Null Channel

The Null Channel is PollableChannel used primarily for testing purposes. The sending methods always return true, indicating the operation is successful, while the receiving methods always get a null message. Internally, the code does not create any queues, but returns true on a send operation or null on a receive operation immediately. For the complete picture (and if you are curious like me), see the actual implementation of the send and receive methods in the framework:

// This is the framework class implementation
public class NullChannel implements PollableChannel {
  // send will always return true
  public boolean send(Message<?> message) {
    if (logger.isDebugEnabled()) {
      logger.debug("message sent to null channel: " + message);
    }
    return true;
  }

  // receive will return null always
  public Message<?> receive() {
    if (logger.isDebugEnabled()) {
      logger.debug("receive called on null channel");
    }
    return null;
  }
...
}