TAO/tests/POA/On_Demand_Loading/Servant_Locator.h

   1 //=============================================================================
   2 /**
   3  *  @file     Servant_Locator.h
   4  *
   5  *   Defines a ServantLocator_i class , used with a POA having
   6  *   a NON_RETAIN policy.
   7  *
   8  *  @author  Kirthika Parameswaran <kirthika@cs.wustl.edu>
   9  */
  10 //=============================================================================
  11
  12 #ifndef SERVANT_LOCATOR_H
  13 #define SERVANT_LOCATOR_H
  14
  15 #include "ace/DLL.h"
  16
  17 #include "Servant_Manager.h"
  18 #include "tao/PortableServer/ServantLocatorC.h"
  19 #include "tao/LocalObject.h"
  20
  21 class ServantLocator_i :
  22   public virtual PortableServer::ServantLocator,
  23   public virtual ::CORBA::LocalObject
  24
  25 {
  26   // = TITLE
  27   //   This class is used by a POA with USE_SERVANT_MANAGER and
  28   //   NON_RETAIN policy.
  29   //
  30   // = DESCRIPTION
  31   //   This class defines the Servant Locator interface of the Servant
  32   //   Manager. It is invoked when the POA has an USE_SERVANT_MANAGER
  33   //   policy and a servant_retention policy of NON_RETAIN type.
  34 public:
  35   /// Constructor.
  36   ServantLocator_i (CORBA::ORB_ptr orb);
  37
  38   /**
  39    * This method is invoked by a POA whenever it receives a request
  40    * for test object that is not currently active.  When the POA is
  41    * created using the NON_RETAIN policy the Active Object Map is not
  42    * maintained, in other words, an association between the ObjectId
  43    * and the servant is not maintained. Hence every client request the
  44    * servant has to be loaded. Note the operation argument. This
  45    * argument specifies the operation to be invoked on the
  46    * servant. The cookie helps in marking the servant. This marking is
  47    * useful while destroying the servant.
  48    */
  49   virtual PortableServer::Servant preinvoke (const PortableServer::ObjectId &oid,
  50                                              PortableServer::POA_ptr adapter,
  51                                              const char *operation,
  52                                              PortableServer::ServantLocator::Cookie &the_cookie);
  53
  54   /**
  55    * This method is invoked whenever a test servant completes a
  56    * request. As the Servant Loactor interface is used when the POA
  57    * doesnt maintain the Active Object Map, its necessary to get rid
  58    * of the servant after the client request has been processed. The
  59    * appropriate servant is destroyed by verifying the cookie.Again
  60    * this method is invoked per client request.
  61    */
  62   virtual void postinvoke (const PortableServer::ObjectId &oid,
  63                            PortableServer::POA_ptr adapter,
  64                            const char *operation,
  65                            PortableServer::ServantLocator::Cookie the_cookie,
  66                            PortableServer::Servant the_servant);
  67
  68   /// Returns an ObjectId when given an dll name and the factory method
  69   /// to be invoked in the dll.
  70   PortableServer::ObjectId_var create_dll_object_id (const char *dllname,
  71                                                      const char *factory_function);
  72 private:
  73   /**
  74    * The <ServantManager_i> object that provides utility methods.  The
  75    * methods include obtaining the servant using an ACE_DLL object,
  76    * destroying the servant and extracting the dllname and factory
  77    * function from the ObjectId.
  78    */
  79   ServantManager_i servant_manager_;
  80 };
  81
  82 #endif /* SERVANT_LOCATOR_H */