path: root/ace/Asynch_IO.h

/* -*- C++ -*- */
// $Id: Asynch_IO.h,v

// ============================================================================
//
// = LIBRARY
//    ace
// 
// = FILENAME
//    Asynch_IO.h
//
// = AUTHOR
//    Irfan Pyarali (irfan@cs.wustl.edu)
//    Tim Harrison (harrison@cs.wustl.edu)
// 
// ============================================================================

#if !defined (ACE_ASYNCH_IO_H)
#define ACE_ASYNCH_IO_H

#include "ace/OS.h"

#if defined (ACE_WIN32)
// This only works on Win32 platforms. 
//
// 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

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

class ACE_Export ACE_Asynch_Result : protected 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.
{

  // Proactor is the only class which is allowed to call the
  // <complete> method.
  friend class ACE_Proactor;

public:
  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 

  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.
};

// ************************************************************

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.
{
protected:
  ACE_Asynch_Operation (void);
  // A do nothing constructor.
  
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.

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

    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. 
  {
    friend class ACE_Asynch_Write_Stream;
    // The factory has special privileges.

  public:
    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:
    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. 

    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:
    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
  //     
  // = TITLE
  //     
  //     This class is a factory for starting off asynchronous writes
  //     on a file.
  //
  // = DESCRIPTION
  //     
  //     Once <open> is called, multiple asynchronous <write>s can
  //     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.
{
public:
  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:
    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.

  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. 
  {
    friend class ACE_Asynch_Accept;
    // 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 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:
    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.
    
    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.
  };  
};

// ************************************************************

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. 
  {
    friend class ACE_Asynch_Transmit_File;
    // The factory has special privileges.
    
  public:
    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:
    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. 
    
    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. 

    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.

    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_notify (const ACE_Asynch_Notify::Result &result);
  */

  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.
{
  friend class ACE_Asynch_Acceptor<ACE_Service_Handler>;
  // The Acceptor is the factory and therefore should have special
  // privileges.

public:
  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) = 0;
  // <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 */
#endif /* ACE_ASYNCH_IO_H */