/**
 * @file RtecDefaultEventData.idl
 *
 * @brief Define the RtecBase module
 *
 * $Id$
 *
 * TAO's Real-time Event Service is described in:
 *
 * http://doc.ece.uci.edu/~coryan/EC/
 *
 * @author Carlos O'Ryan <coryan@uci.edu>
 */

#ifndef TAO_RTEC_DEFAULTEVENTDATA_IDL
#define TAO_RTEC_DEFAULTEVENTDATA_IDL

#include <OctetSeq.pidl>

#pragma prefix ""

/// Define one of the common event payloads
typedef CORBA::OctetSeq EventPayload;

/**
 * @brief User defined Event Data
 *
 *
 * This structure defines the default payload in TAO's Real-time Event
 * Service.
 *
 * Users wanting maximum flexibility can use an Any, users that only
 * have one type of event may use structures, other users may preffer
 * union, trying to strike a balance between performance and
 * flexibility.  Users willing to implement their own marshalling may
 * use a sequence of octets.
 *
 * The Event Service is completely transparent as to the contents of
 * this structure.
 */
struct RtecEventData
{
#ifndef TAO_LACKS_EVENT_CHANNEL_OCTET_SEQUENCE
  /// Add padding to align the octet sequence contents
  /**
   * This fields ensures that the contents of the octet sequence
   * following are always aligned to an 8-byte boundary.
   * Such alignment allows application developers to implement custom
   * demarshaling from the octet sequence without requiring any data
   * copies.
   *
   * This is how this works:
   * - The last field in the header is an 8-byte unsigned long, hence
       the header finishes on an 8 byte boundary.
   *  - The pad1 long has 4 bytes.
   * - The length in the octet sequence adds another 4 bytes.
   * - Thus the data in the octet sequence starts on an 8 bytes
   *    boundary too.
   */
  long pad1;

  /// Octet sequence payload.
  /**
   * This is the payload used more often by high-performance
   * applications.
   */
  EventPayload payload;
#endif /* TAO_LACKS_EVENT_CHANNEL_OCTET_SEQUENCE */

#ifndef TAO_LACKS_EVENT_CHANNEL_ANY
  /// Use a CORBA any type as payload.
  any any_value;
#endif /* TAO_LACKS_EVENT_CHANNEL_ANY */
};

#pragma prefix ""

#endif /* TAO_RTEC_DEFAULTEVENTDATA_IDL */
