urn:schemas-cosylab-com:EventChannel:1.0
element EventChannel

Properties

This component is not nillable.

Model

<EventChannel
  ConnectionReliability = xs:string : BestEffort
  DiscardPolicy = xs:string : AnyOrder
  EventReliability = xs:string : BestEffort
  IntegrationLogs = xs:boolean : false
  MaxConsumers = xs:long : 0
  MaxEventsPerConsumer = xs:long : 0
  MaxQueueLength = xs:long : 0
  MaxSuppliers = xs:long : 0
  OrderPolicy = xs:string : AnyOrder
  Priority = xs:long : 0
  RejectNewEvents = xs:boolean : true
  StartTimeSupported = xs:boolean : false
  StopTimeSupported = xs:boolean : false
  Timeout = xs:long : 0>
Events ?
</EventChannel>

ConnectionReliability

Connection reliability takes on the same enumerated values as EventReliability. This property defines whether the connection to the Notification Service between consumers and suppliers is persistent.

Type:

based on
with :

Default:

BestEffort

Use:

optional

Form:

unqualified

DiscardPolicy

This QoS property enables a user of the Notification Service to specify in what order the channel or a proxy supplier should begin discarding events in the case of an internal buffer overflow. This property applies on a per-channel basis only if it is set on a channel that has the RejectNewEvents admin property set to FALSE. If set on such a channel, the chosen discard policy will be applied whenever a supplier attempts to send a new event to the channel, and the total number of events already queued within the channel is equal to the MaxQueueLength administrative property. If set on a per- ConsumerAdmin basis, the chosen discard policy will be applied whenever the number of events queued on behalf of one of the consumers connected to one of the proxy suppliers created by the ConsumerAdmin exceeds the MaxEventsPerConsumer setting for that consumer. If set on a per-proxy supplier basis, the chosen discard policy will be applied whenever the number of events queued on behalf of the consumer connected to the proxy supplier exceeds the MaxEventsPerConsumer setting for that proxy supplier. Note that in these latter two cases, an event will only be discarded with respect to its scheduled delivery to the consumer(s) on whose behalf the policy is being applied. In other words, if the event targeted for discarding is scheduled for delivery to any consumer(s) on whose behalf the discard policy was not invoked, the event remains queued for those consumers. Constant values to represent the following settings are defined: * AnyOrder - Any event may be discarded on overflow. This is the default setting for this property. * FifoOrder - The first event received will be the first discarded. * LifoOrder - The last event received will be the first discarded. * PriorityOrder - Events should be discarded in priority order, such that lower priority events will be discarded before higher priority events. * DeadlineOrder - Events should be discarded in the order of shortest expiry deadline first. Note that this property has no meaning if set on a per-message basis.

Type:

based on
with :

Default:

AnyOrder

Use:

optional

Form:

unqualified

EventReliability

The value portion of this attribute has two well-defined settings: BestEffort (0) and Persistent (1). If set to 0, event can be treated as non-persistent and lost upon failure of the channel. At least one attempt must be made to transmit the event to each registered consumer, but in the case of a failure to send to any consumer, no further action need be taken. If set to 1, channel should make the event persistent, and attempt to retransmit upon channel recovery from failure. This setting only has meaning when ConnectionReliability is also set to 1, in which the combination essentially means guaranteed delivery.

Type:

based on
with :

Default:

BestEffort

Use:

optional

Form:

unqualified

IntegrationLogs

Giving this attribute a true value results in INFO logs for every sending and receiving of an event. This produces a huge number of log messages, and is only useful for debugging, but never in operations. @TODO: rename to something like "IsTraceEventsEnabled" because the historic coupling of tracing events with software integrations can be misleading.

Type:

xs:boolean

Default:

false

Use:

optional

Form:

unqualified

MaxConsumers

The maximum number of consumers that can be connected to the channel at any given time.

Type:

based on
with :

Default:

0

Use:

optional

Form:

unqualified

MaxEventsPerConsumer

An administrative property can be set on the channel to bound the maximum number of events a given channel is allowed to queue at any given point in time. Note, however, that a single badly behaved consumer could result in the channel holding the maximum number of events it is allowed to queue for an extended period of time, preventing further event communication through the channel. Thus, the MaximumEventsPerConsumer property helps to avoid this situation by bounding the maximum number of events the channel will queue on behalf of a given consumer. If set only on a per-channel basis, the value of this property applies to all consumers connected to the channel. If set on a per-ConsumerAdmin basis, this property applies to all consumers connected to proxy suppliers created by that ConsumerAdmin. If set on a per-proxy supplier basis, this property applies to the consumer connected to the given proxy supplier. Note that setting this property on a SupplierAdmin or proxy consumer has no meaning. Also note that the default setting of this property is 0, meaning that the proxy imposes no limits on the maximum number of events that may be queued for its consumer.

Type:

based on
with :

Default:

0

Use:

optional

Form:

unqualified

MaxQueueLength

The maximum number of events that will be queued by the channel before the channel begins discarding events (according to the Discard Policy QoS parameter) or rejecting new events (depending on the setting of the RejectNewEvents admin property) upon receipt of each new event.

Type:

based on
with :

Default:

0

Use:

optional

Form:

unqualified

MaxSuppliers

The maximum number of suppliers that can be connected to the channel at any given time.

Type:

based on
with :

Default:

0

Use:

optional

Form:

unqualified

OrderPolicy

This QoS property sets the policy used by a given proxy to order the events it has buffered for delivery (either to another proxy or a consumer). Constant values to represent the following settings are defined: * AnyOrder - Any ordering policy is permitted. * FifoOrder - Events should be delivered in the order of their arrival. * PriorityOrder - Events should be buffered in priority order, such that higher priority events will be delivered before lower priority events. * DeadlineOrder - Events should be buffered in the order of shortest expiry deadline first, such that events that are destined to timeout soonest should be delivered first. Note that this property has no meaning if set on a per-message basis.

Type:

based on
with :

Default:

AnyOrder

Use:

optional

Form:

unqualified

Priority

The event service does not define the order in which events are delivered to a consumer. One way to be explicit is to allow delivery to be based on the priority of an event. Priority is represented as a short value, where -32,767 is the lowest priority and 32,767 the highest. The default priority for all events is 0. By default, the notification channel will attempt to deliver messages to consumers in priority order.

Type:

based on
with :

Default:

0

Use:

optional

Form:

unqualified

RejectNewEvents

This value associated with this property is of type Boolean, where TRUE and FALSE have the following meanings: * TRUE: Attempts to push new events to the channel by push-style suppliers will result in the IMPL_LIMIT system exception being raised. * FALSE: When the total number of undelivered events within the channel is equal to MaxQueueLength, attempts to push new events to the channel by a push-style supplier will result in one of the currently queued undelivered events being discarded by the channel to make room for the new event. The discarded event will be chosen based on the setting of the DiscardPolicy QoS property.

Type:

xs:boolean

Default:

true

Use:

optional

Form:

unqualified

StartTimeSupported

QoS property is defined which has an associated boolean value, indicating whether or not the setting of StartTime on a per-message basis is supported.

Type:

xs:boolean

Default:

false

Use:

optional

Form:

unqualified

StopTimeSupported

QoS property is defined that has an associated boolean value, indicating whether or not the setting of StopTime on a per-message basis is supported.

Type:

xs:boolean

Default:

false

Use:

optional

Form:

unqualified

Timeout

Timeout, a TimeBase::TimeT encoded value, states a relative expiry time (e.g., 10 minutes from now), after which the event can be discarded. It is possible for a consumer to override the value associated with this property through the use of mapping filters. Note that the time value associated with the Timeout QoS property is viewed as relative to the time when the channel (i.e., the receiving proxy consumer) first received the event.

Type:

based on
with :

Default:

0

Use:

optional

Form:

unqualified

Source

<xs:element name="EventChannel" type="EventChannel"/>