LookupService_Impl.h

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#include "Event_Handler.h"
#include "Reactor.h"

class LookupService_Impl : 
  public POA_LookupService, Event_Handler {
public:
  LookupService_Impl () {};
  ~LookupService_Impl () {};
  
  Lease_ptr bind (const CosNaming::Name &name,
                  CORBA::Object_ptr object,
                  TimeBase::TimeT duration,
                  LeaseHolder_ptr lease_holder)
    throw (InvalidDuration)
  {
    if (this->duration_is_acceptable (duration)) 
      {
        // Create a new lease
        Lease_Impl *lease_impl = 
          new Lease_Impl (current_time () + duration, 
                          this->_this(), name, lease_holder);
        
        // Get the CORBA object reference
        Lease_var lease = lease_impl->_this ();
        
        reactor_->register_timer (duration, 
                                  this,
                                  lease);
        
        // Delegate binding to actual Naming Service
        name_service_->bind (name, object);
        
        return lease;
      }
    else 
      {
        // Reject the bind request
        throw InvalidDuration();
      }
  }

  void cancel_lease (Lease_ptr lease) 
  {
    CosNaming::Name_var name = lease->get_name ();
    
    // Delegate to the Naming Service
    name_service_->unbind (name);
    
    // Cancel timer with the reactor
    reactor_->unregister_timer (this, lease);
  }
  
  TimeBase::TimeT prolong_lease (Lease_ptr lease, 
                                 TimeBase::TimeT duration) 
    throw (InvalidDuration)
  {
    if (this->duration_is_acceptable (duration)) 
      {
        // Reschedule the timer with the reactor for the 
        // new duration of the lease
        reactor_->unregister_timer (this, lease);
        reactor_->register_timer (duration, 
                                  this,
                                  lease);
      }
    else // Reject the bind request
      {
        throw InvalidDuration();
      }
  }
  
  
  void on_timer_expire (Lease_ptr lease)
  {
    LeaseHolder_var lease_holder = 
      lease->get_lease_holder ();
    
    // Notify lease holder of lease expriation
    lease_holder->lease_expired (lease);
    
    if (lease->get_remaining_time () <= 0)
      {
        // If the lease did not get renewed by the lease holder
        lease->expired ();
        CosNaming::Name_var name = lease->get_name ();
        name_service_->unbind (name);
      }
  }
  
private:
  bool duration_is_acceptable (TimeBase::TimeT time)
  {
    return TRUE;
  }
  
  TimeBase::TimeT current_time ()
  {
  }
  
  CosNaming::NamingContext_ptr name_service_;
  Reactor *reactor_;
};

These pages document the source code of the patterns Lookup, Eager Acquisition, and Leasing.

Copyright 2004 John Wiley and Sons. All Rights Reserved.