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// -*- C++ -*-
//=============================================================================
/**
* @file Pluggable_Messaging.h
*
* $Id$
*
* Interface for the TAO pluggable messaging framework.
*
*
* @author Balachandran Natarajan <bala@cs.wustl.edu>
*/
//=============================================================================
#ifndef TAO_PLUGGABLE_MESSAGING_H
#define TAO_PLUGGABLE_MESSAGING_H
#include /**/ "ace/pre.h"
#include "tao/TAO_Export.h"
#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */
#include "tao/Basic_Types.h"
namespace CORBA
{
class Exception;
}
class TAO_Target_Specification;
class TAO_Pluggable_Reply_Params;
class TAO_Pluggable_Reply_Params_Base;
class TAO_Transport;
class TAO_Operation_Details;
class TAO_Target_Specification;
class TAO_OutputCDR;
class TAO_Queued_Data;
class ACE_Time_Value;
// @@ The more I think I about this class, I feel that this class need
// not be a ABC as it is now. Instead we have these options
// (1) Parametrize this class with the "Messaging Object". Then the
// implementations can just redirect the request to the class
// that it has been specialised with
// (2) Use a bridge pattern here ie. the interface exposed by this
// class will redirect the request to the implementation which
// would be "right messaging" object.
// Both of them feasible. If we are not going like templates much, (2)
// is seems to be a better option.
// I am going to take a closer look on this after my MS defense -
// Bala
/**
* @class TAO_Pluggable_Messaging
*
* @brief Generic definitions Messaging class.
*
* This interface tries to define generic methods that could be
* different messaging protocols
*/
class TAO_Export TAO_Pluggable_Messaging
{
public:
/// Dtor
virtual ~TAO_Pluggable_Messaging (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) = 0;
/// 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) = 0;
/**
* Write the reply header
* The reply header is a part of any messaging protocol. The
* messaging protocol implementation would implement the way the
* reply header is written.
*/
virtual int generate_reply_header (
TAO_OutputCDR &cdr,
TAO_Pluggable_Reply_Params_Base ¶ms) = 0;
/**
* Write the locate reply header
* The locate reply header is a part of any messaging protocol. The
* messaging protocol implementation would implement the way the
* locate reply header is written.
*/
virtual int generate_locate_reply_header (
TAO_OutputCDR &cdr,
TAO_Pluggable_Reply_Params_Base ¶ms) = 0;
/**
* This method reads the message on the connection. Returns 0 when
* there is short read on the connection. Returns 1 when the full
* message is read and handled. Returns -1 on errors. If @a block is
* 1, then reply is read in a blocking manner.
*/
virtual int read_message (TAO_Transport *transport,
int block = 0,
ACE_Time_Value *max_wait_time = 0) = 0;
/// Format the message in the @a cdr. May not be needed in
/// general.
virtual int format_message (TAO_OutputCDR &cdr) = 0;
/// Do any initialisations that may be needed.
virtual void init (CORBA::Octet major,
CORBA::Octet minor) = 0;
/// Parse the incoming messages..
virtual int parse_incoming_messages (ACE_Message_Block &message_block) = 0;
/// Calculate the amount of data that is missing in the @a incoming
/// message block.
virtual ssize_t missing_data (ACE_Message_Block &incoming) = 0;
/// Get the details of the message parsed through the @a qd.
virtual void get_message_data (TAO_Queued_Data *qd) = 0;
/* Extract the details of the next message from the @a incoming
* through @a qd. Returns 1 if there are more messages and returns a
* 0 if there are no more messages in @a incoming.
*/
virtual int extract_next_message (ACE_Message_Block &incoming,
TAO_Queued_Data *&qd) = 0;
/// Check whether the node @a qd needs consolidation from @a incoming
virtual int consolidate_node (TAO_Queued_Data *qd,
ACE_Message_Block &incoming) = 0;
/// Parse the request message, make an upcall and send the reply back
/// to the "request initiator"
virtual int process_request_message (TAO_Transport *transport,
TAO_Queued_Data *qd) = 0;
/// 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) = 0;
/// Generate a reply message with the exception @a ex.
virtual int generate_exception_reply (
TAO_OutputCDR &cdr,
TAO_Pluggable_Reply_Params_Base ¶ms,
CORBA::Exception &ex) = 0;
/// Is the messaging object ready for processing BiDirectional
/// request/response?
virtual int is_ready_for_bidirectional (TAO_OutputCDR &msg) = 0;
/// Reset the messaging the object
virtual void reset (void) = 0;
/// Header length
virtual size_t header_length (void) const = 0;
/// Fragment header length
virtual size_t fragment_header_length (CORBA::Octet major,
CORBA::Octet minor) const = 0;
/// Accessor for the output CDR stream
virtual TAO_OutputCDR &out_stream (void) = 0;
};
#include /**/ "ace/post.h"
#endif /*TAO_PLUGGABLE_MESSAGING_H*/
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