TAO/tests/POA/Loader/Servant_Locator.h

   1 //=============================================================================
   2 /**
   3  *  @file     Servant_Locator.h
   4  *
   5  *   Defines a ServantLocator class , used with a POA having
   6  *   a NON_RETAIN policy.
   7  *
   8  *  @author  Kirthika Parameswaran <kirthika@cs.wustl.edu>
   9  */
  10 //=============================================================================
  11
  12
  13 #ifndef SERVANT_LOCATOR_H
  14 #define SERVANT_LOCATOR_H
  15
  16 #include "tao/PortableServer/PortableServer.h"
  17 #include "tao/PortableServer/ServantLocatorC.h"
  18 #include "tao/LocalObject.h"
  19
  20 #include "tao/ORB.h"
  21
  22 #include "ace/DLL.h"
  23 #include "ace/SString.h"
  24 #include "ace/Log_Msg.h"
  25
  26 class ServantLocator :
  27   public virtual PortableServer::ServantLocator,
  28   public virtual ::CORBA::LocalObject
  29 {
  30   // = TITLE
  31   //   This class is used by a POA with USE_SERVANT_MANAGER and
  32   //   NON_RETAIN policy.
  33   //
  34   // = DESCRIPTION
  35   //   This class defines the Servant Locator interface of the Servant
  36   //   Manager. It is invoked when the POA has an USE_SERVANT_MANAGER
  37   //   policy and a servant_retention policy of NON_RETAIN type.
  38 public:
  39   /**
  40    * This typedef is used to typecast the void* obtained when finding
  41    * a symbol in the dll. Invoking the function pointer obtained would
  42    * get a servant.
  43    */
  44   typedef PortableServer::Servant
  45            (*SERVANT_FACTORY) (const PortableServer::ObjectId &oid,
  46                                PortableServer::POA_ptr poa,
  47                                CORBA::ORB_ptr orb);
  48
  49   /**
  50    * This typedef is used to obtain the garbage_collection_function symbol
  51    * in the dll. Invoking the function pointer obtained would then destroy
  52    * the servant.
  53    */
  54   typedef void
  55           (*SERVANT_GARBAGE_COLLECTOR) (const PortableServer::ObjectId &oid,
  56                                         PortableServer::POA_ptr,
  57                                         PortableServer::Servant servant);
  58
  59   /// Constructor.
  60   ServantLocator (CORBA::ORB_ptr orb,
  61                   const ACE_TCHAR *dllname,
  62                   const ACE_TCHAR *factory_function,
  63                   const ACE_TCHAR *garbage_collection_function);
  64
  65   /**
  66    * This method is invoked by a POA whenever it receives a request
  67    * for test object that is not currently active.  When the POA is
  68    * created using the NON_RETAIN policy the Active Object Map is not
  69    * maintained, in other words, an association between the ObjectId
  70    * and the servant is not maintained. Hence every client request the
  71    * servant has to be loaded. Note the operation argument. This
  72    * argument specifies the operation to be invoked on the
  73    * servant. The cookie helps in marking the servant. This marking is
  74    * useful while destroying the servant.
  75    */
  76   virtual PortableServer::Servant preinvoke (const PortableServer::ObjectId &oid,
  77                                              PortableServer::POA_ptr adapter,
  78                                              const char *operation,
  79                                              PortableServer::ServantLocator::Cookie &the_cookie);
  80
  81   /**
  82    * This method is invoked whenever a test servant completes a
  83    * request. As the Servant Loactor interface is used when the POA
  84    * doesnt maintain the Active Object Map, its necessary to get rid
  85    * of the servant after the client request has been processed. The
  86    * appropriate servant is destroyed by verifying the cookie.Again
  87    * this method is invoked per client request.
  88    */
  89   virtual void postinvoke (const PortableServer::ObjectId &oid,
  90                            PortableServer::POA_ptr adapter,
  91                            const char *operation,
  92                            PortableServer::ServantLocator::Cookie the_cookie,
  93                            PortableServer::Servant the_servant);
  94
  95 private:
  96   /// The name of the dll containing the servant.
  97   ACE_CString dllname_;
  98
  99   /// The symbol which on getting invoked will give us the servant
 100   /// pointer.
 101   ACE_CString create_symbol_;
 102
 103   /// The ACE_DLL object which performs the task of loading the dll
 104   /// and accessing it.
 105   ACE_DLL dll_;
 106
 107   /// The function pointer of factory_function type.
 108   SERVANT_FACTORY servant_supplier_;
 109
 110   /// The function pointer of garbage_collection_function type.
 111   SERVANT_GARBAGE_COLLECTOR servant_garbage_collector_;
 112
 113   /// A reference to the ORB.
 114   CORBA::ORB_var orb_;
 115 };
 116
 117 #endif /* SERVANT_LOCATOR_H */