TAO's Real-Time Event Channel can be configured at compilation time to use a different payload than its default. To do so there are several options:
To eliminate the CORBA::Any field in the
          event payload you should define the
          TAO_LACKS_EVENT_CHANNEL_ANY
          macro when invoking the IDL compiler.
          You can do as follows:
$ cd $TAO_ROOT/orbsvcs/orbsvcs $ make TAO_IDLFLAGS=-DTAO_LACKS_EVENT_CHANNEL_ANY
Similarly you can eliminate the octet sequence field in the event payload using:
$ cd $TAO_ROOT/orbsvcs/orbsvcs $ make TAO_IDLFLAGS=-DTAO_LACKS_EVENT_CHANNEL_OCTET_SEQUENCE
Finally you can provide your own event payload, to do
          this you should Replace the contents of the
          RtecDefaultEventData.idl
          and define some IDL structure named
          RtecEventData.
          For example, you could define you own event type as follows:
// Replace RtecDefaultEventData.idl with this:
struct RtecEventData
{
  sequence<long> my_event_payload;
};
      The new implementation of the real-time event channel 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.
There are currently several implementations of the factory.
TAO_EC_Default_Factory::init_svcs() with
          TAO_EC_TPC_Factory::init_svcs().
$TAO_ROOT/orbsvcs/orbsvcs/Event/EC_Null_Factory.h
      and $TAO_ROOT/orbsvcs/orbsvcs/Event/EC_Basic_Factory.h
      for details.
    
      In certain configurations such as mt and tpc,
      the RTES implementation uses something called
      TAO_EC_Queue, which is an in-memory queue that
      separates threads that receive push() invocations
      from suppliers from the threads that dispatch
      push() invocations to consumers.  A user of the
      RTES can configure some behaviors of this queue as well as
      behaviors when the queue reaches certain trigger points.  The
      configuration of these behaviors is a combination of
      compile-time and run-time specification.
    
The queue itself has two trigger points for the number of invocations in the queue:
TAO_EC_QUEUE_LWM and TAO_EC_QUEUE_HWM
    for the low-water mark and high-water mark, respectively.
    
      In addition, an application can specify what the RTES should do if a
      queue reaches the HWM, i.e., fills up.  This behavior is encapsulated in a
      derivation of an ACE_Service_Object, called
      TAO_EC_Queue_Full_Service_Object.  The RTES looks
      for a service object of a particular name (the default for this
      name is in macro TAO_EC_DEFAULT_QUEUE_FULL_SERVICE_OBJECT_NAME,
      which is "EC_QueueFullSimpleActions") and invokes
      queue_full_action() on the instance.  See class
      TAO_EC_Simple_Queue_Full_Action in file
      $TAO_ROOT/orbsvcs/orbsvcs/Event/EC_Dispatching_Task.h
      for an example.  This particular example can be configured to
      either wait or discard new invocations on
      reaching the HWM.
    
The real-time event 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 EC_Factory "-ECFiltering basic ....." # ...and optionally... static EC_QueueFullSimpleActions "[wait | discard]" # ...or you can define your own TAO_EC_Queue_Full_Service_Object, # give it whatever name you want and use -ECQueueFullServiceObject # (see below) to specify that object's service configurator tag.
The table below describes all of the options (and values) supported by these factories.
All the event service factory options start with
      -EC
| Option | Description | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| -ECDispatchingdispatching_strategy | Select the dispatching strategy used by the real-time
            event service. The reactive strategy uses the
            same thread that received the event from the supplier to
            push the event to all the consumers. The priority strategy (sched factory only) uses a prioritized pool of threads and queries the scheduling service to select the thread that dispatches each event. The mt strategy also uses a pool of threads, but the thread to dispatch is randomly selected. Does not apply to the tpc factory. | ||||||||||||||||||
| -ECDispatchingThreadsnumber_of_threads | Select the number of threads used by the mt
            dispatching strategy. Does not apply to the tpc factory. | ||||||||||||||||||
| -ECDispatchingThreadFlagsthread_flags:thread_priority | Provide flags and priority used for creation of
            dispatching threads. thread_flags is a set of THR_flags separated by the vertical bar
            ('|'), e.g.,THR_BOUND|THR_NEW_LWP|THR_SCOPE_SYSTEM.thread_priority is a numeric value indicating the desired priority at which the thread should be created. No range checking is performed on the value prior to passing to the thread creation function. Also note that priorities are platform-specific, so a valid value for a given set of flags on one platform may not work with the same flags on another platform. | ||||||||||||||||||
| -ECQueueFullServiceObjectservice_object_name | Used to specify the name/tag in the service configurator
            through which the RTEC should look for a "queue full
            service object". Will only have an effect on dispatch strategies that use TAO_EC_Queue. | ||||||||||||||||||
| -ECFilteringconsumer_filtering_strategy | Select the filtering strategy used by the consumers. The null filtering strategy will build trivial filters for all consumers. The basic filtering strategy supports disjunction, conjunction, logical and, negation, bitmask, and timeout filters based on the subscriptions passed by the consumer during the connect call. It only supports limited nesting of filter groups. The prefix filtering strategy supports all filter types that the basic strategy does and allows unlimited nesting of filter groups. When using the prefix strategy, the source field of the group filter must specify the number of children in the group. The priority filtering strategy (sched factory only) supports the same features as the basic filtering strategy, but it also collaborates with the scheduling service to build the dependency graph. | ||||||||||||||||||
| -ECSupplierFilteringsupplier_filtering_strategy | The event channel can also perform some filtering close to the suppliers by minimizing the number of consumers that are tested for given event. If the strategy is null then a global collection of consumers is maintained and each event is filtered by each consumer. If the strategy is per-supplier then the EC uses the supplier publications and the consumer subscriptions to determine which consumers could potentially be interested in events for each supplier. This set of consumers is usually smaller than the complete set and it is thus faster to traverse it, but keeping more collections of consumers increases the connection and disconnection time as well as the memory requirements. | ||||||||||||||||||
| -ECTimeouttimeout_strategy | A consumer can request that the event channel generate
            periodic or oneshot timeout events.
            This option controls the strategy to generate the
            timeouts,
            using reactive the same reactor used for the ORB
            is used by the event service.
            The priority strategy  (sched factory only) uses a
            prioritized group of
            threads, timeouts with higher rate are generated by
            threads of higher priority. NOTE: The priority strategy is not implemented | ||||||||||||||||||
| -ECObserverobserver | The event channel uses the Observer pattern to report
            changes in the subscriptions and publications of its
            suppliers and consumers; this is especially useful in the
            implementation of event channel gateways.
            The user can disable this feature by selecting the
            null strategy;
            whereas the basic strategy provides a simple, yet
            efficient implementation. reactive provides a 
            strategy in which an observer that is unreachable is removed
            from the observer list. NOTE: The default is to have the feature disabled. | ||||||||||||||||||
| -ECSchedulingscheduling_strategy | The event channel can collaborate with the scheduling
            service to build the dependency list between the consumers
            and the suppliers.
            If the null scheduling strategy is selected this
            feature is disabled,
            the priority strategy (sched factory only) enables this feature. NOTE: The default is to have the feature disabled. | ||||||||||||||||||
| -ECProxyConsumerLocklock_type | Select the lock type (null, thread or recursive) to synchronize access to the ProxyPushConsumer state. | ||||||||||||||||||
| -ECProxySupplierLocklock_type | Select the lock type (null, thread or recursive) to synchronize access to the ProxyPushSupplier state. | ||||||||||||||||||
| -ECUseORBIdorbid | 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. | ||||||||||||||||||
| -ECConsumerControlpolicy | Select the consumer control policy (null or reactive) to detect and discard broken consumers. | ||||||||||||||||||
| -ECSupplierControlpolicy | Select the supplier control policy (null or reactive) to detect and discard broken suppliers. | ||||||||||||||||||
| -ECConsumerControlPeriodperiod | Set the period (in microseconds) used by the reactive consumer control policy (set ECConsumerControl to reactive) to poll the state of the consumers. When set to 0 there is no polling but the reactive strategy is in place. | ||||||||||||||||||
| -ECSupplierControlPeriodperiod | Set the period (in microseconds) used by the reactive supplier control policy (set ECSupplierControl to reactive) to poll the state of the suppliers. When set to 0 there is no polling but the reactive strategy is in place. | ||||||||||||||||||
| -ECConsumerControlTimeouttimeout | Set the timeout period (in microseconds) used by the reactive consumer control policy (set ECConsumerControl to reactive) to detect a timeout when polling the state of the consumers. | ||||||||||||||||||
| -ECSupplierControlTimeouttimeout | Set the timeout period (in microseconds) used by the reactive supplier control policy (set ECSupplierControl to reactive) to detect a timeout when polling the state of the suppliers. | ||||||||||||||||||
| -ECProxyPushConsumerCollectionflag[:flags] | Configure the data structure and strategies used to
              implement collections of
               
 | ||||||||||||||||||
| -ECProxyPushSupplierCollectionflag[:flags] | Configure the data structure and strategies used to
              implement collections of  | ||||||||||||||||||
| -ECPushSupplierSet | Obsolete option, ignored. | ||||||||||||||||||
| -ECConsumerAdminLock | Obsolete option, ignored in the current version. | ||||||||||||||||||
| -ECSupplierAdminLock | Obsolete option, ignored in the current version. | ||||||||||||||||||
| -ECConsumerValidateConnectionvalidate_connection: 0 | 1 | When this option is set the connection from the Event Channel to the consumer will be created during the connect of the consumer, just before the consumer is added to the consumer list. By default the Event Channel will create the connection to the consumer at the moment the first event is pushed to the consumer. When the network is heavily loaded during this connect and a new event is pushed before the connection is establed, a new create connection request is done. When having very high connection establishment time (for example running on a WAN) and an interval that is much smaller than the connection establishment time it is wise to set this option. Else you get dozens of new connection request that can result in a stack overflow. Another option is to use BiDIR GIOP so that there is only one connection between Rtec and consumer but for this the Rtec and the consumer must be changed to set the BiDIR Policy, this is not implemented at this moment. | 
The TAO_EC_Event_Channel class implements the
      RtecEventChannelAdmin::EventChannel interface;
      this class takes one mandatory and two optional parameters in
      its constructor:
    
  TAO_EC_Event_Channel (const TAO_EC_Event_Channel_Attributes& attributes,
                        TAO_EC_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 and
      ProxyPushSupplier 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. | 
| 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. | 
| scheduler | Most configurations of the real-time event channel do not require an scheduler. If any of the strategies that require an scheduling service is selected then this attribute should be set appropiately. | 
| 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. | 
| disconnect_callbacks | If not zero, then the event channel sends disconnect callbacks when a disconnect method is called on a Proxy. For example, if a consumer calls disconnect_push_supplier() on its proxy the EC invokes disconnect_push_consumer() on the consumer. An analogous call is also made for suppliers when this attribute is set. By default, these callbacks are not made in this situation. | 
The TAO_EC_Gateway_IIOP_Factory is the factory for 
      the TAO_EC_Gateway_IIOP class. This factory can be 
      used to configure the settings of the IIOP Gateway using the 
      svc.conf file. The contents looks like this:
    
# Comments go here... # More comments if you want to... static EC_Gateway_IIOP_Factory "-ECGIIOPConsumerECControl null ....."
All the IIOP Gateway factory options start with
      -ECGIIOP
| Option | Description | 
|---|---|
| -ECGIIOPConsumerECControlpolicy | Select the consumer ec control policy (null or reactive or reconnect) to detect and handle broken consumer ec's. | 
| -ECGIIOPConsumerECControlPeriodperiod | Set the period (in microseconds) used by the reactive and reconnect consumer ec control policy (set ECGIIOPConsumerECControl to reactive or reconnect) to poll the state of the consumer ec. When set to 0 there is no polling but the reactive strategy is in place. | 
| -ECGIIOPConsumerECControlTimeouttimeout | Set the timeout period (in microseconds) used by the reactive and reconnect consumer ec control policy (set ECGIIOPConsumerECControl to reactive or reconnect) to detect a timeout when polling the state of the consumer ec. | 
| -ECGIIOPUseORBIdorbid | Set the name of the ORB used by the event gateway, only useful in applications that create multiple ORBs and activate the gateway in one of them. | 
| -ECGIIOPUseTTLuse_ttl: 0 | 1 | Set whether the IIOP Gateway uses the TTL or not. This is 1 by default. When set to 0 make sure that no recursive structure is build between ec's, else an event can keep looping for ever. Useful when there are no recursive structures and we want the gateway to transfer all events independent of their TTL because suppliers can be unaware about the maximum number of hops. In case this option is 0, the TTL in the event isn't decremented by the gateway also. | 
| -ECGIIOPUseConsumerProxyMapuse_consumer_proxy_map: 0 | 1 | Set whether the IIOP Gateway uses a map with a proxy push consumer for each unique source id or not. This is 1 by default meaning that a map is used. When set to 0 the gateway will just use one proxy push consumer to push events to the consumer ec. This options is useful when a lot of different source id's are used but there is no need for a different proxy push consumer for each source id. Setting this option to 0 then improves the performance. | 
| Option | Description | 
|---|---|
| -nservice_name | The name with which the Event Service registers itself in the Naming Service. | 
| -oior_file_name | The file to which the IOR of the Event Service will be written. | 
| -ppid_file_name | The process id of the Event Service will be written to this file | 
| -qec_object_id | The object ID for the Event Channel that will be used when a Persistent IOR is generated | 
| -b | Use BiDIR GIOP | 
| -x | Don't register the Event Service to the Naming Service | 
| -sglobal|local|none | Which scheduler should be used. The default is none. 
          Withlocalan in process scheduler is created. Withglobala scheduler is retrieved from the Naming Service | 
Back to the TAO components documentation. Last modified: Tue Oct 18 13:13:54 CDT 2005