Hierarchy

  • EventEmitter
    • ClientSubscription

Implements

Constructors

Properties

hasSession: boolean

return true if the subscription is attached to a valid session

isActive: boolean

true is the subscription is fully active

lifetimeCount: number
maxKeepAliveCount: number
maxNotificationsPerPublish: number
priority: number
publishingEnabled: boolean
publishingInterval: number
session: ClientSession

return the session associated with the subscription. (may throw if the session is not valid)

subscriptionId: number
timeoutHint: number
ignoreNextWarning: boolean

Methods

  • Type Parameters

    • K

    Parameters

    • error: Error
    • event: string | symbol
    • Rest...args: AnyRest

    Returns void

  • Alias for emitter.on(eventName, listener).

    Type Parameters

    • K

    Parameters

    • eventName: string | symbol
    • listener: ((...args: any[]) => void)
        • (...args): void
        • Parameters

          • Rest...args: any[]

          Returns void

    Returns this

    v0.1.26

  • Synchronously calls each of the listeners registered for the event named eventName, in the order they were registered, passing the supplied arguments to each.

    Returns true if the event had listeners, false otherwise.

    import { EventEmitter } from 'node:events';
    const myEmitter = new EventEmitter();

    // First listener
    myEmitter.on('event', function firstListener() {
    console.log('Helloooo! first listener');
    });
    // Second listener
    myEmitter.on('event', function secondListener(arg1, arg2) {
    console.log(`event with parameters ${arg1}, ${arg2} in second listener`);
    });
    // Third listener
    myEmitter.on('event', function thirdListener(...args) {
    const parameters = args.join(', ');
    console.log(`event with parameters ${parameters} in third listener`);
    });

    console.log(myEmitter.listeners('event'));

    myEmitter.emit('event', 1, 2, 3, 4, 5);

    // Prints:
    // [
    // [Function: firstListener],
    // [Function: secondListener],
    // [Function: thirdListener]
    // ]
    // Helloooo! first listener
    // event with parameters 1, 2 in second listener
    // event with parameters 1, 2, 3, 4, 5 in third listener

    Type Parameters

    • K

    Parameters

    • eventName: string | symbol
    • Rest...args: AnyRest

    Returns boolean

    v0.1.26

  • Returns an array listing the events for which the emitter has registered listeners. The values in the array are strings or Symbols.

    import { EventEmitter } from 'node:events';

    const myEE = new EventEmitter();
    myEE.on('foo', () => {});
    myEE.on('bar', () => {});

    const sym = Symbol('symbol');
    myEE.on(sym, () => {});

    console.log(myEE.eventNames());
    // Prints: [ 'foo', 'bar', Symbol(symbol) ]

    Returns (string | symbol)[]

    v6.0.0

  • Returns the current max listener value for the EventEmitter which is either set by emitter.setMaxListeners(n) or defaults to defaultMaxListeners.

    Returns number

    v1.0.0

  • Returns Promise<MonitoredItemData>

  • Parameters

    Returns void

  • Returns the number of listeners listening for the event named eventName. If listener is provided, it will return how many times the listener is found in the list of the listeners of the event.

    Type Parameters

    • K

    Parameters

    • eventName: string | symbol

      The name of the event being listened for

    • Optionallistener: Function

      The event handler function

    Returns number

    v3.2.0

  • Returns a copy of the array of listeners for the event named eventName.

    server.on('connection', (stream) => {
    console.log('someone connected!');
    });
    console.log(util.inspect(server.listeners('connection')));
    // Prints: [ [Function] ]

    Type Parameters

    • K

    Parameters

    • eventName: string | symbol

    Returns Function[]

    v0.1.26

  • add a monitor item to the subscription

    @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 );

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

    @example:

    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 );

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

    @example:

    var filter = new 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
    

    );

    Parameters

    Returns Promise<ClientMonitoredItem>

  • Parameters

    Returns void

  • Alias for emitter.removeListener().

    Type Parameters

    • K

    Parameters

    • eventName: string | symbol
    • listener: ((...args: any[]) => void)
        • (...args): void
        • Parameters

          • Rest...args: any[]

          Returns void

    Returns this

    v10.0.0

  • Parameters

    • event: string | symbol
    • listener: ((...args: any[]) => void)
        • (...args): void
        • Parameters

          • Rest...args: any[]

          Returns void

    Returns this

  • Adds the listener function to the beginning of the listeners array for the event named eventName. No checks are made to see if the listener has already been added. Multiple calls passing the same combination of eventName and listener will result in the listener being added, and called, multiple times.

    server.prependListener('connection', (stream) => {
    console.log('someone connected!');
    });

    Returns a reference to the EventEmitter, so that calls can be chained.

    Type Parameters

    • K

    Parameters

    • eventName: string | symbol

      The name of the event.

    • listener: ((...args: any[]) => void)

      The callback function

        • (...args): void
        • Parameters

          • Rest...args: any[]

          Returns void

    Returns this

    v6.0.0

  • Adds a one-timelistener function for the event named eventName to the beginning of the listeners array. The next time eventName is triggered, this listener is removed, and then invoked.

    server.prependOnceListener('connection', (stream) => {
    console.log('Ah, we have our first user!');
    });

    Returns a reference to the EventEmitter, so that calls can be chained.

    Type Parameters

    • K

    Parameters

    • eventName: string | symbol

      The name of the event.

    • listener: ((...args: any[]) => void)

      The callback function

        • (...args): void
        • Parameters

          • Rest...args: any[]

          Returns void

    Returns this

    v6.0.0

  • Returns a copy of the array of listeners for the event named eventName, including any wrappers (such as those created by .once()).

    import { EventEmitter } from 'node:events';
    const emitter = new EventEmitter();
    emitter.once('log', () => console.log('log once'));

    // Returns a new Array with a function `onceWrapper` which has a property
    // `listener` which contains the original listener bound above
    const listeners = emitter.rawListeners('log');
    const logFnWrapper = listeners[0];

    // Logs "log once" to the console and does not unbind the `once` event
    logFnWrapper.listener();

    // Logs "log once" to the console and removes the listener
    logFnWrapper();

    emitter.on('log', () => console.log('log persistently'));
    // Will return a new Array with a single function bound by `.on()` above
    const newListeners = emitter.rawListeners('log');

    // Logs "log persistently" twice
    newListeners[0]();
    emitter.emit('log');

    Type Parameters

    • K

    Parameters

    • eventName: string | symbol

    Returns Function[]

    v9.4.0

  • Removes all listeners, or those of the specified eventName.

    It is bad practice to remove listeners added elsewhere in the code, particularly when the EventEmitter instance was created by some other component or module (e.g. sockets or file streams).

    Returns a reference to the EventEmitter, so that calls can be chained.

    Parameters

    • OptionaleventName: string | symbol

    Returns this

    v0.1.26

  • Removes the specified listener from the listener array for the event named eventName.

    const callback = (stream) => {
    console.log('someone connected!');
    };
    server.on('connection', callback);
    // ...
    server.removeListener('connection', callback);

    removeListener() will remove, at most, one instance of a listener from the listener array. If any single listener has been added multiple times to the listener array for the specified eventName, then removeListener() must be called multiple times to remove each instance.

    Once an event is emitted, all listeners attached to it at the time of emitting are called in order. This implies that any removeListener() or removeAllListeners() calls after emitting and before the last listener finishes execution will not remove them fromemit() in progress. Subsequent events behave as expected.

    import { EventEmitter } from 'node:events';
    class MyEmitter extends EventEmitter {}
    const myEmitter = new MyEmitter();

    const callbackA = () => {
    console.log('A');
    myEmitter.removeListener('event', callbackB);
    };

    const callbackB = () => {
    console.log('B');
    };

    myEmitter.on('event', callbackA);

    myEmitter.on('event', callbackB);

    // callbackA removes listener callbackB but it will still be called.
    // Internal listener array at time of emit [callbackA, callbackB]
    myEmitter.emit('event');
    // Prints:
    // A
    // B

    // callbackB is now removed.
    // Internal listener array [callbackA]
    myEmitter.emit('event');
    // Prints:
    // A

    Because listeners are managed using an internal array, calling this will change the position indices of any listener registered after the listener being removed. This will not impact the order in which listeners are called, but it means that any copies of the listener array as returned by the emitter.listeners() method will need to be recreated.

    When a single function has been added as a handler multiple times for a single event (as in the example below), removeListener() will remove the most recently added instance. In the example the once('ping') listener is removed:

    import { EventEmitter } from 'node:events';
    const ee = new EventEmitter();

    function pong() {
    console.log('pong');
    }

    ee.on('ping', pong);
    ee.once('ping', pong);
    ee.removeListener('ping', pong);

    ee.emit('ping');
    ee.emit('ping');

    Returns a reference to the EventEmitter, so that calls can be chained.

    Type Parameters

    • K

    Parameters

    • eventName: string | symbol
    • listener: ((...args: any[]) => void)
        • (...args): void
        • Parameters

          • Rest...args: any[]

          Returns void

    Returns this

    v0.1.26

  • By default EventEmitters will print a warning if more than 10 listeners are added for a particular event. This is a useful default that helps finding memory leaks. The emitter.setMaxListeners() method allows the limit to be modified for this specific EventEmitter instance. The value can be set to Infinity (or 0) to indicate an unlimited number of listeners.

    Returns a reference to the EventEmitter, so that calls can be chained.

    Parameters

    • n: number

    Returns this

    v0.3.5

  • Returns Promise<void>

  • Parameters

    Returns void

Events

  • Parameters

    • event: string | symbol
    • listener: ((...args: any[]) => void)
        • (...args): void
        • Parameters

          • Rest...args: any[]

          Returns void

    Returns this

  • notify the observers that the subscription has now started started

    Parameters

    • event: "started"
    • eventHandler: ((subscriptionId: number) => void)
        • (subscriptionId): void
        • Parameters

          • subscriptionId: number

          Returns void

    Returns this

  • notify the observers tha the client subscription has terminated terminated

    Parameters

    • event: "terminated"
    • eventHandler: (() => void)
        • (): void
        • Returns void

    Returns this

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

    Parameters

    Returns this

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

    Parameters

    • event: "keepalive"
    • eventHandler: (() => void)
        • (): void
        • Returns void

    Returns this

  • notify the observers that an error has occurred internal_error

    Parameters

    • event: "internal_error"
    • eventHandler: ((err: Error) => void)
        • (err): void
        • Parameters

          • err: Error

          Returns void

    Returns this

  • Parameters

    Returns this

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

    Parameters

    Returns this

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

    Parameters

    Returns this

  • Parameters

    • event: "error"
    • eventHandler: ((err: Error) => void)
        • (err): void
        • Parameters

          • err: Error

          Returns void

    Returns this