```
public interface IMqttClient

                    
```
Enables an application to communicate with an MQTT server using using blocking methods.
This interface allows applications to utilize all features of the MQTT version 3.1 specification including:
- connect
- publish
- subscribe
- unsubscribe
- disconnect
There are two styles of MQTT client, this one and IMqttAsyncClient.
- IMqttClient provides a set of methods that block and return control to the application program once the MQTT action has completed.
- IMqttAsyncClient provides a set of non-blocking methods that return control to the invoking application after initial validation of parameters and state. The main processing is performed in the background so as not to block the application programs thread. This non blocking approach is handy when the application wants to carry on processing while the MQTT action takes place. For instance connecting to an MQTT server can take time, using the non-blocking connect method allows an application to display a busy indicator while the connect action is occurring. Non-blocking methods are particularly useful in event-oriented programs and graphical programs where issuing methods that take time to complete on the the main or GUI thread can cause problems.
The non-blocking client can also be used in a blocking form by turning a non-blocking method into a blocking invocation using the following pattern:
```
 IMqttToken token; token = asyncClient.method(parms).waitForCompletion(); 
```
Using the non-blocking client allows an application to use a mixture of blocking and non-blocking styles. Using the blocking client only allows an application to use one style. The blocking client provides compatibility with earlier versions of the MQTT client.

Method Summary

Modifier and Type	Method	Description
`abstract void`	`connect()`	Connects to an MQTT server using the default options.
`abstract void`	`connect(MqttConnectOptions options)`	Connects to an MQTT server using the specified options.
`abstract void`	`disconnect()`	Disconnects from the server.
`abstract void`	`disconnect(long quiesceTimeout)`	Disconnects from the server.
`abstract void`	`disconnectForcibly()`	Disconnects from the server forcibly to reset all the states.
`abstract void`	`disconnectForcibly(long disconnectTimeout)`	Disconnects from the server forcibly to reset all the states.
`abstract void`	`disconnectForcibly(long quiesceTimeout, long disconnectTimeout)`	Disconnects from the server forcibly to reset all the states.
`abstract void`	`subscribe(String topicFilter)`	Subscribe to a topic, which may include wildcards using a QoS of 1.
`abstract void`	`subscribe(Array<String> topicFilters)`	Subscribes to a one or more topics, which may include wildcards using a QoS of 1.
`abstract void`	`subscribe(String topicFilter, int qos)`	Subscribe to a topic, which may include wildcards.
`abstract void`	`subscribe(Array<String> topicFilters, Array<int> qos)`	Subscribes to multiple topics, each of which may include wildcards.
`abstract void`	`unsubscribe(String topicFilter)`	Requests the server unsubscribe the client from a topic.
`abstract void`	`unsubscribe(Array<String> topicFilters)`	Requests the server unsubscribe the client from one or more topics.
`abstract void`	`publish(String topic, Array<byte> payload, int qos, boolean retained)`	Publishes a message to a topic on the server and return once it is delivered.
`abstract void`	`publish(String topic, MqttMessage message)`	Publishes a message to a topic on the server.
`abstract void`	`setCallback(MqttCallback callback)`	Sets the callback listener to use for events that happen asynchronously.
`abstract MqttTopic`	`getTopic(String topic)`	Get a topic object which can be used to publish messages.
`abstract boolean`	`isConnected()`	Determines if this client is currently connected to the server.
`abstract String`	`getClientId()`	Returns the client ID used by this client.
`abstract String`	`getServerURI()`	Returns the address of the server used by this client, as a URI.
`abstract Array<IMqttDeliveryToken>`	`getPendingDeliveryTokens()`	Returns the delivery tokens for any outstanding publish operations.
`abstract void`	`close()`	Close the client Releases all resource associated with the client.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - connect
```
 abstract void connect()
```
    Connects to an MQTT server using the default options.
    The default options are specified in MqttConnectOptions class.
  - connect
```
 abstract void connect(MqttConnectOptions options)
```
    Connects to an MQTT server using the specified options.
    The server to connect to is specified on the constructor. It is recommended to call setCallback 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
    
    Parameters:
    
    options - a set of connection parameters that override the defaults.
  - disconnect
```
 abstract void disconnect()
```
    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.
  - disconnect
```
 abstract void disconnect(long quiesceTimeout)
```
    Disconnects from the server.
    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
    
    Parameters:
    
    quiesceTimeout - the amount of time in milliseconds to allow for existing work to finish before disconnecting.
  - disconnectForcibly
```
 abstract void disconnectForcibly()
```
    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.
  - disconnectForcibly
```
 abstract void disconnectForcibly(long disconnectTimeout)
```
    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.
    
    Parameters:
    
    disconnectTimeout - the amount of time in milliseconds to allow send disconnect packet to server.
  - disconnectForcibly
```
 abstract void disconnectForcibly(long quiesceTimeout, long disconnectTimeout)
```
    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.
    
    Parameters:
    
    quiesceTimeout - the amount of time in milliseconds to allow for existing work to finish before disconnecting.
    
    disconnectTimeout - the amount of time in milliseconds to allow send disconnect packet to server.
  - subscribe
```
 abstract void subscribe(String topicFilter)
```
    Subscribe to a topic, which may include wildcards using a QoS of 1.
    
    Parameters:
    
    topicFilter - the topic to subscribe to, which can include wildcards.
  - subscribe
```
 abstract void subscribe(Array<String> topicFilters)
```
    Subscribes to a one or more topics, which may include wildcards using a QoS of 1.
    
    Parameters:
    
    topicFilters - the topic to subscribe to, which can include wildcards.
  - subscribe
```
 abstract void subscribe(String topicFilter, int qos)
```
    Subscribe to a topic, which may include wildcards.
    
    Parameters:
    
    topicFilter - the topic to subscribe to, which can include wildcards.
    
    qos - the maximum quality of service at which to subscribe.
  - subscribe
```
 abstract void subscribe(Array<String> topicFilters, Array<int> qos)
```
    Subscribes to multiple topics, each of which may include wildcards.
    The setCallback 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 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.
    This is a blocking method that returns once subscribe completes
    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.
  - unsubscribe
```
 abstract void unsubscribe(String topicFilter)
```
    Requests the server unsubscribe the client from a topic.
    
    Parameters:
    
    topicFilter - the topic to unsubscribe from.
  - unsubscribe
```
 abstract void unsubscribe(Array<String> topicFilters)
```
    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 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
    
    Parameters:
    
    topicFilters - one or more topics to unsubscribe from.
  - publish
```
 abstract void publish(String topic, Array<byte> payload, int qos, boolean retained)
```
    Publishes a message to a topic on the server and return once it is delivered.
    This 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.
    
    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.
    
    retained - whether or not this message should be retained by the server.
  - publish
```
 abstract void publish(String topic, MqttMessage message)
```
    Publishes a message to a topic on the server.
    Delivers 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:
    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
    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:
    Register a setCallback callback on the client and the delivery complete callback will be notified once a delivery of a message completes
    or call 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:
    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.
    This is a blocking method that returns once publish completes
    *
    Parameters:
    
    topic - to deliver the message to, for example "finance/stock/ibm".
    
    message - to delivery to the server
  - setCallback
```
 abstract void setCallback(MqttCallback callback)
```
    Sets the callback listener to use for events that happen asynchronously.
    There are a number of events that 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 passed to the operation
    Parameters:
    
    callback - the class to callback when for events related to the client
  - getTopic
```
 abstract MqttTopic getTopic(String topic)
```
    Get a topic object which can be used to publish messages.
    An alternative method that should be used in preference to this one when publishing a message is:
    publish to publish a message in a blocking manner
    or use publish methods on the non-blocking client like publish
    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.
    Parameters:
    
    topic - the topic to use, for example "finance/stock/ibm".
  - isConnected
```
 abstract boolean isConnected()
```
    Determines if this client is currently connected to the server.
  - getClientId
```
 abstract String getClientId()
```
    Returns the client ID used by this client.
    All clients connected to the same server or server farm must have a unique ID.
  - getServerURI
```
 abstract String getServerURI()
```
    Returns the address of the server used by this client, as a URI.
    The format is the same as specified on the constructor.
  - getPendingDeliveryTokens
```
 abstract Array<IMqttDeliveryToken> getPendingDeliveryTokens()
```
    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 will return a token for each message enabling the delivery to be tracked Alternately the deliveryComplete 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
  - close
```
 abstract void close()
```
    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.

Interface IMqttClient

Method Summary

Methods inherited from class java.lang.Object

Method Detail

connect

connect

disconnect

disconnect

disconnectForcibly

disconnectForcibly

disconnectForcibly

subscribe

subscribe

subscribe

subscribe

unsubscribe

unsubscribe

publish

publish

setCallback

getTopic

isConnected

getClientId

getServerURI

getPendingDeliveryTokens

close