public class MqttClient extends java.lang.Object implements IMqttClient
This class implements the blocking IMqttClient client interface where all
actions block until they have completed (or timed out).
This implementation is compatible with all Java SE runtimes from 1.4.2 and up.
An application can connect to an MQTT server using:
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 it cleared when a client disconnects. If
connecting with cleanSession set to false, to provide reliable message delivery
then a persistent message store should be used such as the default one.
The message store interface is pluggable. Different stores can be used by implementing
the MqttClientPersistence interface and passing it to the clients constructor.
IMqttClient| Constructor and Description |
|---|
MqttClient(java.lang.String serverURI,
java.lang.String clientId)
Create an MqttClient that can be used to communicate with an MQTT server.
|
MqttClient(java.lang.String serverURI,
java.lang.String clientId,
MqttClientPersistence persistence)
Create an MqttClient that can be used to communicate with an MQTT server.
|
| Modifier and Type | Method and Description |
|---|---|
void |
close()
Close the client
Releases all resource associated with the client.
|
void |
connect()
Connects to an MQTT server using the default options.
|
void |
connect(MqttConnectOptions options)
Connects to an MQTT server using the specified options.
|
IMqttToken |
connectWithResult(MqttConnectOptions options)
Connects to an MQTT server using the specified options.
|
void |
disconnect()
Disconnects from the server.
|
void |
disconnect(long quiesceTimeout)
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 current user's login
name and the system time.
|
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, as a URI.
|
long |
getTimeToWait()
Return the maximum time to wait for an action to complete.
|
MqttTopic |
getTopic(java.lang.String topic)
Get a topic object which can be used to publish messages.
|
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.
|
void |
publish(java.lang.String topic,
byte[] payload,
int qos,
boolean retained)
Publishes a message to a topic on the server and return once it is delivered.
|
void |
publish(java.lang.String topic,
MqttMessage message)
Publishes a message to a topic on the server.
|
void |
reconnect() |
void |
setCallback(MqttCallback callback)
Sets the 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.
|
void |
setTimeToWait(long timeToWaitInMillis)
Set the maximum time to wait for an action to complete.
|
void |
subscribe(java.lang.String topicFilter)
Subscribe to a topic, which may include wildcards using a QoS of 1.
|
void |
subscribe(java.lang.String[] topicFilters)
Subscribes to a one or more topics, which may include wildcards using a QoS of 1.
|
void |
subscribe(java.lang.String[] topicFilters,
IMqttMessageListener[] messageListeners)
Subscribes to a one or more topics, which may include wildcards using a QoS of 1.
|
void |
subscribe(java.lang.String[] topicFilters,
int[] qos)
Subscribes to multiple topics, each of which may include wildcards.
|
void |
subscribe(java.lang.String[] topicFilters,
int[] qos,
IMqttMessageListener[] messageListeners)
Subscribes to multiple topics, each of which may include wildcards.
|
void |
subscribe(java.lang.String topicFilter,
IMqttMessageListener messageListener)
Subscribe to a topic, which may include wildcards using a QoS of 1.
|
void |
subscribe(java.lang.String topicFilter,
int qos)
Subscribe to a topic, which may include wildcards.
|
void |
subscribe(java.lang.String topicFilter,
int qos,
IMqttMessageListener messageListener)
Subscribe to a topic, which may include wildcards.
|
void |
unsubscribe(java.lang.String topicFilter)
Requests the server unsubscribe the client from a topic.
|
void |
unsubscribe(java.lang.String[] topicFilters)
Requests the server unsubscribe the client from one or more topics.
|
public MqttClient(java.lang.String serverURI,
java.lang.String clientId)
throws MqttException
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:1883ssl://localhost:8883tcp://" 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:
SSLSocketFactory - applications can
use MqttConnectOptions.setSocketFactory(SocketFactory) to supply
a factory with the appropriate SSL settings.MqttConnectOptions.setSSLProperties(Properties).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 MqttClient(String, String, MqttClientPersistence)
constructor.
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 tojava.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 lengthMqttException - if any other problem was encounteredpublic MqttClient(java.lang.String serverURI,
java.lang.String clientId,
MqttClientPersistence persistence)
throws MqttException
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:1883ssl://localhost:8883tcp://" 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:
SSLSocketFactory - applications can
use MqttConnectOptions.setSocketFactory(SocketFactory) to supply
a factory with the appropriate SSL settings.MqttConnectOptions.setSSLProperties(Properties).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.
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 topersistence - the persistence class to use to store in-flight message. If null then the
default persistence mechanism is usedjava.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 lengthMqttException - if any other problem was encounteredpublic void connect()
throws MqttSecurityException,
MqttException
IMqttClientThe default options are specified in MqttConnectOptions class.
connect in interface IMqttClientMqttSecurityException - when the server rejects the connect for security
reasonsMqttException - for non security related problemsIMqttClient.connect(MqttConnectOptions)public void connect(MqttConnectOptions options) throws MqttSecurityException, MqttException
IMqttClientThe server to connect to is specified on the constructor.
It is recommended to call IMqttClient.setCallback(MqttCallback) prior to
connecting in order that messages destined for the client can be accepted
as soon as the client is connected.
This is a blocking method that returns once connect completes
connect in interface IMqttClientoptions - a set of connection parameters that override the defaults.MqttSecurityException - when the server rejects the connect for security
reasonsMqttException - for non security related problems including communication errorspublic IMqttToken connectWithResult(MqttConnectOptions options) throws MqttSecurityException, MqttException
IMqttClientThe server to connect to is specified on the constructor.
It is recommended to call IMqttClient.setCallback(MqttCallback) prior to
connecting in order that messages destined for the client can be accepted
as soon as the client is connected.
This is a blocking method that returns once connect completes
connectWithResult in interface IMqttClientoptions - a set of connection parameters that override the defaults.MqttSecurityException - when the server rejects the connect for security
reasonsMqttException - for non security related problems including communication errorspublic void disconnect()
throws MqttException
IMqttClientAn 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.
disconnect in interface IMqttClientMqttExceptionIMqttClient.disconnect(long)public void disconnect(long quiesceTimeout)
throws MqttException
IMqttClient
The client will wait for all 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 example, it will
wait for the QoS 2 flows from earlier publications to complete. 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 is a blocking method that returns once disconnect completes
disconnect in interface IMqttClientquiesceTimeout - 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.MqttException - if a problem is encountered while disconnectingpublic void disconnectForcibly()
throws MqttException
IMqttClientBecause 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.
disconnectForcibly in interface IMqttClientMqttException - if any unexpected errorpublic void disconnectForcibly(long disconnectTimeout)
throws MqttException
IMqttClientBecause 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.
disconnectForcibly in interface IMqttClientdisconnectTimeout - the amount of time in milliseconds to allow send disconnect packet to server.MqttException - if any unexpected errorpublic void disconnectForcibly(long quiesceTimeout,
long disconnectTimeout)
throws MqttException
IMqttClientBecause 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.
disconnectForcibly in interface IMqttClientquiesceTimeout - 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.MqttException - if any unexpected errorpublic void subscribe(java.lang.String topicFilter)
throws MqttException
IMqttClientsubscribe in interface IMqttClienttopicFilter - the topic to subscribe to, which can include wildcards.MqttException - if there was an error registering the subscription.IMqttClient.subscribe(String[], int[])public void subscribe(java.lang.String[] topicFilters)
throws MqttException
IMqttClientsubscribe in interface IMqttClienttopicFilters - the topic to subscribe to, which can include wildcards.MqttException - if there was an error registering the subscription.IMqttClient.subscribe(String[], int[])public void subscribe(java.lang.String topicFilter,
int qos)
throws MqttException
IMqttClientsubscribe in interface IMqttClienttopicFilter - 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.MqttException - if there was an error registering the subscription.IMqttClient.subscribe(String[], int[])public void subscribe(java.lang.String[] topicFilters,
int[] qos)
throws MqttException
IMqttClientThe IMqttClient.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:
If (@link MqttConnectOptions#setCleanSession(boolean)} was set to false when when connecting to the server then the subscription remains in place until either:
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.
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.
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.
This is a blocking method that returns once subscribe completes
subscribe in interface IMqttClienttopicFilters - 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.MqttException - if there was an error registering the subscription.public void subscribe(java.lang.String topicFilter,
IMqttMessageListener messageListener)
throws MqttException
IMqttClientsubscribe in interface IMqttClienttopicFilter - the topic to subscribe to, which can include wildcards.messageListener - a callback to handle incoming messagesMqttException - if there was an error registering the subscription.IMqttClient.subscribe(String[], int[])public void subscribe(java.lang.String[] topicFilters,
IMqttMessageListener[] messageListeners)
throws MqttException
IMqttClientsubscribe in interface IMqttClienttopicFilters - the topic to subscribe to, which can include wildcards.messageListeners - one or more callbacks to handle incoming messagesMqttException - if there was an error registering the subscription.IMqttClient.subscribe(String[], int[])public void subscribe(java.lang.String topicFilter,
int qos,
IMqttMessageListener messageListener)
throws MqttException
IMqttClientsubscribe in interface IMqttClienttopicFilter - 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 messagesMqttException - if there was an error registering the subscription.IMqttClient.subscribe(String[], int[])public void subscribe(java.lang.String[] topicFilters,
int[] qos,
IMqttMessageListener[] messageListeners)
throws MqttException
IMqttClientThe IMqttClient.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:
If (@link MqttConnectOptions#setCleanSession(boolean)} was set to false when when connecting to the server then the subscription remains in place until either:
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.
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.
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.
This is a blocking method that returns once subscribe completes
subscribe in interface IMqttClienttopicFilters - 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.messageListeners - one or more callbacks to handle incoming messagesMqttException - if there was an error registering the subscription.public void unsubscribe(java.lang.String topicFilter)
throws MqttException
IMqttClientunsubscribe in interface IMqttClienttopicFilter - the topic to unsubscribe from. It must match a topicFilter
specified on the subscribe.MqttException - if there was an error unregistering the subscription.IMqttClient.unsubscribe(String[])public void unsubscribe(java.lang.String[] topicFilters)
throws MqttException
IMqttClientUnsubcribing is the opposite of subscribing. When the server receives the unsubscribe request it looks to see if it can find a 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 subscribe to succeed
This is a blocking method that returns once unsubscribe completes
unsubscribe in interface IMqttClienttopicFilters - one or more topics to unsubscribe from. Each topicFilter
must match one specified on a subscribeMqttException - if there was an error unregistering the subscription.public void publish(java.lang.String topic,
byte[] payload,
int qos,
boolean retained)
throws MqttException,
MqttPersistenceException
IMqttClientThis is a convenience method, which will
create a new MqttMessage object with a byte array payload and the
specified QoS, and then publish it. All other values in the
message will be set to the defaults.
publish in interface IMqttClienttopic - to deliver the message to, for example "finance/stock/ibm".payload - the byte array to use as the payloadqos - 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.MqttPersistenceException - when a problem with storing the messageMqttException - for other errors encountered while publishing the message.
For instance client not connected.IMqttClient.publish(String, MqttMessage),
MqttMessage.setQos(int),
MqttMessage.setRetained(boolean)public void publish(java.lang.String topic,
MqttMessage message)
throws MqttException,
MqttPersistenceException
IMqttClientDelivers a message to the server at the requested quality of service and returns control once the message has been delivered. In the event the connection fails or the client stops, any messages that are in the process of being delivered will be delivered once a connection is re-established to the server on condition that:
In the event that the connection breaks or the client stops it is still possible to determine when the delivery of the message completes. Prior to re-establishing the connection to the server:
IMqttClient.setCallback(MqttCallback) callback on the client and the delivery complete
callback will be notified once a delivery of a message completes
IMqttClient.getPendingDeliveryTokens() which will return a token for each message that
is in-flight. The token can be used to wait for delivery to complete.
When building an application, the design of the topic tree should take into account the following principles of topic name syntax and semantics:
The following principles apply to the construction and content of a topic tree:
This is a blocking method that returns once publish completes
*publish in interface IMqttClienttopic - to deliver the message to, for example "finance/stock/ibm".message - to delivery to the serverMqttPersistenceException - when a problem with storing the messageMqttException - for other errors encountered while publishing the message.
For instance client not connected.public void setTimeToWait(long timeToWaitInMillis)
throws java.lang.IllegalArgumentException
Set the maximum time to wait for an action to complete before returning control to the invoking application. Control is returned when:
timeToWaitInMillis - before the action times out. A value or 0 or -1 will wait until
the action finishes and not timeout.java.lang.IllegalArgumentExceptionpublic long getTimeToWait()
setTimeToWait(long)public void close()
throws MqttException
IMqttClientclose in interface IMqttClientMqttException - if the client is not disconnected.public java.lang.String getClientId()
IMqttClientAll clients connected to the same server or server farm must have a unique ID.
getClientId in interface IMqttClientpublic IMqttDeliveryToken[] getPendingDeliveryTokens()
IMqttClientIf a client has been restarted and there are messages that were in the
process of being delivered when the client stopped this method will
return a token for each 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
getPendingDeliveryTokens in interface IMqttClientpublic java.lang.String getServerURI()
IMqttClientThe format is the same as specified on the constructor.
getServerURI in interface IMqttClientMqttAsyncClient.MqttAsyncClient(String, String)public java.lang.String getCurrentServerURI()
public MqttTopic getTopic(java.lang.String topic)
IMqttClientAn alternative method that should be used in preference to this one when publishing a message is:
publish(String, MqttMessage) to publish a message in a blocking manner
IMqttAsyncClient.publish(String, MqttMessage, Object, IMqttActionListener)
When building an application, the design of the topic tree should take into account the following principles of topic name syntax and semantics:
The following principles apply to the construction and content of a topic tree:
getTopic in interface IMqttClienttopic - the topic to use, for example "finance/stock/ibm".public boolean isConnected()
IMqttClientisConnected in interface IMqttClienttrue if connected, false otherwise.public void setCallback(MqttCallback callback)
IMqttClientThere are a number of events that listener will be notified about. These include
Other events that track the progress of an individual operation such
as connect and subscribe can be tracked using the MqttToken passed to the
operation
setCallback in interface IMqttClientcallback - the class to callback when for events related to the clientMqttCallbackpublic void setManualAcks(boolean manualAcks)
IMqttClientsetManualAcks in interface IMqttClientpublic void messageArrivedComplete(int messageId,
int qos)
throws MqttException
IMqttClientmessageArrivedComplete in interface IMqttClientmessageId - the MQTT message id to be acknowledgedqos - the MQTT QoS of the message to be acknowledgedMqttExceptionpublic static java.lang.String generateClientId()
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.
MqttConnectOptions.setCleanSession(boolean)public void reconnect()
throws MqttException
MqttExceptionpublic Debug getDebug()