TAO/examples/Content_Server/AMI_Observer/Push_Iterator_Handler.h

   1 // -*- C++ -*-
   2
   3 //=============================================================================
   4 /**
   5  *  @file     Push_Iterator_Handler.h
   6  *
   7  *   Header file for the AMI_Iterator_FactoryHandler implementation.
   8  *
   9  *  @author  Ossama Othman <ossama@uci.edu>
  10  */
  11 //=============================================================================
  12
  13
  14 #ifndef PUSH_ITERATOR_HANDLER_H
  15 #define PUSH_ITERATOR_HANDLER_H
  16
  17 #include "Push_Web_ServerS.h"
  18
  19 #if !defined (ACE_LACKS_PRAGMA_ONCE)
  20 # pragma once
  21 #endif /* ACE_LACKS_PRAGMA_ONCE */
  22
  23 // Forward declaration
  24 class Callback_i;
  25
  26 class Push_Iterator_Handler
  27   : public virtual POA_Web_Server::AMI_Iterator_FactoryHandler
  28 {
  29   // = TITLE
  30   //    Implement the Web_Server::Iterator_Factory AMI Reply Handler.
  31   //
  32   // = DESCRIPTION
  33   //    This classes asynchronously registers a reference to the
  34   //    client-side <Callback> object in the Content Server.  Once
  35   //    registered, the <Callback> will begin receiving chunks of data
  36   //    pushed from the Content Server.
  37   //
  38   //    Since registration occurs asynchronously, it is possible that
  39   //    the metadata returned from the <Iterator_Factory> will be
  40   //    received after the content of the file has been received.  The
  41   //    <Callback> object is equipped to handle this possibility.
  42   //
  43   //    The register_callback() reply handler method in this class
  44   //    receives the metadata, and then passes it to the <Callback>
  45   //    object.  Once the metadata is received, there is no longer any
  46   //    use for this <Push_Iterator_Handler> object, and it is
  47   //    deactivated.
  48
  49   /// Dummy friend class declaration to quiet down a warning.
  50   friend class Push_Iterator_Handler_Friend;
  51
  52 public:
  53   /// Constructor that creates a content iterator corresponding to the
  54   /// name of the file being retrieved from the web server.
  55   Push_Iterator_Handler (void);
  56
  57   /**
  58    * Activate and run this Reply Handler.  The contents (not the
  59    * pointer itself) of the <request_count> parameter will be
  60    * incremented when file retrieval begins, and decremented when file
  61    * retrieval completes.
  62    */
  63   void run (int *request_count,
  64             const char *pathname,
  65             Web_Server::Iterator_Factory_ptr factory);
  66
  67 private:
  68
  69   /// Destructor  (private to ensure that Iterator_Handler is allocated
  70   /// on the heap).
  71   ~Push_Iterator_Handler (void);
  72
  73   /// AMI callback that is invoked when a response from the
  74   /// corresponding server method is received.
  75   virtual void register_callback
  76   (const Web_Server::Metadata_Type &metadata);
  77
  78   virtual void register_callback_excep
  79   (::Messaging::ExceptionHolder *)
  80     {}
  81
  82   /// Deactivate this handler.
  83   void deactivate (void);
  84
  85 private:
  86   /// The servant that accepts data pushed from the content server.
  87   Callback_i *callback_servant_;
  88
  89   /// Reference to the callback object the server sends data to.
  90   Web_Server::Callback_var callback_;
  91
  92   /// Reference to this Reply Handler's self.
  93   Web_Server::AMI_Iterator_FactoryHandler_var ami_handler_;
  94 };
  95
  96 #endif  /* PUSH_ITERATOR_HANDLER_H */