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/* -*- C++ -*- */
// $Id$
//
// ============================================================================
//
// = LIBRARY
// ORBSVCS Real-time Event Channel
//
// = FILENAME
// EC_SupplierFiltering
//
// = AUTHOR
// Carlos O'Ryan (coryan@cs.wustl.edu)
//
// = DESCRIPTION
// Define the TAO_EC_SupplierFiltering interface and some simple
// implementations.
//
// = CREDITS
// Based on previous work by Tim Harrison (harrison@cs.wustl.edu)
// and other members of the DOC group.
// More details can be found in:
// http://www.cs.wustl.edu/~schmidt/oopsla.ps.gz
// http://www.cs.wustl.edu/~schmidt/JSAC-98.ps.gz
//
//
// ============================================================================
#ifndef TAO_EC_SUPPLIERFILTERING_H
#define TAO_EC_SUPPLIERFILTERING_H
#include "orbsvcs/RtecEventCommC.h"
#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */
class TAO_EC_ProxyPushSupplier;
class TAO_EC_ProxyPushConsumer;
class TAO_EC_Event_Channel;
class TAO_ORBSVCS_Export TAO_EC_SupplierFiltering
{
// = TITLE
// The strategy to handle filtering close to the supplier.
//
// = DESCRIPTION
// After an event is received by the a ProxyPushConsumer it must
// be dispatched to the right set of ProxyPushSuppliers;
// determining this set is the task of this class.
// Notice that this is an implicit form of filtering, because the
// ProxyPushSuppliers outside the set will *not* receive the
// event.
//
// Several implementations are possible:
//
// - Each ProxyPushConsumer keeps a list of ProxyPushSuppliers,
// using the subscriptions and publications to find potential
// matches.
// - Each ProxyPushConsumer keeps several such lists, indexed by
// event type and/or source, this has the advantage of further
// minimizing the set of ProxyPushSuppliers invoked.
// - A single list of consumers is kept (global for the event
// channel), such a list results is faster updates and requires
// an smaller memory footprint.
// - Multiple global lists are kept, indexed by type and/or
// source, this is a tradeoff between the solutions above.
// - No list is kept, the events are sent to the consumers which
// must filter out what they want, this is good when no
// filtering is wanted or when the amount of filtering is coarse
// i.e. each event goes to a large subset of the
// ProxyPushSuppliers.
//
// Different applications will require to use different
// implementations of this class; as usual the EC_Factory will
// create the right instance.
//
public:
virtual ~TAO_EC_SupplierFiltering (void);
// Destructor
virtual void bind (TAO_EC_ProxyPushConsumer* consumer) = 0;
// Whenever a ProxyPushConsumer is initialized it calls this method
// to inform the FilteringStrategy of its identity.
// Strategies that do not keep ProxyPushConsumer specific
// information, or that are shared between multiple
// ProxyPushConsumers can ignore this message.
virtual void unbind (TAO_EC_ProxyPushConsumer* consumer) = 0;
// Wheneve a ProxyPushConsumer is about to be destroyed it calls
// this method to inform the FilteringStrategy that it should
// release any resources related to it.
// Filtering strategies that are bound to a particular ProxyConsumer
// can use this opportunity to destroy themselves; filtering
// strategies that do not keep ProxyPushConsumer specific
// information can simply ignore the message.
virtual void connected (TAO_EC_ProxyPushSupplier* supplier,
CORBA::Environment &env) = 0;
virtual void disconnected (TAO_EC_ProxyPushSupplier* supplier,
CORBA::Environment &env) = 0;
// Concrete implementations can use this methods to keep track of
// the consumers interested in this events.
virtual void push (const RtecEventComm::EventSet& event,
CORBA::Environment &) = 0;
// The ProxyPushConsumer delegates on this class to actually send
// the event.
};
// ****************************************************************
class TAO_EC_Null_SupplierFiltering : public TAO_EC_SupplierFiltering
{
// = TITLE
// A null filtering strategy.
//
// = DESCRIPTION
// This strategy does no filtering, it is useful for backends of
// the CosEventChannel, testing and broadcasters; it uses the
// ConsumerAdmin to find all the consumers and pushes the event to
// all of them.
//
public:
TAO_EC_Null_SupplierFiltering (TAO_EC_Event_Channel* ec);
// Constructor
// = The TAO_EC_SupplierFiltering methods.
virtual void bind (TAO_EC_ProxyPushConsumer* consumer);
virtual void unbind (TAO_EC_ProxyPushConsumer* consumer);
virtual void connected (TAO_EC_ProxyPushSupplier* supplier,
CORBA::Environment &env);
virtual void disconnected (TAO_EC_ProxyPushSupplier* supplier,
CORBA::Environment &env);
virtual void push (const RtecEventComm::EventSet& event,
CORBA::Environment &);
private:
TAO_EC_Event_Channel *event_channel_;
// The event channel, used to locate the set of consumers.
};
#if defined (__ACE_INLINE__)
#include "EC_SupplierFiltering.i"
#endif /* __ACE_INLINE__ */
#endif /* TAO_EC_SUPPLIERFILTERING_H */
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