The new implementation of the COS Event Service uses a factory to build all the objects and strategies it requires. The factory can be dynamically loaded using ACE Service Configurator, this is extremely convenient because the factory can also parse options in the Service Configurator script file.
The current implementation provides a default implementation for this Factory, this document describes the options used by this default implementation. Users can define their own implementation, with new ad-hoc strategies or with pre-selected strategies.
The COS channel uses the same service configurator
      file that the ORB uses, the default name for this file is
      svc.conf, but the ORB option
      -ORBSvcConf can be used to override this.
      The format of the file is described in detail in
      the service configurator documentation, but the relevant section
      for the event channel looks like this:
    
# Comments go here... # More comments if you want to... static CEC_Factory "-CECDispatching reactive ....."
All the event service factory options start with
      -CEC
| Option | Description | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| -CECDispatchingdispatching_strategy | Select the dispatching strategy used by the COS event service. A reactive strategy will use the same thread that received the event from the supplier to push the event to all the consumers. The mt strategy will also use a pool of threads, but the thread to dispatch is randomly selected. | ||||||||||||||||||
| -CECDispatchingThreadsnumber_of_threads | Select the number of threads used by the mt dispatching strategy. | ||||||||||||||||||
| -CECProxyConsumerLocklock_type | Select the lock type (null, thread or recursive) to synchronize access to the ProxyPushConsumer state. | ||||||||||||||||||
| -CECProxySupplierLocklock_type | Select the lock type (null, thread or recursive) to synchronize access to the ProxyPushSupplier state. | ||||||||||||||||||
| -CECUseORBIdorbid | Set the name of the ORB used by the event service, only useful in applications that create multiple ORBs and activate the event service in one of them. | ||||||||||||||||||
| -CECConsumerControlpolicy | Select the consumer control policy (null or reactive) to detect and discard broken consumers. | ||||||||||||||||||
| -CECSupplierControlpolicy | Select the supplier control policy (null or reactive) to detect and discard broken suppliers. | ||||||||||||||||||
| -CECConsumerControlPeriodperiod | Set the period (in microseconds) used by the reactive consumer control policy to poll the state of the consumers. | ||||||||||||||||||
| -CECSupplierControlPeriodperiod | Set the period (in microseconds) used by the reactive supplier control policy to poll the state of the suppliers. | ||||||||||||||||||
| -CECConsumerControlTimeouttimeout | Set the relative roundtrip timeout for push and pull consumers. The default is 10000 microseconds. This relative roundtrip timeout is utilized when each consumer attached to the supplier is queried. If querying any one of the consumers times out, it may be disconnected depending on the -CECProxyDisconnectRetries setting. This option can also be referenced as -CECConsumerControlRoundtripTimeout. | ||||||||||||||||||
| -CECSupplierControlTimeouttimeout | Set the relative roundtrip timeout for push or pull suppliers. The default is 10000 microseconds. This relative roundtrip timeout is utilized when each supplier attached to the consumer is queried. If querying any one of the suppliers times out, it may be disconnected depending on the -CECProxyDisconnectRetries setting. This option can also be referenced as -CECSupplierControlRoundtripTimeout. | ||||||||||||||||||
| -CECReactivePullingPeriodperiod | Set the period (in microseconds) used by the reactive pulling strategy to poll all the PullSuppliers for an event. | ||||||||||||||||||
| -CECProxyConsumerCollectionflag[:flags] | Configure the data structure and strategies used to
              implement collections of
               
 | ||||||||||||||||||
| -CECProxySupplierCollectionflag[:flags] | Configure the data structure and strategies used to
              implement collections of  | ||||||||||||||||||
| -CECProxyDisconnectRetriesnumber of retries | This determines the number of times a consumer or supplier can be "unresponsive" before the supplier or consumer control will disconnect it. The default is zero retries. | 
The TAO_CEC_EventChannel class implements the
      CosEventChannelAdmin::EventChannel interface;
      this class takes one mandatory and two optional parameters in
      its constructor:
    
  TAO_CEC_EventChannel (const TAO_CEC_EventChannel_Attributes& attributes,
                        TAO_CEC_Factory* factory = 0,
                        int own_factory = 0);
    The factory is an optional parameter to override
      the default strategy factory used by the event channel,
      the event channel will destroy the factory if the
      own_factory argument is true.
    
The attributes parameter can be used to fine tune
      some of the algorithms and strategies used by the event channel,
      the default values are probably OK for most applications.
      Notice that the attributes include the POA used to activate the
      ConsumerAdmin, SupplierAdmin, ProxyPushConsumer,
      ProxyPushSupplier, ProxyPullConsumer and the ProxyPullSupplier
      objects;
      these POAs must have the IMPLICIT_ACTIVATION and the
      SYSTEM_ID policies (as the RootPOA does).
    
| Attribute | Description | 
|---|---|
| consumer_reconnect | If the attribute is not zero then the same consumer can
            call connect_push_consumeron its
            ProxyPushSupplier multiple times to change its
            subscriptions;
            this is usually more efficient that disconnecting and
            connecting again. | 
| supplier_reconnect | If the attribute is not zero then the same supplier can
            call connect_push_supplieron its
            ProxyPushConsumer multiple times to change its
            publications;
            this is usually more efficient that disconnecting and
            connecting again. | 
| disconnect_callbacks | It not zero the event channel will send disconnect
            callbacks when a disconnect method is called on a Proxy.
            In other words, if a consumer calls disconnect_push_supplier()on its proxy the
            EC will invokedisconnect_push_consumer()on the consumer.  A similar thing is done for suppliers.
            It is a matter of debate what the spec requires for the
            regular event service. | 
| busy_hwm | When the delayed flag is set on proxy collections, this flag controls the maximum number of threads that can simultaneously iterate over the collection before blocking. It can be used to avoid starvation in delayed updates on the collection. | 
| max_write_delay | When the delayed flag is set on proxy collections, this flag controls the maximum number of threads that will initiate dispatching after a change has been posted. Any thread after that is blocked until the operations are performed. It can be used to completely stop starvation of delayed updates on the collection. | 
| supplier_poa | The POA used by the event channel to activate SupplierAdmin and SupplierProxy objects. | 
| consumer_poa | The POA used by the event channel to activate ConsumerAdmin and ConsumerProxy objects. | 
Back to the TAO components documentation.
Carlos O'Ryan Last modified: Fri Apr 20 15:24:09 CDT 2001