GIOP_Message_Lite.h

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// -*- C++ -*-
//
// ===================================================================
/**
 *  @file GIOP_Message_Lite.h
 *
 *  GIOP_Message_Lite.h,v 1.44 2006/04/20 12:37:17 jwillemsen Exp
 *
 *  @author Balachandran Natarajan <bala@cs.wustl.edu>
 *  @author Carlos O'Ryan <coryan@uci.edu>
 */
// ===================================================================

#ifndef TAO_GIOP_MESSAGE_LITE_H
#define TAO_GIOP_MESSAGE_LITE_H

#include /**/ "ace/pre.h"

#include "tao/Pluggable_Messaging.h"

#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */

#include "tao/Pluggable_Messaging_Utils.h"
#include "tao/GIOP_Utils.h"
#include "tao/SystemException.h"
#include "tao/CDR.h"

TAO_BEGIN_VERSIONED_NAMESPACE_DECL

class TAO_Operation_Details;
class TAO_Pluggable_Reply_Params;
class TAO_GIOP_Locate_Request_Header;
class TAO_Queued_Data;
class TAO_ServerRequest;
class TAO_GIOP_Message_Version;

/**
 * @class TAO_GIOP_Message_Lite
 *
 * @brief Definitions of GIOPLite specific stuff
 *
 * This protocol is a modified version of GIOP. This is more suited
 * for homogenous platforms.
 */
class TAO_Export TAO_GIOP_Message_Lite : public TAO_Pluggable_Messaging
{
public:

  /// Constructor
  TAO_GIOP_Message_Lite (TAO_ORB_Core *orb_core,
                         size_t input_cdr_size = ACE_CDR::DEFAULT_BUFSIZE);

  /// Dtor
  virtual ~TAO_GIOP_Message_Lite (void);

  /// Initialize the object -- this is a dummy for GIOPlite
  virtual void init (CORBA::Octet, CORBA::Octet);

  /// Reset the messaging the object
  virtual void reset (void);

  /// Write the RequestHeader in to the @a cdr stream. The underlying
  /// implementation of the mesaging should do the right thing.
  virtual int generate_request_header (TAO_Operation_Details &op,
                                       TAO_Target_Specification &spec,
                                       TAO_OutputCDR &cdr);

  /// Write the RequestHeader in to the @a cdr stream.
  virtual int generate_locate_request_header (
      TAO_Operation_Details &op,
      TAO_Target_Specification &spec,
      TAO_OutputCDR &cdr);

  /// Write the reply header
  virtual int generate_reply_header (
      TAO_OutputCDR &cdr,
      TAO_Pluggable_Reply_Params_Base &params
    );

  virtual int generate_fragment_header (TAO_OutputCDR & cdr,
                                        CORBA::ULong request_id);

  /// Format the message. As we have not written the message length in
  /// the header, we make use of this oppurtunity to insert and format
  /// the message.
  virtual int format_message (TAO_OutputCDR &cdr);

private:
  /// Parse the incoming messages..
  ///
  /// \retval -1 There was some error parsing the GIOP header
  /// \retval 0  The GIOP header was parsed correctly
  /// \retval 1  There was not enough data in the message block to
  ///            parse the header
  int parse_incoming_messages (ACE_Message_Block &message_block);

  /// Get the message type. The return value would be one of the
  /// following:
  /// TAO_PLUGGABLE_MESSAGE_REQUEST,
  /// TAO_PLUGGABLE_MESSAGE_REPLY,
  /// TAO_PLUGGABLE_MESSAGE_CLOSECONNECTION,
  /// TAO_PLUGGABLE_MESSAGE_MESSAGE_ERROR.
  /// TAO_PLUGGABLE_MESSAGE_MESSAGE_CANCELREQUEST.
  TAO_Pluggable_Message_Type message_type (void) const;

public:
  /// Parse the details of the next message from the @a incoming
  /// and initializes attributes of @a qd. Returns 0 if the message
  /// header could not be parsed completely, returns a 1 if the message
  /// header could be parsed completely and returns -1 on error.
  virtual int parse_next_message (ACE_Message_Block &incoming,
                                  TAO_Queued_Data &qd,        /* out */
                                  size_t &mesg_length);      /* out */


  /// Extract the details of the next message from the @a incoming
  /// through @a qd. Returns 0 if the message header could not be
  /// parsed completely, returns a 1 if the message header could be
  /// parsed completely and returns -1 on error.
  virtual int extract_next_message (ACE_Message_Block &incoming,
                                    TAO_Queued_Data *&qd);

  /// Check whether the node @a qd needs consolidation from @a incoming
  virtual int consolidate_node (TAO_Queued_Data *qd,
                                ACE_Message_Block &incoming);

  /// Process the request message that we have received on the
  /// connection
  virtual int process_request_message (TAO_Transport *transport,
                                       TAO_Queued_Data *qd);

  /// Parse the reply message that we received and return the reply
  /// information through @a reply_info
  virtual int process_reply_message (
      TAO_Pluggable_Reply_Params &reply_info,
      TAO_Queued_Data *qd);

  /// Generate a reply message with the exception @a ex.
  virtual int generate_exception_reply (
      TAO_OutputCDR &cdr,
      TAO_Pluggable_Reply_Params_Base &params,
      CORBA::Exception &x
    );

  /// Consolidate fragmented message with associated fragments, being
  /// stored withi this class.  If reliable transport is used (like
  /// TCP) fragments are partialy ordered on stack, last fragment on
  /// top. Otherwise If un-reliable transport is used (like UDP)
  /// fragments may be dis-ordered, and must be ordered before
  /// consolidation.  @return 0 on success and @a msg points to
  /// consolidated message, 1 if there are still fragmens outstanding,
  /// in case of error -1 is being returned. In any case @a qd must be
  /// released by method implementation.
  virtual int consolidate_fragmented_message (TAO_Queued_Data *qd,
                                              TAO_Queued_Data *&msg);

  /// Discard all fragments associated to request-id encoded in
  /// cancel_request.  This operation will never be called
  /// concurrently by multiplpe threads nor concurrently to
  /// consolidate_fragmented_message @r 0 on success, 1 if no matching
  /// fragment chain exists, -1 on error
  virtual int discard_fragmented_message (const TAO_Queued_Data *cancel_request);

  /// Outgoing GIOP message fragmentation strategy.
  virtual TAO_GIOP_Fragmentation_Strategy * fragmentation_strategy (void);

private:

  /// Writes the GIOP header in to @a msg
  /// @note If the GIOP header happens to change in the future, we can
  /// push this method in to the generator_parser classes.
  int write_protocol_header (TAO_GIOP_Message_Type t,
                             TAO_OutputCDR &msg);

  /// Processes the GIOP_REQUEST messages
  int process_request (TAO_Transport *transport,
                       TAO_InputCDR &input,
                       TAO_OutputCDR &output);

  /// Processes the GIOP_LOCATE_REQUEST messages
  int process_locate_request (TAO_Transport *transport,
                              TAO_InputCDR &input,
                              TAO_OutputCDR &output);

  /// Make a GIOP_LOCATEREPLY and hand that over to the transport so
  /// that it can be sent over the connection.
  /// @note As on date 1.1 & 1.2 seem to have similar headers. Till an
  /// unmanageable difference comes let them be implemented here.
  int make_send_locate_reply (TAO_Transport *transport,
                              TAO_OutputCDR &output,
                              TAO_GIOP_Locate_Request_Header &request,
                              TAO_GIOP_Locate_Status_Msg &status);

  /// Send error messages
  int  send_error (TAO_Transport *transport);

  /// Close a connection, first sending GIOP::CloseConnection.
  void send_close_connection (const TAO_GIOP_Message_Version &version,
                              TAO_Transport *transport,
                              void *ctx);

  /// We must send a LocateReply through @a transport, this request
  /// resulted in some kind of exception.
  int send_reply_exception (TAO_Transport *transport,
                            TAO_ORB_Core* orb_core,
                            CORBA::ULong request_id,
                            IOP::ServiceContextList *svc_info,
                            CORBA::Exception *x);

  /// Print out a debug messages..
  void dump_msg (const char *label,
                 const u_char *ptr,
                 size_t len);

  TAO_Queued_Data *make_queued_data (size_t sz);

  /// Write the locate reply header
  virtual int generate_locate_reply_header (
      TAO_OutputCDR & /*cdr*/,
      TAO_Pluggable_Reply_Params_Base & /*params*/);

  /// Is the messaging object ready for processing BiDirectional
  /// request/response?
  virtual int is_ready_for_bidirectional (TAO_OutputCDR &msg);

  /// Header length
  virtual size_t header_length (void) const;

  /// Fragment header length
  virtual size_t fragment_header_length (CORBA::Octet major,
                                         CORBA::Octet minor) const;

  virtual TAO_OutputCDR &out_stream (void);

private:

  /// Write the request header in to <msg>
  int write_request_header (
      const TAO_Operation_Details &opdetails,
      TAO_Target_Specification &spec,
      TAO_OutputCDR &msg);

  /// Write the LocateRequest header
  int write_locate_request_header (
      CORBA::ULong request_id,
      TAO_Target_Specification &spec,
      TAO_OutputCDR &msg);

  /// Write the reply header in to <output>
  int write_reply_header (
      TAO_OutputCDR &output,
      TAO_Pluggable_Reply_Params_Base &reply
      ACE_ENV_ARG_DECL_WITH_DEFAULTS)
    ACE_THROW_SPEC ((CORBA::SystemException));

  /// Writes the locate _reply message in to the <output>
  int write_locate_reply_mesg (
      TAO_OutputCDR &output,
      CORBA::ULong request_id,
      TAO_GIOP_Locate_Status_Msg &status);

  /// Parse the Request Header from the incoming stream. This will do a
  /// version specific parsing of the incoming Request header
  int parse_request_header (TAO_ServerRequest &);

  /// Parse the Loacte Request Header from the incoming stream. This will do a
  /// version specific parsing of the incoming Request header
  int parse_locate_header (
      TAO_GIOP_Locate_Request_Header &);

  /// Parse the reply message
  int parse_reply (TAO_InputCDR &input,
                   TAO_Pluggable_Reply_Params &params);

  /// Parse the locate reply message from the server
  int parse_locate_reply (TAO_InputCDR &input,
                          TAO_Pluggable_Reply_Params &params);

  /// Initialize the relevant portions of a TAO_Queued_Data
  void init_queued_data (TAO_Queued_Data* qd) const;

private:

  /// Our copy of the ORB core...
  TAO_ORB_Core *orb_core_;

  /// The message type that we are going to process..
  CORBA::Octet message_type_;

  /// The pay load size
  CORBA::ULong message_size_;

  /// The byte order..
  /// @note GIOP lite cannot work between heterogenous platforms..
  CORBA::Octet byte_order_;

  TAO_OutputCDR cdr_;
};

TAO_END_VERSIONED_NAMESPACE_DECL

#include /**/ "ace/post.h"
#endif /*TAO_GIOP_MESSAGE_LITE_H*/

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