/* -*- C++ -*- */
// $Id$

// ============================================================================
//
// = LIBRARY
//    ace
//
// = FILENAME
//    Asynch_IO.h
//
// = DESCRIPTION
//    This only works on Win32 platforms or on POSIX platforms with
//    aio_ routines.
//
//    The implementation of <ACE_Asynch_Transmit_File> and
//    <ACE_Asynch_Accept> are only supported if ACE_HAS_WINSOCK2 is
//    defined or you are on WinNT 4.0 or higher.
//
// = AUTHOR
//    Irfan Pyarali (irfan@cs.wustl.edu),
//    Tim Harrison (harrison@cs.wustl.edu) and
//    Alexander Babu Arulanthu <alex@cs.wustl.edu> 
//
// ============================================================================

#if !defined (ACE_ASYNCH_IO_H)
#define ACE_ASYNCH_IO_H

#include "ace/OS.h"

#if (defined (ACE_WIN32) && !defined (ACE_HAS_WINCE)) || \
 (defined (ACE_HAS_AIO_CALLS))

#include "ace/Task.h"
#include "ace/Reactor.h"

// Forward declarations
class ACE_Proactor;
class ACE_Handler;
class ACE_Message_Block;
class ACE_INET_Addr;

class ACE_Export ACE_Asynch_Result : public ACE_OVERLAPPED
{
  // = TITLE
  //     An abstract class which adds information to the OVERLAPPED
  //     structure to make it more useful.
  //
  // = DESCRIPTION
  //     An abstract base class from which you can obtain some basic
  //     information like the number of bytes transferred, the ACT
  //     associated with the asynchronous operation, indication of
  //     success or failure, etc.  Subclasses may want to store more
  //     information that is particular to the asynchronous operation
  //     it represents.
public:
  // Proactor is the only class which is allowed to call the
  // <complete> method.
  friend class ACE_Proactor;

  u_long bytes_transferred (void) const;
  // Number of bytes transferred by the operation.

  const void *act (void) const;
  // ACT associated with the operation.

  int success (void) const;
  // Did the operation succeed?

  const void *completion_key (void) const;
  // This returns the ACT associated with the handle when it was
  // registered with the I/O completion port.  This ACT is not the
  // same as the ACT associated with the asynchronous operation.

  u_long error (void) const;
  // Error value if the operation fail.

  ACE_HANDLE event (void) const;
  // Event associated with the OVERLAPPED structure

  u_long offset (void) const;
  u_long offset_high (void) const;
  // Offset associated with the OVERLAPPED structure.  This really
  // make sense only when doing file I/O.

  ACE_Asynch_Result (ACE_Handler &handler,
		     const void* act,
		     ACE_HANDLE event,
		     u_long offset = 0,
		     u_long offset_high = 0);
  // Constructor.

#if defined (ACE_HAS_AIO_CALLS)
  aiocb* aiocb_ptr (void);
  // Returns the underlying <aio control block> used to issue the aio 
  // call. 
#endif /* ACE_HAS_AIO_CALLS */

  virtual ~ACE_Asynch_Result (void);
  // Destructor.

protected:
  virtual void complete (u_long bytes_transferred,
			 int success,
			 const void *completion_key,
			 u_long error = 0) = 0;
  // This is the key method.  Subclasses will override this method to
  // call the correct callback on the handler.

  ACE_Handler &handler_;
  // Handler that will be called back.

  const void *act_;
  // ACT for this operation.

  u_long bytes_transferred_;
  // Bytes transferred by this operation.

  int success_;
  // Success indicator.

  const void *completion_key_;
  // ACT associated with handle.

  u_long error_;
  // Error if operation failed.
  
#if defined (ACE_HAS_AIO_CALLS)
  aiocb *aiocb_ptr_;
  // This is the <aio control block> used to issue the <aio_>
  // call. Let us give this to the OS along with the result, so that
  // on completion we can take this and use it for <aio_error> and
  // <aio_return>. 
#endif /* ACE_HAS_AIO_CALLS */
};

class ACE_Export ACE_Asynch_Operation
{
  // = TITLE
  //     This is a base class for all asynch operations.
  //
  // = DESCRIPTION
  //     There are some attributes and functionality which is common
  //     to all asychronous operations.  This abstract class will
  //     factor out this code.
public:
  int open (ACE_Handler &handler,
	    ACE_HANDLE handle = ACE_INVALID_HANDLE,
	    const void *completion_key = 0,
	    ACE_Proactor *proactor = 0);
  // Initializes the factory with information which will be used with
  // each asynchronous call.  If (<handle> == ACE_INVALID_HANDLE),
  // <ACE_Handler::handle> will be called on the <handler> to get the
  // correct handle.

  int cancel (void);
  // This cancels all pending accepts operations that were issued by
  // the calling thread.  The function does not cancel asynchronous
  // operations issued by other threads.

  // Access methods.
  ACE_Proactor* proactor (void);
  // Return the underlying proactor.
protected:
#if defined (ACE_HAS_AIO_CALLS)
  int register_aio_with_proactor (aiocb *aiocb_ptr);
  // This call is for the POSIX implementation. This method is used by
  // <ACE_Asynch_Operation> to store some information with the
  // Proactor after an <aio_> call is issued, so that the Proactor can
  // retrive this information to do <aio_return> and <aio_error>.
  // Passing a '0' ptr returns the status, indicating whether there
  // are slots available or no. Passing a valid ptr stores the ptr
  // with the Proactor.
#endif /* ACE_HAS_AIO_CALLS */

  ACE_Asynch_Operation (void);
  // A no-op constructor.

  ACE_Proactor *proactor_;
  // Proactor that this Asynch IO will be registered with.

  ACE_Handler *handler_;
  // Handler that will receive the callback.

  ACE_HANDLE handle_;
  // I/O handle used for reading.
};

class ACE_Export ACE_Asynch_Read_Stream : public ACE_Asynch_Operation
{
  // = TITLE
  //     This class is a factory for starting off asynchronous reads
  //     on a stream.
  //
  // = DESCRIPTION
  //     Once <open> is called, multiple asynchronous <read>s can
  //     started using this class.  An ACE_Asynch_Read_Stream::Result
  //     will be passed back to the <handler> when the asynchronous
  //     reads completes through the <ACE_Handler::handle_read_stream>
  //     callback.
public:
  class Result;
  // Forward declaration of the Result class.

  ACE_Asynch_Read_Stream (void);
  // A do nothing constructor.

  int read (ACE_Message_Block &message_block,
	    u_long bytes_to_read,
	    const void *act = 0);
  // This starts off an asynchronous read.  Upto <bytes_to_read> will
  // be read and stored in the <message_block>.
  
protected:
  int shared_read (Result *result);
  // This is the method which does the real work and is there so that
  // the ACE_Asynch_Read_File class can use it too.

public:
  class ACE_Export Result : public ACE_Asynch_Result
  {
    // = TITLE
    //     This is that class which will be passed back to the
    //     <handler> when the asynchronous read completes.
    //
    // = DESCRIPTION
    //     This class has all the information necessary for the
    //     <handler> to uniquiely identify the completion of the
    //     asynchronous read.
    friend class ACE_Asynch_Read_Stream;
    // The factory has special privileges.

  public:
    u_long bytes_to_read (void) const;
    // The number of bytes which were requested at the start of the
    // asynchronous read.

    ACE_Message_Block &message_block (void) const;
    // Message block which contains the read data.

    ACE_HANDLE handle (void) const;
    // I/O handle used for reading.

    // protected:
    //
    // These two should really be protected.  But sometimes it
    // simplifies code to be able to "fake" a result.  Use carefully.
    Result (ACE_Handler &handler,
	    ACE_HANDLE handle,
	    ACE_Message_Block &message_block,
	    u_long bytes_to_read,
	    const void* act,
	    ACE_HANDLE event);
    // Constructor is protected since creation is limited to
    // ACE_Asynch_Read_Stream factory.

    virtual void complete (u_long bytes_transferred,
			   int success,
			   const void *completion_key,
			   u_long error = 0);
    // ACE_Proactor will call this method when the read completes.

  protected:
    u_long bytes_to_read_;
    // Bytes requested when the asynchronous read was initiated.

    ACE_Message_Block &message_block_;
    // Message block for reading the data into.

    ACE_HANDLE handle_;
    // I/O handle used for reading.
  };
};

class ACE_Export ACE_Asynch_Write_Stream : public ACE_Asynch_Operation
{
  // = TITLE
  //     This class is a factory for starting off asynchronous writes
  //     on a stream.
  //
  // = DESCRIPTION
  //     Once <open> is called, multiple asynchronous <writes>s can
  //     started using this class.  A ACE_Asynch_Write_Stream::Result
  //     will be passed back to the <handler> when the asynchronous
  //     write completes through the
  //     <ACE_Handler::handle_write_stream> callback.
public:
  class Result;
  // Forward declaration of the Result class.

  ACE_Asynch_Write_Stream (void);
  // A do nothing constructor.

  int write (ACE_Message_Block &message_block,
	     u_long bytes_to_write,
	     const void *act = 0);
  // This starts off an asynchronous write.  Upto <bytes_to_write>
  // will be written from the <message_block>.
  
protected:
  int shared_write (Result *result);
  // This is the method which does the real work and is there so that
  // the ACE_Asynch_Write_File class can use it too.

public:
  class ACE_Export Result : public ACE_Asynch_Result
  {
    // = TITLE
    //     This is that class which will be passed back to the
    //     <handler> when the asynchronous write completes.
    //
    // = DESCRIPTION
    //     This class has all the information necessary for the
    //     <handler> to uniquiely identify the completion of the
    //     asynchronous write.
  public:
    friend class ACE_Asynch_Write_Stream;
    // The factory has special privileges.

    u_long bytes_to_write (void) const;
    // The number of bytes which were requested at the start of the
    // asynchronous write.

    ACE_Message_Block &message_block (void) const;
    // Message block that contains the data to be written.

    ACE_HANDLE handle (void) const;
    // I/O handle used for writing.

    // protected:
    //
    // These two should really be protected.  But sometimes it
    // simplifies code to be able to "fake" a result.  Use carefully.
    Result (ACE_Handler &handler,
	    ACE_HANDLE handle,
	    ACE_Message_Block &message_block,
	    u_long bytes_to_write,
	    const void* act,
	    ACE_HANDLE event);
    // Constructor is protected since creation is limited to
    // ACE_Asynch_Write_Stream factory.

    virtual void complete (u_long bytes_transferred,
			   int success,
			   const void *completion_key,
			   u_long error = 0);
    // ACE_Proactor will call this method when the write completes.

  protected:
    u_long bytes_to_write_;
    // The number of bytes which were requested at the start of the
    // asynchronous write.

    ACE_Message_Block &message_block_;
    // Message block that contains the data to be written.

    ACE_HANDLE handle_;
    // I/O handle used for writing.
  };
};

class ACE_Export ACE_Asynch_Read_File : public ACE_Asynch_Read_Stream
{
  // = TITLE
  //     This class is a factory for starting off asynchronous reads
  //     on a file.
  //
  // = DESCRIPTION
  //     Once <open> is called, multiple asynchronous <read>s can
  //     started using this class.  A ACE_Asynch_Read_File::Result
  //     will be passed back to the <handler> when the asynchronous
  //     reads completes through the <ACE_Handler::handle_read_file>
  //     callback.
  //
  //     This class differs slightly from ACE_Asynch_Read_Stream as it
  //     allows the user to specify an offset for the read.
public:
  int read (ACE_Message_Block &message_block,
	    u_long bytes_to_read,
	    u_long offset = 0,
	    u_long offset_high = 0,
	    const void *act = 0);
  // This starts off an asynchronous read.  Upto <bytes_to_read> will
  // be read and stored in the <message_block>.  The read will start
  // at <offset> from the beginning of the file.
public:
  class ACE_Export Result : public ACE_Asynch_Read_Stream::Result
  {
    // = TITLE
    //     This is that class which will be passed back to the
    //     <handler> when the asynchronous read completes.
    //
    // = DESCRIPTION
    //     This class has all the information necessary for the
    //     <handler> to uniquiely identify the completion of the
    //     asynchronous read.
    //
    //     This class differs slightly from
    //     ACE_Asynch_Read_Stream::Result as it calls back
    //     <ACE_Handler::handle_read_file> on the <handler> instead of
    //     <ACE_Handler::handle_read_stream>.  No additional state is
    //     required by this class as ACE_Asynch_Result can store the
    //     <offset>.

    friend class ACE_Asynch_Read_File;
    // The factory has special privileges.

    // protected:
    //
    // These two should really be protected.  But sometimes it
    // simplifies code to be able to "fake" a result.  Use carefully.
    Result (ACE_Handler &handler,
	    ACE_HANDLE handle,
	    ACE_Message_Block &message_block,
	    u_long bytes_to_read,
	    const void* act,
	    u_long offset,
	    u_long offset_high,
	    ACE_HANDLE event);
    // Constructor is protected since creation is limited to
    // ACE_Asynch_Read_File factory.

    virtual void complete (u_long bytes_transferred,
			   int success,
			   const void *completion_key,
			   u_long error = 0);
    // ACE_Proactor will call this method when the read completes.
  };
};

class ACE_Export ACE_Asynch_Write_File : public ACE_Asynch_Write_Stream
{
public:
  // = TITLE
  //     This class is a factory for starting off asynchronous writes
  //     on a file.
  //
  // = DESCRIPTION
  //     Once <open> is called, multiple asynchronous <write>s can be
  //     started using this class.  A ACE_Asynch_Write_File::Result
  //     will be passed back to the <handler> when the asynchronous
  //     writes completes through the <ACE_Handler::handle_write_file>
  //     callback.
  //
  //     This class differs slightly from ACE_Asynch_Write_Stream as
  //     it allows the user to specify an offset for the write.
  int write (ACE_Message_Block &message_block,
	     u_long bytes_to_write,
	     u_long offset = 0,
	     u_long offset_high = 0,
	     const void *act = 0);
  // This starts off an asynchronous write.  Upto <bytes_to_write>
  // will be write and stored in the <message_block>.  The write will
  // start at <offset> from the beginning of the file.

public:
  class ACE_Export Result : public ACE_Asynch_Write_Stream::Result
  {
    // = TITLE
    //     This is that class which will be passed back to the
    //     <handler> when the asynchronous write completes.
    //
    // = DESCRIPTION
    //     This class has all the information necessary for the
    //     <handler> to uniquiely identify the completion of the
    //     asynchronous write.
    //
    //     This class differs slightly from
    //     ACE_Asynch_Write_Stream::Result as it calls back
    //     <ACE_Handler::handle_write_file> on the <handler> instead
    //     of <ACE_Handler::handle_write_stream>.  No additional state
    //     is required by this class as ACE_Asynch_Result can store
    //     the <offset>.

    friend class ACE_Asynch_Write_File;
    // The factory has special privileges.

    // protected:
    //
    // These two should really be protected.  But sometimes it
    // simplifies code to be able to "fake" a result.  Use carefully.
    Result (ACE_Handler &handler,
	    ACE_HANDLE handle,
	    ACE_Message_Block &message_block,
	    u_long bytes_to_write,
	    const void* act,
	    u_long offset,
	    u_long offset_high,
	    ACE_HANDLE event);
    // Constructor is protected since creation is limited to
    // ACE_Asynch_Write_File factory.

    virtual void complete (u_long bytes_transferred,
			   int success,
			   const void *completion_key,
			   u_long error = 0);
    // ACE_Proactor will call this method when the write completes.
  };
};

class ACE_Export ACE_Asynch_Accept : public ACE_Asynch_Operation
{
  // = TITLE
  //     This class is a factory for starting off asynchronous accepts
  //     on a listen handle.
  //
  // = DESCRIPTION
  //     Once <open> is called, multiple asynchronous <accept>s can
  //     started using this class.  A ACE_Asynch_Accept::Result will
  //     be passed back to the <handler> when the asynchronous accept
  //     completes through the <ACE_Handler::handle_accept>
  //     callback.
public:
  ACE_Asynch_Accept (void);
  // A do nothing constructor.

#if defined (ACE_HAS_AIO_CALLS)
  int open (ACE_Handler &handler,
	    ACE_HANDLE handle = ACE_INVALID_HANDLE,
	    const void *completion_key = 0,
	    ACE_Proactor *proactor = 0);
  // (We will also call base class's <open> from here).
#endif /* ACE_HAS_AIO_CALLS */

  int accept (ACE_Message_Block &message_block,
	      u_long bytes_to_read,
	      ACE_HANDLE accept_handle = ACE_INVALID_HANDLE,
	      const void *act = 0);
  // This starts off an asynchronous accept.  The asynchronous accept
  // call also allows any initial data to be returned to the
  // <handler>.  Upto <bytes_to_read> will be read and stored in the
  // <message_block>.  The <accept_handle> will be used for the
  // <accept> call.  If (<accept_handle> == INVALID_HANDLE), a new
  // handle will be created.
  //
  // <message_block> must be specified. This is because the address of
  // the new connection is placed at the end of this buffer.

public:
  class ACE_Export Result : public ACE_Asynch_Result
  {
    // = TITLE
    //     This is that class which will be passed back to the
    //     <handler> when the asynchronous accept completes.
    //
    // = DESCRIPTION
    //     This class has all the information necessary for the
    //     <handler> to uniquiely identify the completion of the
    //     asynchronous accept.
  public:
    friend class ACE_Asynch_Accept;
    // The factory has special privileges.

#if defined (ACE_HAS_AIO_CALLS)
    friend class ACE_Asynch_Accept_Handler;
    // This factory does it all, so it needs spl privileges. 
#endif /* ACE_HAS_AIO_CALLS */

    u_long bytes_to_read (void) const;
    // The number of bytes which were requested at the start of the
    // asynchronous accept.

    ACE_Message_Block &message_block (void) const;
    // Message block which contains the read data.

    ACE_HANDLE listen_handle (void) const;
    // I/O handle used for accepting new connections.

    ACE_HANDLE accept_handle (void) const;
    // I/O handle for the new connection.

    // protected:
    //
    // These two should really be protected.  But sometimes it
    // simplifies code to be able to "fake" a result.  Use carefully.
    Result (ACE_Handler &handler,
	    ACE_HANDLE listen_handle,
	    ACE_HANDLE accept_handle,
	    ACE_Message_Block &message_block,
	    u_long bytes_to_read,
	    const void* act,
	    ACE_HANDLE event);
    // Constructor is protected since creation is limited to
    // ACE_Asynch_Accept factory.

    virtual void complete (u_long bytes_transferred,
			   int success,
			   const void *completion_key,
			   u_long error = 0);
    // ACE_Proactor will call this method when the accept completes.

  protected:
    u_long bytes_to_read_;
    // Bytes requested when the asynchronous read was initiated.

    ACE_Message_Block &message_block_;
    // Message block for reading the data into.

    ACE_HANDLE listen_handle_;
    // I/O handle used for accepting new connections.

    ACE_HANDLE accept_handle_;
    // I/O handle for the new connection.
  };

private:
#if defined (ACE_HAS_AIO_CALLS)
  static void* thread_function  (void* reactor);
  // The thread function that does handle events 

  ACE_Reactor reactor_;
  // Reactor to wait on the <listen_handle>.

  ACE_Asynch_Accept_Handler* accept_handler_;
  // The Event Handler to do handle_input.
#endif /* ACE_HAS_AIO_CALLS */
};

class ACE_Export ACE_Asynch_Transmit_File : public ACE_Asynch_Operation
{
  // = TITLE
  //     This class is a factory for starting off asynchronous
  //     transmit files on a stream.
  //
  // = DESCRIPTION
  //     Once <open> is called, multiple asynchronous <transmit_file>s
  //     can started using this class.  A
  //     ACE_Asynch_Transmit_File::Result will be passed back to the
  //     <handler> when the asynchronous transmit file completes
  //     through the <ACE_Handler::handle_transmit_file> callback.
  //
  //     The transmit_file function transmits file data over a
  //     connected network connection. The function uses the operating
  //     system's cache manager to retrieve the file data. This
  //     function provides high-performance file data transfer over
  //     network connections.  This function would be of great use in
  //     a Web Server, Image Server, etc.
public:
  class Header_And_Trailer;
  // Forward declaration.

  ACE_Asynch_Transmit_File (void);
  // A "do-nothing" constructor.

  int transmit_file (ACE_HANDLE file,
		     Header_And_Trailer *header_and_trailer = 0,
		     u_long bytes_to_write = 0,
		     u_long offset = 0,
		     u_long offset_high = 0,
		     u_long bytes_per_send = 0,
		     u_long flags = 0,
		     const void *act = 0);
  // This starts off an asynchronous transmit file.  The <file> is a
  // handle to an open file.  <header_and_trailer> is a pointer to a
  // data structure that contains pointers to data to send before and
  // after the file data is sent.  Set this parameter to 0 if you only
  // want to transmit the file data.  Upto <bytes_to_write> will be
  // written to the <socket>.  If you want to send the entire file,
  // let <bytes_to_write> = 0.  <bytes_per_send> is the size of each
  // block of data sent per send operation.  Please read the Win32
  // documentation on what the flags should be.

public:
  class ACE_Export Result : public ACE_Asynch_Result
  {
    // = TITLE
    //     This is that class which will be passed back to the
    //     <handler> when the asynchronous transmit file completes.
    //
    // = DESCRIPTION
    //     This class has all the information necessary for the
    //     <handler> to uniquiely identify the completion of the
    //     asynchronous transmit file.
  public:
    friend class ACE_Asynch_Transmit_File;
    // The factory has special privileges.

    ACE_HANDLE socket (void) const;
    // Socket used for transmitting the file.

    ACE_HANDLE file (void) const;
    // File from which the data is read.

    Header_And_Trailer *header_and_trailer (void) const;
    // Header and trailer data associated with this transmit file.

    u_long bytes_to_write (void) const;
    // The number of bytes which were requested at the start of the
    // asynchronous transmit file.

    u_long bytes_per_send (void) const;
    // Number of bytes per send requested at the start of the transmit
    // file.

    u_long flags (void) const;
    // Flags which were passed into transmit file.

    // protected:
    //
    // These two should really be protected.  But sometimes it
    // simplifies code to be able to "fake" a result.  Use carefully.
    Result (ACE_Handler &handler,
	    ACE_HANDLE socket,
	    ACE_HANDLE file,
	    Header_And_Trailer *header_and_trailer,
	    u_long bytes_to_write,
	    u_long offset,
	    u_long offset_high,
	    u_long bytes_per_send,
	    u_long flags,
	    const void *act,
	    ACE_HANDLE event);
    // Constructor is protected since creation is limited to
    // ACE_Asynch_Transmit_File factory.

    virtual void complete (u_long bytes_transferred,
			   int success,
			   const void *completion_key,
			   u_long error = 0);
    // ACE_Proactor will call this method when the write completes.

  protected:
    ACE_HANDLE socket_;
    // Network I/O handle.

    ACE_HANDLE file_;
    // File I/O handle.

    Header_And_Trailer *header_and_trailer_;
    // Header and trailer data associated with this transmit file.

    u_long bytes_to_write_;
    // The number of bytes which were requested at the start of the
    // asynchronous transmit file.

    u_long bytes_per_send_;
    // Number of bytes per send requested at the start of the transmit
    // file.

    u_long flags_;
    // Flags which were passed into transmit file.
  };

  class ACE_Export Header_And_Trailer
  {
    // = TITLE
    //     The class defines a data structure that contains pointers
    //     to data to send before and after the file data is sent.
    //
    // = DESCRIPTION
    //     This class provides a wrapper over TRANSMIT_FILE_BUFFERS
    //     and provided a consistent use of ACE_Message_Blocks.
  public:
    Header_And_Trailer (ACE_Message_Block *header = 0,
			u_long header_bytes = 0,
			ACE_Message_Block *trailer = 0,
			u_long trailer_bytes = 0);
    // Constructor.

    void header_and_trailer (ACE_Message_Block *header = 0,
			     u_long header_bytes = 0,
			     ACE_Message_Block *trailer = 0,
			     u_long trailer_bytes = 0);
    // This method allows all the member to be set in one fell swoop.

    ACE_Message_Block *header (void) const;
    void header (ACE_Message_Block *message_block);
    // Header which goes before the file data.

    u_long header_bytes (void) const;
    void header_bytes (u_long bytes);
    // Size of the header data.

    ACE_Message_Block *trailer (void) const;
    void trailer (ACE_Message_Block *message_block);
    // Trailer which goes after the file data.

    u_long trailer_bytes (void) const;
    void trailer_bytes (u_long bytes);
    // Size of the trailer data.

    ACE_LPTRANSMIT_FILE_BUFFERS transmit_buffers (void);
    // Conversion routine.

  protected:
    ACE_Message_Block *header_;
    // Header data.

    u_long header_bytes_;
    // Size of header data.
    
    ACE_Message_Block *trailer_;
    // Trailer data.

    u_long trailer_bytes_;
    // Size of trailer data.

    ACE_TRANSMIT_FILE_BUFFERS transmit_buffers_;
    // Target data structure.
  };
};

class ACE_Export ACE_Handler
{
  // = TITLE
  //     This base class defines the interface for receiving the
  //     results of asynchronous operations.
  //
  // = DESCRIPTION
  //     Subclasses of this class will fill in appropriate methods.
public:
  ACE_Handler (void);
  // A do nothing constructor.

  ACE_Handler (ACE_Proactor *p);
  // A do nothing constructor which allows proactor to be set to <d>.

  virtual ~ACE_Handler (void);
  // Virtual destruction.

  virtual void handle_read_stream (const ACE_Asynch_Read_Stream::Result &result);
   // This method will be called when an asynchronous read completes on
  // a stream.

  virtual void handle_write_stream (const ACE_Asynch_Write_Stream::Result &result);
  // This method will be called when an asynchronous write completes
  // on a strea_m.

  virtual void handle_read_file (const ACE_Asynch_Read_File::Result &result);
  // This method will be called when an asynchronous read completes on
  // a file.

  virtual void handle_write_file (const ACE_Asynch_Write_File::Result &result);
  // This method will be called when an asynchronous write completes
  // on a file.

  virtual void handle_accept (const ACE_Asynch_Accept::Result &result);
  // This method will be called when an asynchronous accept completes.

  virtual void handle_transmit_file (const ACE_Asynch_Transmit_File::Result &result);
  // This method will be called when an asynchronous transmit file
  // completes.

  virtual void handle_time_out (const ACE_Time_Value &tv,
				const void *act = 0);
  // Called when timer expires.  <tv> was the requested time value and
  // <act> is the ACT passed when scheduling the timer

  ACE_Proactor *proactor (void);
  // Get the proactor associated with this handler.

  void proactor (ACE_Proactor *p);
  // Set the proactor.

  virtual ACE_HANDLE handle (void) const;
  // Get the I/O handle used by this <handler>. This method will be
  // called by the ACE_Asynch_* classes when an ACE_INVALID_HANDLE is
  // passed to <open>.
protected:
  ACE_Proactor *proactor_;
  // The proactor associated with this handler.
};

// Forward declartion
template <class HANDLER>
class ACE_Asynch_Acceptor;

class ACE_Export ACE_Service_Handler : public ACE_Handler
{
  // = TITLE
  //     This base class defines the interface for the
  //     ACE_Asynch_Acceptor to call into when new connection are
  //     accepted.
  //
  // = DESCRIPTION
  //     Subclasses of this class will fill in appropriate methods to
  //     define application specific behavior.
public:
  friend class ACE_Asynch_Acceptor<ACE_Service_Handler>;
  // The Acceptor is the factory and therefore should have special
  // privileges.

  ACE_Service_Handler (void);
  // A do nothing constructor.

  virtual ~ACE_Service_Handler (void);
  // Virtual destruction.

  virtual void open (ACE_HANDLE new_handle,
                     ACE_Message_Block &message_block);
  // <open> is called by ACE_Asynch_Acceptor to initialize a new
  // instance of ACE_Service_Handler that has been created after the a
  // new connection is accepted. The handle for the new connection is
  // passed along with an initial data that may have shown up.

  // protected:
  // This should be corrected after the correct semantics of the
  // friend has been figured out.

  virtual void addresses (const ACE_INET_Addr &remote_address,
			  const ACE_INET_Addr &local_address);
  // Called by ACE_Asynch_Acceptor to pass the addresses of the new
  // connections.
};

#if defined (__ACE_INLINE__)
#include "ace/Asynch_IO.i"
#endif /* __ACE_INLINE__ */

#endif /* ACE_WIN32 || ACE_HAS_AIO_CALLS*/
#endif /* ACE_ASYNCH_IO_H */