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/* -*- C++ -*- */
// $Id$
//
// ============================================================================
//
// = LIBRARY
// TAO services
//
// = FILENAME
// EC_Gateway
//
// = AUTHOR
// Carlos O'Ryan
//
// = DESCRIPTION
// This class can be used to connect two event channels; the class
// connects to a "remote" EC as a consumer, it also connects to the
// <local> EC as a supplier of events, this later EC is usually
// collocated.
// The QoS parameters for both connections must be provided by the
// user.
// To avoid infinite loops of events the Gateway descreases the TTL
// field of the events and will not deliver any events with TTL less
// than or equal to 0.
//
// = TODO
// The class makes an extra copy of the events, we need to
// investigate if closer collaboration with its collocated EC could
// be used to remove that copy.
//
// ============================================================================
#ifndef TAO_EC_GATEWAY_H
#define TAO_EC_GATEWAY_H
#include "orbsvcs/RtecEventChannelAdminC.h"
#include "orbsvcs/RtecEventCommS.h"
#include "orbsvcs/Channel_Clients_T.h"
class TAO_Export TAO_EC_Gateway
//
// = TITLE
// Event Channel Gateway.
//
// = DESCRIPTION
// This class mediates among two event channels, it connects as a
// consumer of events with a remote event channel, and as a supplier
// of events with the local EC.
// As a consumer it gives a QoS designed to only accept the events
// in which *local* consumers are interested.
// Eventually the local EC should create this object and compute its
// QoS in an automated manner; but this requires some way to filter
// out the peers registered as consumers, otherwise we will get
// loops in the QoS graph.
// It uses exactly the same set of events in the publications list
// when connected as a supplier.
//
// = NOTES
// An alternative implementation would be to register with the
// remote EC as a supplier, and then filter on the remote EC, but
// one of the objectives is to minimize network traffic.
// On the other hand the events will be pushed to remote consumers,
// event though they will be dropped upon receipt (due to the TTL
// field); IMHO this is another suggestion that the EC needs to know
// (somehow) which consumers are truly its peers in disguise.
//
//
{
public:
TAO_EC_Gateway (void);
~TAO_EC_Gateway (void);
int open (RtecEventChannelAdmin::EventChannel_ptr remote_ec,
RtecEventChannelAdmin::EventChannel_ptr local_ec,
const RtecEventChannelAdmin::ConsumerQOS& subscriptions,
const RtecEventChannelAdmin::SupplierQOS& publications,
CORBA::Environment &_env);
// Establish the connections.
void disconnect_push_supplier (CORBA::Environment &);
// The channel is disconnecting.
void disconnect_push_consumer (CORBA::Environment &);
// The channel is disconnecting.
void push (const RtecEventComm::EventSet &events,
CORBA::Environment &);
// This is the Consumer side behavior, it pushes the events to the
// local event channel.
int shutdown (CORBA::Environment&);
private:
ACE_PushConsumer_Adapter<TAO_EC_Gateway> consumer_;
// Our consumer personality....
ACE_PushSupplier_Adapter<TAO_EC_Gateway> supplier_;
// Our supplier personality....
RtecEventChannelAdmin::ProxyPushConsumer_var consumer_proxy_;
// We talk to the EC (as a supplier) using this proxy.
RtecEventChannelAdmin::ProxyPushSupplier_var supplier_proxy_;
// We talk to the EC (as a consumer) using this proxy.
};
#endif /* ACE_EVENT_CHANNEL_H */
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