API Docs for: 0.0.57
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Subscription Class

The Subscription class used in the OPCUA server side.

Constructor

Subscription

(
  • options
)

Parameters:

  • options Object
    • id Integer
      • a unique identifier
    • publishingInterval Integer
    • maxKeepAliveCount Integer
    • lifeTimeCount Integer
    • publishingEnabled Boolean
    • maxNotificationsPerPublish Integer
    • priority Byte

Methods

_addNotificationMessage

(
  • notificationData
)

Parameters:

  • notificationData ArrayEventNotificationList | StatusChangeNotification>

_createMonitoredItemStep2

(
  • timestampsToReturn
  • monitoredItemCreateRequest
  • node
)
subscription_service.MonitoredItemCreateResult private

Parameters:

Returns:

subscription_service.MonitoredItemCreateResult:

_popNotificationToSend

() NotificationMessage

Extract the next Notification that is ready to be sent to the client.

Returns:

NotificationMessage:

the Notification to send._pending_notifications

_publish_pending_notifications *

() private

_publish_pending_notifications send a "notification" event:

_sendKeepAliveResponse

() private

_tick

() private

acknowledgeNotification

(
  • sequenceNumber
)
StatusCode

Parameters:

  • sequenceNumber Number

Returns:

adjustSamplingInterval

(
  • samplingInterval
  • node
)
Number | private

adjust monitored item sampling interval

  • an samplingInterval ===0 means that we use a event-base model ( no sampling)
  • otherwise the sampling is adjusted

Parameters:

  • samplingInterval Object
  • node Object

Returns:

Number | :

discardOldSentNotifications

() private

discardOldSentNotification find all sent notification message that have expired keep-alive and destroy them.

getAvailableSequenceNumbers

() Integer

returns in an array the sequence numbers of the notifications that haven't been acknowledged yet.

Returns:

Integer:

getMonitoredItem

(
  • monitoredItemId
)
MonitoredItem

get a monitoredItem by Id.

Parameters:

  • monitoredItemId Number

    the id of the monitored item to get.

Returns:

getMonitoredItems

(
  • result.serverHandles
)

getMonitoredItems is used to get information about monitored items of a subscription.Its intended use is defined in Part 4. This method is the implementation of the Standard OPCUA GetMonitoredItems Method.

Parameters:

  • result.serverHandles Int32

    Array of serverHandles for all MonitoredItems of the subscription identified by subscriptionId. result.clientHandles {Int32[]} Array of clientHandles for all MonitoredItems of the subscription identified by subscriptionId. result.statusCode {StatusCode} from spec: This method can be used to get the list of monitored items in a subscription if CreateMonitoredItems failed due to a network interruption and the client does not know if the creation succeeded in the server.

increaseKeepAliveCounter

() private

increaseLifeTimeCounter

() private

modify

(
  • param
)

Parameters:

  • param Object
    • requestedPublishingInterval Duration

      requestedPublishingInterval =0 means fastest possible

    • requestedLifetimeCount Counter

      requestedLifetimeCount ===0 means no change

    • requestedMaxKeepAliveCount Counter

      requestedMaxKeepAliveCount ===0 means no change

    • maxNotificationsPerPublish Counter
    • priority Byte

notificationHasExpired

(
  • notification
)
Boolean

returns true if the notification has expired

Parameters:

  • notification Object

Returns:

Boolean:

removeMonitoredItem

(
  • monitoredItemId
)

remove a monitored Item from the subscription.

Parameters:

  • monitoredItemId Number

    the id of the monitored item to get.

resetKeepAliveCounter

() private

resetLifeTimeAndKeepAliveCounters

()

the server invokes the resetLifeTimeAndKeepAliveCounters method of the subscription when the server has send a Publish Response, so that the subscription can reset its life time counter.

resetLifeTimeCounter

() private

Reset the Lifetime Counter Variable to the value specified for the lifetime of a Subscription in the CreateSubscription Service( 5.13.2).

terminate Calling this method will also remove any monitored items.

()

Terminates the subscription.

Properties

disabledMonitoredItemCount

Number

number of disabled monitored items.

hasMonitoredItemNotifications true if monitored Item have uncollected Notifications

Boolean

hasPendingNotifications

Boolean

return True is there are pending notifications for this subscription. (i.e moreNotifications)

keepAliveCounterHasExpired

Boolean true if the keep alive counter has reach its limit. private

lifeTimeCount

Number

The life time count defines how many times the publish interval expires without having a connection to the client to deliver data. If the life time count reaches maxKeepAliveCount, the subscription will automatically terminate. OPCUA Spec: The life-time count shall be a minimum of three times the keep keep-alive count.

Note: this has to be interpreted as without having a PublishRequest available

Default: 1

lifeTimeHasExpired

boolean - true if the subscription life time has expired.

True if the subscription life time has expired.

maxKeepAliveCount

Number

The keep alive count defines how many times the publish interval need to expires without having notifications available before the server send an empty message. OPCUA Spec says: a value of 0 is invalid.

Default: 10

maxNotificationsPerPublish

Number #default 0

The maximum number of notifications that the Client wishes to receive in a single Publish response. A value of zero indicates that there is no limit. The number of notifications per Publish is the sum of monitoredItems in the DataChangeNotification and events in the EventNotificationList.

monitoredItemCount

Number

number of monitored items.

monitoredItemIdCounter

Number

number of monitored Item

pendingNotificationsCount - number of pending notifications

Number

publishingInterval

Number

the Subscription publishing interval

Default: 1000

sentNotificationsCount

Number

number of sent notifications

timeToExpiration

Number

number of milliseconds before this subscription times out (lifeTimeHasExpired === true);

unacknowledgedMessageCount

Number

The number of unacknowledged messages saved in the republish queue.

Events

"terminated"

notify the subscription owner that the subscription has been terminated.

expired

notify the subscription owner that the subscription has expired by exceeding its life time.

keepalive

notify the subscription owner that a keepalive message has to be sent.

removeMonitoredItem

notify that a monitored item has been removed from the subscription

Event Payload: