code: public void enqueue(TargetTransportPort port, Command command)
     {
        if (_logger.isDebugEnabled())
        {
           _logger.debug("enqueuing command: " + command + ", associated with TargetTransportPort: "
                 + port);
        }
        try
        {
           Task task = this.getTaskFactory().getInstance(port, command);
           assert task != null : "improper task factory implementation returned null task";
           if (_logger.isDebugEnabled())
           {
              _logger.debug("successfully constructed task: " + task);
           }
           this.taskSet.offer(task); // non-blocking, task set sends any errors to transport port
        }
        catch (IllegalRequestException e)
        {
           port.writeResponse(command.getNexus(), command.getCommandReferenceNumber(),
                 Status.CHECK_CONDITION, ByteBuffer.wrap(e.encode()));
        }
     }
docs: operations