TxRxControl (sdn-apidoc 2.0.0 API)

```
public interface TxRxControl
```
Message transmission recording control API.
This interface has two functions:
- It provides the controls to enable the recording of all transmitted and received OpenFlow messages for a short period of time.
- It exposes the consumer side of the TX/RX message queue, so that the recorded messages can be retrieved.
The queue implementation is an unbounded, blocking queue.
Note that the messages reported through this mechanism include pseudo-messages marking the initial connection requests from the switches, as well as the "handshaking" and "heartbeat" messages handled internally by the controller. These messages are not visible above ControllerService.
The intended use of this mechanism is to allow a logging service to record all the OpenFlow messages for a brief span of time, for field support or debugging purposes.
See Also:
ControllerMx

Method Summary

Methods
Modifier and Type	Method and Description
`boolean`	`isEmpty()` Returns `true` if the TX/RX queue contains no elements.
`boolean`	`isRecording()` Returns true if TX/RX messages are being recorded.
`boolean`	`isTriggerWaiting()` Returns true if a trigger has been set, but has not yet fired.
`MessageEvent`	`poll(long timeoutMs)` Retrieves and removes the head of the TX/RX message event queue, waiting up to the specified number of milliseconds for an element to become available.
`int`	`size()` Returns the number of elements in the TX/RX queue.
`void`	`startRecording(int seconds)` Enables message recording for the specified amount of time, starting immediately.
`void`	`stopRecording()` Shuts off recording of messages immediately, and clears any trigger that might have been set.
`MessageEvent`	`take()` Retrieves and removes the head of the TX/RX message event queue, waiting if necessary until an element becomes available.
`void`	`triggerRecording(TxRxTrigger trigger, int seconds)` Enables message recording for the specified amount of time, starting when the specified trigger condition is met.

- Method Detail
  - startRecording
```
void startRecording(int seconds)
```
    Enables message recording for the specified amount of time, starting immediately. After the specified amount of time has elapsed, recording will shut off automatically.
    An exception will be thrown if we are already recording, or if a trigger has been set and is waiting to fire. To clear this condition, call stopRecording().
    
    Parameters:
    seconds - the number of seconds to elapse before message recording is shut off
    
    Throws:
    
    IllegalArgumentException - if seconds is < 1
    
    IllegalStateException - if recording is already in progress
  - triggerRecording
```
void triggerRecording(TxRxTrigger trigger,
                    int seconds)
```
    Enables message recording for the specified amount of time, starting when the specified trigger condition is met. After the specified amount of time has elapsed, recording will shut off automatically.
    An exception will be thrown if we are already recording, or if a trigger has been set and is waiting to fire. To clear this condition, call stopRecording().
    This is a place holder method: not yet implemented.
    
    Parameters:
    trigger - the condition required to trigger the start of recording
    seconds - the number of seconds to elapse after recording has started, before message recording is shut off
    
    Throws:
    
    NullPointerException - if trigger is null
    
    IllegalArgumentException - if seconds is < 1
    
    IllegalStateException - if recording is already in progress
  - stopRecording
```
void stopRecording()
```
    Shuts off recording of messages immediately, and clears any trigger that might have been set.
  - isRecording
```
boolean isRecording()
```
    Returns true if TX/RX messages are being recorded.
    
    Returns:
    true if TX/RX messages are being recorded
  - isTriggerWaiting
```
boolean isTriggerWaiting()
```
    Returns true if a trigger has been set, but has not yet fired.
    
    Returns:
    true if a trigger is set but has not been fired
  - take
```
MessageEvent take()
                  throws InterruptedException
```
    Retrieves and removes the head of the TX/RX message event queue, waiting if necessary until an element becomes available.
    This method blocks if there are no elements in the queue.
    
    Returns:
    the head of the TX/RX queue
    
    Throws:
    
    InterruptedException - if interrupted while waiting
  - poll
```
MessageEvent poll(long timeoutMs)
                  throws InterruptedException
```
    Retrieves and removes the head of the TX/RX message event queue, waiting up to the specified number of milliseconds for an element to become available.
    
    Parameters:
    timeoutMs - the maximum number of milliseconds to wait
    
    Returns:
    the head of the TX/RX queue, or null if the specified wait time elapses before an element is available
    
    Throws:
    
    InterruptedException - if interrupted while waiting
  - size
```
int size()
```
    Returns the number of elements in the TX/RX queue.
    
    Returns:
    the number of elements in the queue
  - isEmpty
```
boolean isEmpty()
```
    Returns true if the TX/RX queue contains no elements.
    
    Returns:
    true if the queue contains no elements

Interface TxRxControl

Method Summary

Method Detail

startRecording

triggerRecording

stopRecording

isRecording

isTriggerWaiting

take

poll

size

isEmpty