IMqttToken

All Known Subinterfaces:

IMqttDeliveryToken

All Known Implementing Classes:

MqttDeliveryToken, MqttToken
```
public interface IMqttToken
```
Provides a mechanism for tracking the completion of an asynchronous task.
When using the asynchronous/non-blocking MQTT programming interface all methods/operations that take any time (and in particular those that involve any network operation) return control to the caller immediately. The operation then proceeds to run in the background so as not to block the invoking thread. An IMqttToken is used to track the state of the operation. An application can use the token to wait for an operation to complete. A token is passed to callbacks once the operation completes and provides context linking it to the original request. A token is associated with a single operation.

An action is in progress until either:
- isComplete() returns true or
- getException() is not null.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`IMqttActionListener`	`getActionCallback()` Return the async listener for this token.
`IMqttAsyncClient`	`getClient()` Returns the MQTT client that is responsible for processing the asynchronous action
`MqttException`	`getException()` Returns an exception providing more detail if an operation failed.
`int[]`	`getGrantedQos()` Returns the granted QoS list from a suback
`int`	`getMessageId()` Returns the message ID of the message that is associated with the token.
`MqttWireMessage`	`getResponse()` Returns the response wire message
`boolean`	`getSessionPresent()` Returns the session present flag from a connack
`java.lang.String[]`	`getTopics()` Returns the topic string(s) for the action being tracked by this token.
`java.lang.Object`	`getUserContext()` Retrieve the context associated with an action.
`boolean`	`isComplete()` Returns whether or not the action has finished.
`void`	`setActionCallback(IMqttActionListener listener)` Register a listener to be notified when an action completes.
`void`	`setUserContext(java.lang.Object userContext)` Store some context associated with an action.
`void`	`waitForCompletion()` Blocks the current thread until the action this token is associated with has completed.
`void`	`waitForCompletion(long timeout)` Blocks the current thread until the action this token is associated with has completed.

- Method Detail
  - waitForCompletion
```
void waitForCompletion()
                throws MqttException
```
    Blocks the current thread until the action this token is associated with has completed.
    
    Throws:
    
    MqttException - if there was a problem with the action associated with the token.
    
    See Also:
    
    waitForCompletion(long)
  - waitForCompletion
```
void waitForCompletion(long timeout)
                throws MqttException
```
    Blocks the current thread until the action this token is associated with has completed.
    The timeout specifies the maximum time it will block for. If the action completes before the timeout then control returns immediately, if not it will block until the timeout expires.
    
    If the action being tracked fails or the timeout expires an exception will be thrown. In the event of a timeout the action may complete after timeout.
    
    Parameters:
    
    timeout - the maximum amount of time to wait for, in milliseconds.
    
    Throws:
    
    MqttException - if there was a problem with the action associated with the token.
  - isComplete
```
boolean isComplete()
```
    Returns whether or not the action has finished.
    True will be returned both in the case where the action finished successfully and in the case where it failed. If the action failed getException() will be non null.
  - getException
```
MqttException getException()
```
    Returns an exception providing more detail if an operation failed.
    While an action in in progress and when an action completes successfully null will be returned. Certain errors like timeout or shutting down will not set the exception as the action has not failed or completed at that time
    
    Returns:
    
    exception may return an exception if the operation failed. Null will be returned while action is in progress and if action completes successfully.
  - setActionCallback
```
void setActionCallback(IMqttActionListener listener)
```
    Register a listener to be notified when an action completes.
    Once a listener is registered it will be invoked when the action the token is associated with either succeeds or fails.
    
    Parameters:
    
    listener - to be invoked once the action completes
  - getActionCallback
```
IMqttActionListener getActionCallback()
```
    Return the async listener for this token.
    
    Returns:
    
    listener that is set on the token or null if a listener is not registered.
  - getClient
```
IMqttAsyncClient getClient()
```
    Returns the MQTT client that is responsible for processing the asynchronous action
  - getTopics
```
java.lang.String[] getTopics()
```
    Returns the topic string(s) for the action being tracked by this token. If the action has not been initiated or the action has not topic associated with it such as connect then null will be returned.
    
    Returns:
    
    the topic string(s) for the subscribe being tracked by this token or null
  - setUserContext
```
void setUserContext(java.lang.Object userContext)
```
    Store some context associated with an action.
    Allows the caller of an action to store some context that can be accessed from within the ActionListener associated with the action. This can be useful when the same ActionListener is associated with multiple actions
    
    Parameters:
    
    userContext - to associate with an action
  - getUserContext
```
java.lang.Object getUserContext()
```
    Retrieve the context associated with an action.
    Allows the ActionListener associated with an action to retrieve any context that was associated with the action when the action was invoked. If not context was provided null is returned.
    
    Returns:
    
    Object context associated with an action or null if there is none.
  - getMessageId
```
int getMessageId()
```
    Returns the message ID of the message that is associated with the token. A message id of zero will be returned for tokens associated with connect, disconnect and ping operations as there can only ever be one of these outstanding at a time. For other operations the MQTT message id flowed over the network.
  - getGrantedQos
```
int[] getGrantedQos()
```
    Returns the granted QoS list from a suback
  - getSessionPresent
```
boolean getSessionPresent()
```
    Returns the session present flag from a connack
  - getResponse
```
MqttWireMessage getResponse()
```
    Returns the response wire message

Interface IMqttToken

Method Summary

Method Detail

waitForCompletion

waitForCompletion

isComplete

getException

setActionCallback

getActionCallback

getClient

getTopics

setUserContext

getUserContext

getMessageId

getGrantedQos

getSessionPresent

getResponse