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// -*- C++ -*-
// $Id$
// ============================================================================
//
// = LIBRARY
// AMI_Observer
//
// = FILENAME
// Callback_i.h
//
// = DESCRIPTION
// Header file for the Web_Server::Callback implementation.
//
// = AUTHOR
// Ossama Othman <ossama@uci.edu>
//
// ============================================================================
#ifndef CALLBACK_I_H
#define CALLBACK_I_H
#include "ace/FILE_Addr.h"
#include "ace/FILE_IO.h"
#include "Push_Web_ServerS.h"
#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */
// Implement the Web_Server::Callback interface.
class Callback_i :
public virtual POA_Web_Server::Callback
{
// = TITLE
// Implement the Web_Server::Callback interface.
//
// = DESCRIPTION
// A <Callback> object implements the Observer pattern. It
// simply "watches" while the Content Server pushes chunks of
// data to itself. Once the Content Server pushes the last chunk
// of data, the <Callback> object spawns an external viewer to
// display the pushed data based on the data content type
// returned by the Iterator_Factory::register_callback() method.
//
// Since the server pushes data to the <Callback> object
// asynchronously, and since instances of this <Callback> class
// are registered with the Content Server asynchronously, there
// is no guarantee that the metadata containing the content type
// will arrive before the content of the file. As such, this
// class atomically sets and checks the flags that provide the
// current condition of the metadata and content, in case two
// concurrently running threads attempt to update the state
// contained within a given <Callback> object.
friend class Callback_i_Friend;
// Dummy friend class declaration to quiet down a warning.
public:
Callback_i (int *request_count);
// Constructor
virtual void next_chunk (const Web_Server::Chunk_Type &chunk,
CORBA::Boolean last_chunk);
// This operation returns the next <chunk> of the file starting at
// <offset>. If there are no more bindings, false is returned.
void metadata (const Web_Server::Metadata_Type &metadata);
// Set metadata associated with received data.
private:
~Callback_i (void);
// Destructor must be private to ensure that this object is
// allocated on the heap.
int metadata_received (void);
// Returns one if the metadata was received, and zero otherwise.
int content_received (void);
// Returns one if the entire content was received, and zero
// otherwise.
int get_viewer (char *viewer, size_t length);
// Get the name of the viewer associated with the file being
// retrieved.
int spawn_viewer (void);
// Spawn an external view to display the retrieved file.
private:
void deactivate (void);
// Deactivate this Callback servant.
private:
ACE_FILE_Addr file_;
// The Addr corresponding to the retrieved file.
ACE_FILE_IO file_io_;
// The object that provides all file related IO operations
// (e.g. read, write, etc).
Web_Server::AMI_CallbackHandler_var ami_handler_;
// Reference to this Reply Handler's self.
Web_Server::Metadata_Type metadata_;
// The metadata associated with the file being retrieved from the
// web server.
int last_chunk_;
// Flag that indicates entire data content has been received.
TAO_SYNCH_MUTEX lock_;
// Lock used to prevent race conditions when checking to see if
// metadata or entire content has been received.
int *request_count_;
// Pointer to external status monitoring variable. The contents (not
// the pointer itself) of the <pending_data> parameter will be
// decremented when file retrieval has completed.
};
#endif /* CALLBACK_I_H */
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