqttException - if there was an error registering the subscription.

See Also:

IMqttAsyncClient.subscribe(String[], int[], Object, IMqttActionListener)

subscribe

public IMqttToken subscribe(java.lang.String topicFilter,
                            int qos,
                            IMqttMessageListener messageListener)
                     throws MqttException

Description copied from interface: IMqttAsyncClient

Subscribe to a topic, which may include wildcards.

Specified by:

subscribe in interface IMqttAsyncClient

Parameters:

topicFilter - the topic to subscribe to, which can include wildcards.

qos - the maximum quality of service at which to subscribe. Messages published at a lower quality of service will be received at the published QoS. Messages published at a higher quality of service will be received using the QoS specified on the subscribe.

messageListener - a callback to handle incoming messages

Returns:

token used to track and wait for the subscribe to complete. The token will be passed to callback methods if set.

Throws:

MqttException - if there was an error registering the subscription.

See Also:

IMqttAsyncClient.subscribe(String[], int[], Object, IMqttActionListener)

subscribe

public IMqttToken subscribe(java.lang.String[] topicFilters,
                            int[] qos,
                            IMqttMessageListener[] messageListeners)
                     throws MqttException

Description copied from interface: IMqttAsyncClient

Subscribe to multiple topics, each of which may include wildcards.

Provides an optimized way to subscribe to multiple topics compared to subscribing to each one individually.

Specified by:

subscribe in interface IMqttAsyncClient

Parameters:

topicFilters - one or more topics to subscribe to, which can include wildcards

qos - the maximum quality of service at which to subscribe. Messages published at a lower quality of service will be received at the published QoS. Messages published at a higher quality of service will be received using the QoS specified on the subscribe.

messageListeners - one or more callbacks to handle incoming messages

Returns:

token used to track and wait for the subscribe to complete. The token will be passed to callback methods if set.

Throws:

MqttException - if there was an error registering the subscription.

See Also:

IMqttAsyncClient.subscribe(String[], int[], Object, IMqttActionListener)

subscribe

public IMqttToken subscribe(java.lang.String[] topicFilters,
                            int[] qos,
                            java.lang.Object userContext,
                            IMqttActionListener callback,
                            IMqttMessageListener[] messageListeners)
                     throws MqttException

Description copied from interface: IMqttAsyncClient

Subscribe to multiple topics, each of which may include wildcards.

Provides an optimized way to subscribe to multiple topics compared to subscribing to each one individually.

Specified by:

subscribe in interface IMqttAsyncClient

Parameters:

topicFilters - one or more topics to subscribe to, which can include wildcards

qos - the maximum quality of service at which to subscribe. Messages published at a lower quality of service will be received at the published QoS. Messages published at a higher quality of service will be received using the QoS specified on the subscribe.

userContext - optional object used to pass context to the callback. Use null if not required.

callback - optional listener that will be notified when subscribe has completed

messageListeners - one or more callbacks to handle incoming messages

Returns:

token used to track and wait for the subscribe to complete. The token will be passed to callback methods if set.

Throws:

MqttException - if there was an error registering the subscription.

See Also:

IMqttAsyncClient.subscribe(String[], int[], Object, IMqttActionListener)

unsubscribe

public IMqttToken unsubscribe(java.lang.String topicFilter,
                              java.lang.Object userContext,
                              IMqttActionListener callback)
                       throws MqttException

Description copied from interface: IMqttAsyncClient

Requests the server unsubscribe the client from a topics.

Specified by:

unsubscribe in interface IMqttAsyncClient

Parameters:

topicFilter - the topic to unsubscribe from. It must match a topicFilter specified on an earlier subscribe.

userContext - optional object used to pass context to the callback. Use null if not required.

callback - optional listener that will be notified when unsubscribe has completed

Returns:

token used to track and wait for the unsubscribe to complete. The token will be passed to callback methods if set.

Throws:

MqttException - if there was an error unregistering the subscription.

See Also:

IMqttAsyncClient.unsubscribe(String[], Object, IMqttActionListener)

unsubscribe

public IMqttToken unsubscribe(java.lang.String topicFilter)
                       throws MqttException

Description copied from interface: IMqttAsyncClient

Requests the server unsubscribe the client from a topic.

Specified by:

unsubscribe in interface IMqttAsyncClient

Parameters:

topicFilter - the topic to unsubscribe from. It must match a topicFilter specified on an earlier subscribe.

Returns:

token used to track and wait for the unsubscribe to complete. The token will be passed to callback methods if set.

Throws:

MqttException - if there was an error unregistering the subscription.

See Also:

IMqttAsyncClient.unsubscribe(String[], Object, IMqttActionListener)

unsubscribe

public IMqttToken unsubscribe(java.lang.String[] topicFilters)
                       throws MqttException

Description copied from interface: IMqttAsyncClient

Requests the server unsubscribe the client from one or more topics.

Specified by:

unsubscribe in interface IMqttAsyncClient

Parameters:

topicFilters - one or more topics to unsubscribe from. Each topicFilter must match one specified on an earlier subscribe. *

Returns:

token used to track and wait for the unsubscribe to complete. The token will be passed to callback methods if set.

Throws:

MqttException - if there was an error unregistering the subscription.

See Also:

IMqttAsyncClient.unsubscribe(String[], Object, IMqttActionListener)

unsubscribe

public IMqttToken unsubscribe(java.lang.String[] topicFilters,
                              java.lang.Object userContext,
                              IMqttActionListener callback)
                       throws MqttException

Description copied from interface: IMqttAsyncClient

Requests the server unsubscribe the client from one or more topics.

Unsubcribing is the opposite of subscribing. When the server receives the unsubscribe request it looks to see if it can find a matching subscription for the client and then removes it. After this point the server will send no more messages to the client for this subscription.

The topic(s) specified on the unsubscribe must match the topic(s) specified in the original subscribe request for the unsubscribe to succeed

The method returns control before the unsubscribe completes. Completion can be tracked by:

• Waiting on the returned token MqttToken.waitForCompletion() or
• Passing in a callback IMqttActionListener to this method

Specified by:

unsubscribe in interface IMqttAsyncClient

Parameters:

topicFilters - one or more topics to unsubscribe from. Each topicFilter must match one specified on an earlier subscribe.

userContext - optional object used to pass context to the callback. Use null if not required.

callback - optional listener that will be notified when unsubscribe has completed

Returns:

token used to track and wait for the unsubscribe to complete. The token will be passed to callback methods if set.

Throws:

MqttException - if there was an error unregistering the subscription.

setCallback

public void setCallback(MqttCallback callback)

Description copied from interface: IMqttAsyncClient

Sets a callback listener to use for events that happen asynchronously.

There are a number of events that the listener will be notified about. These include:

• A new message has arrived and is ready to be processed
• The connection to the server has been lost
• Delivery of a message to the server has completed

Other events that track the progress of an individual operation such as connect and subscribe can be tracked using the MqttToken returned from each non-blocking method or using setting a IMqttActionListener on the non-blocking method.

Specified by:

setCallback in interface IMqttAsyncClient

Parameters:

callback - which will be invoked for certain asynchronous events

See Also:

MqttCallback

setManualAcks

public void setManualAcks(boolean manualAcks)

Description copied from interface: IMqttAsyncClient

If manualAcks is set to true, then on completion of the messageArrived callback the MQTT acknowledgements are not sent. You must call messageArrivedComplete to send those acknowledgements. This allows finer control over when the acks are sent. The default behaviour, when manualAcks is false, is to send the MQTT acknowledgements automatically at the successful completion of the messageArrived callback method.

Specified by:

setManualAcks in interface IMqttAsyncClient

messageArrivedComplete

public void messageArrivedComplete(int messageId,
                                   int qos)
                            throws MqttException

Description copied from interface: IMqttAsyncClient

Indicate that the application has completed processing the message with id messageId. This will cause the MQTT acknowledgement to be sent to the server.

Specified by:

messageArrivedComplete in interface IMqttAsyncClient

Parameters:

messageId - the MQTT message id to be acknowledged

qos - the MQTT QoS of the message to be acknowledged

Throws:

MqttException

generateClientId

public static java.lang.String generateClientId()

Returns a randomly generated client identifier based on the the fixed prefix (paho) and the system time.

When cleanSession is set to false, an application must ensure it uses the same client identifier when it reconnects to the server to resume state and maintain assured message delivery.

Returns:

a generated client identifier

See Also:

MqttConnectOptions.setCleanSession(boolean)

getPendingDeliveryTokens

public IMqttDeliveryToken[] getPendingDeliveryTokens()

Description copied from interface: IMqttAsyncClient

Returns the delivery tokens for any outstanding publish operations.

If a client has been restarted and there are messages that were in the process of being delivered when the client stopped this method returns a token for each in-flight message enabling the delivery to be tracked Alternately the MqttCallback.deliveryComplete(IMqttDeliveryToken) callback can be used to track the delivery of outstanding messages.

If a client connects with cleanSession true then there will be no delivery tokens as the cleanSession option deletes all earlier state. For state to be remembered the client must connect with cleanSession set to false

Specified by:

getPendingDeliveryTokens in interface IMqttAsyncClient

Returns:

zero or more delivery tokens

publish

public IMqttDeliveryToken publish(java.lang.String topic,
                                  byte[] payload,
                                  int qos,
                                  boolean retained,
                                  java.lang.Object userContext,
                                  IMqttActionListener callback)
                           throws MqttException,
                                  MqttPersistenceException

Description copied from interface: IMqttAsyncClient

Publishes a message to a topic on the server.

A convenience method, which will create a new MqttMessage object with a byte array payload and the specified QoS, and then publish it.

Specified by:

publish in interface IMqttAsyncClient

Parameters:

topic - to deliver the message to, for example "finance/stock/ibm".

payload - the byte array to use as the payload

qos - the Quality of Service to deliver the message at. Valid values are 0, 1 or 2.

retained - whether or not this message should be retained by the server.

userContext - optional object used to pass context to the callback. Use null if not required.

callback - optional listener that will be notified when message delivery hsa completed to the requested quality of service

Returns:

token used to track and wait for the publish to complete. The token will be passed to any callback that has been set.

Throws:

MqttPersistenceException - when a problem occurs storing the message

MqttException - for other errors encountered while publishing the message. For instance client not connected.

See Also:

IMqttAsyncClient.publish(String, MqttMessage, Object, IMqttActionListener), MqttMessage.setQos(int), MqttMessage.setRetained(boolean)

publish

public IMqttDeliveryToken publish(java.lang.String topic,
                                  byte[] payload,
                                  int qos,
                                  boolean retained)
                           throws MqttException,
                                  MqttPersistenceException

Description copied from interface: IMqttAsyncClient

Publishes a message to a topic on the server.

A convenience method, which will create a new MqttMessage object with a byte array payload and the specified QoS, and then publish it.

Specified by:

publish in interface IMqttAsyncClient

Parameters:

topic - to deliver the message to, for example "finance/stock/ibm".

payload - the byte array to use as the payload

qos - the Quality of Service to deliver the message at. Valid values are 0, 1 or 2.

retained - whether or not this message should be retained by the server.

Returns:

token used to track and wait for the publish to complete. The token will be passed to any callback that has been set.

Throws:

MqttPersistenceException - when a problem occurs storing the message

MqttException - for other errors encountered while publishing the message. For instance if too many messages are being processed.

See Also:

IMqttAsyncClient.publish(String, MqttMessage, Object, IMqttActionListener), MqttMessage.setQos(int), MqttMessage.setRetained(boolean)

publish

public IMqttDeliveryToken publish(java.lang.String topic,
                                  MqttMessage message)
                           throws MqttException,
                                  MqttPersistenceException

Description copied from interface: IMqttAsyncClient

Publishes a message to a topic on the server. Takes an MqttMessage message and delivers it to the server at the requested quality of service.

Specified by:

publish in interface IMqttAsyncClient

Parameters:

topic - to deliver the message to, for example "finance/stock/ibm".

message - to deliver to the server

Returns:

token used to track and wait for the publish to complete. The token will be passed to any callback that has been set.

Throws:

MqttPersistenceException - when a problem occurs storing the message

MqttException - for other errors encountered while publishing the message. For instance client not connected.

See Also:

IMqttAsyncClient.publish(String, MqttMessage, Object, IMqttActionListener)

publish

public IMqttDeliveryToken publish(java.lang.String topic,
                                  MqttMessage message,
                                  java.lang.Object userContext,
                                  IMqttActionListener callback)
                           throws MqttException,
                                  MqttPersistenceException

Description copied from interface: IMqttAsyncClient

Publishes a message to a topic on the server.

Once this method has returned cleanly, the message has been accepted for publication by the client and will be delivered on a background thread. In the event the connection fails or the client stops. Messages will be delivered to the requested quality of service once the connection is re-established to the server on condition that:

• The connection is re-established with the same clientID
• The original connection was made with (@link MqttConnectOptions#setCleanSession(boolean)} set to false
• The connection is re-established with (@link MqttConnectOptions#setCleanSession(boolean)} set to false
• Depending when the failure occurs QoS 0 messages may not be delivered.

When building an application, the design of the topic tree should take into account the following principles of topic name syntax and semantics:

• A topic must be at least one character long.
• Topic names are case sensitive. For example, ACCOUNTS and Accounts are two different topics.
• Topic names can include the space character. For example, Accounts payable is a valid topic.
• A leading "/" creates a distinct topic. For example, /finance is different from finance. /finance matches "+/+" and "/+", but not "+".
• Do not include the null character (Unicode \x0000) in any topic.

The following principles apply to the construction and content of a topic tree:

• The length is limited to 64k but within that there are no limits to the number of levels in a topic tree.
• There can be any number of root nodes; that is, there can be any number of topic trees.

The method returns control before the publish completes. Completion can be tracked by:

• Setting an IMqttAsyncClient.setCallback(MqttCallback) where the MqttCallback.deliveryComplete(IMqttDeliveryToken) method will be called.
• Waiting on the returned token MqttToken.waitForCompletion() or
• Passing in a callback IMqttActionListener to this method

Specified by:

publish in interface IMqttAsyncClient

Parameters:

topic - to deliver the message to, for example "finance/stock/ibm".

message - to deliver to the server

userContext - optional object used to pass context to the callback. Use null if not required.

callback - optional listener that will be notified when message delivery has completed to the requested quality of service

Returns:

token used to track and wait for the publish to complete. The token will be passed to callback methods if set.

Throws:

MqttPersistenceException - when a problem occurs storing the message

MqttException - for other errors encountered while publishing the message. For instance client not connected.

See Also:

MqttMessage

reconnect

public void reconnect()
               throws MqttException

User triggered attempt to reconnect

Throws:

MqttException

setBufferOpts

public void setBufferOpts(DisconnectedBufferOptions bufferOpts)

Sets the DisconnectedBufferOptions for this client

Parameters:

bufferOpts -

getBufferedMessageCount

public int getBufferedMessageCount()

getBufferedMessage

public MqttMessage getBufferedMessage(int bufferIndex)

deleteBufferedMessage

public void deleteBufferedMessage(int bufferIndex)

close

public void close()
           throws MqttException

Description copied from interface: IMqttAsyncClient

Close the client Releases all resource associated with the client. After the client has been closed it cannot be reused. For instance attempts to connect will fail.

Specified by:

close in interface IMqttAsyncClient

Throws:

MqttException - if the client is not disconnected.

getDebug

public Debug getDebug()

Return a debug object that can be used to help solve problems.