The NodeOPCUA API The NodeOPCUA API

  • API Docs for Version: 0.1.0-pre

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    ClientSubscription Class

    Extends EventEmitter
    Defined in: packages\node-opcua-client\src\client_subscription.js:30
    Module: opcua.client

    a object to manage a subscription on the client side.

    Constructor

    ClientSubscription

    (
    • session
    • options
    )

    Defined in packages\node-opcua-client\src\client_subscription.js:30

    Parameters:

    • session Object
    • options Object
      • requestedPublishingInterval Number
      • requestedLifetimeCount Number
      • requestedMaxKeepAliveCount Number
      • maxNotificationsPerPublish Number
      • publishingEnabled Boolean
      • priority Number

    Methods

    monitor

    (
    • itemToMonitor
    • requestedParameters
    • timestampsToReturn
    • [done]
    )
    ClientMonitoredItem async

    Defined in packages\node-opcua-client\src\client_subscription.js:436

    add a monitor item to the subscription

    Parameters:

    • itemToMonitor ReadValueId
      • nodeId NodeId
      • attributeId AttributeId
      • indexRange Null | NumericRange
      • dataEncoding
    • requestedParameters MonitoringParameters
      • clientHandle IntegerId
      • samplingInterval Duration
      • filter ExtensionObject | Null

        EventFilter/DataChangeFilter

      • queueSize Counter
      • discardOldest Boolean
    • timestampsToReturn TimestampsToReturn

      //{TimestampsToReturnId}

    • [done] Function optional

      optional done callback

    Returns:

    ClientMonitoredItem:

    Monitoring a simple Value Change

    Example:

    :

    clientSubscription.monitor( // itemToMonitor: { nodeId: "ns=0;i=2258", attributeId: AttributeIds.Value, indexRange: null, dataEncoding: { namespaceIndex: 0, name: null } }, // requestedParameters: { samplingInterval: 3000, filter: null, queueSize: 1, discardOldest: true }, TimestampsToReturn.Neither );

    Monitoring a Value Change With a DataChange Filter

    options.trigger {DataChangeTrigger} {Status|StatusValue|StatusValueTimestamp} options.deadbandType {DeadbandType} {None|Absolute|Percent} options.deadbandValue {Double}

    :

    clientSubscription.monitor( // itemToMonitor: { nodeId: "ns=0;i=2258", attributeId: AttributeIds.Value, }, // requestedParameters: { samplingInterval: 3000, filter: new DataChangeFilter({ trigger: DataChangeTrigger.StatusValue, deadbandType: DeadBandType.Absolute, deadbandValue: 0.1 }), queueSize: 1, discardOldest: true }, TimestampsToReturn.Neither );

    Monitoring an Event

    If the monitor attributeId is EventNotifier then the filter must be specified

    :

    var filter = new subscription_service.EventFilter({ selectClauses: [ { browsePath: [ {name: 'ActiveState' }, {name: 'id'} ]}, { browsePath: [ {name: 'ConditionName'} ]} ], whereClause: [] });

    clientSubscription.monitor( // itemToMonitor: { nodeId: "ns=0;i=2258", attributeId: AttributeIds.EventNotifier, indexRange: null, dataEncoding: { namespaceIndex: 0, name: null } }, // requestedParameters: { samplingInterval: 3000,

       filter: filter,
                    
                       queueSize: 1,
                       discardOldest: true
                    },
                    TimestampsToReturn.Neither

    );

    ping_server when a session is opened on a server, the client shall send request on a regular basis otherwise the server session object might time out. start_ping make sure that ping_server is called on a regular basis to prevent session to timeout.

    (
    • callback
    )

    Defined in packages\node-opcua-client\src\client_session_keepalive_manager.js:20

    Parameters:

    • callback Object

    recreateSubscriptionAndMonitoredItem

    ()

    Defined in packages\node-opcua-client\src\client_subscription.js:697

    utility function to recreate new subscription

    Properties

    hasTimedOut

    Boolean

    Defined in packages\node-opcua-client\src\client_subscription.js:92

    set to True when the server has notified us that this sbuscription has timed out ( maxLifeCounter x published interval without being able to process a PublishRequest

    Events

    failure raised when the server is not responding or is responding with en error to the keep alive read Variable value transaction

    Defined in packages\node-opcua-client\src\client_session_keepalive_manager.js:53

    internal_error

    Defined in packages\node-opcua-client\src\client_subscription.js:367

    notify the observers that an error has occurred

    Event Payload:

    • err Error

      the error

    item_added

    Defined in packages\node-opcua-client\src\client_subscription.js:398

    notify the observers that a new monitored item has been added to the subscription.

    Event Payload:

    keepalive

    Defined in packages\node-opcua-client\src\client_subscription.js:272

    notify the observers that a keep alive Publish Response has been received from the server.

    received_notifications

    Defined in packages\node-opcua-client\src\client_subscription.js:280

    notify the observers that some notifications has been received from the server in a PublishResponse each modified monitored Item

    started

    Defined in packages\node-opcua-client\src\client_subscription.js:108

    notify the observers that the subscription has now started

    status_changed

    Defined in packages\node-opcua-client\src\client_subscription.js:236

    notify the observers that the server has send a status changed notification (such as BadTimeout )

    terminated

    Defined in packages\node-opcua-client\src\client_subscription.js:326

    notify the observers tha the client subscription has terminated