@webda/otel • Readme | API

Class: OtelService<T>

Otel Service

Webda Modda

Extends

Service<T>

Type parameters

• T extends OtelServiceParameters

Constructors

new OtelService(webda, name, params)

new OtelService<T>(webda, name, params?): OtelService<T>

Parameters

• webda: Core<CoreEvents>

The main instance of Webda

• name: string

The name of the service

• params?: DeepPartial<T>

The parameters block define in the configuration file

Returns

OtelService<T>

Inherited from

Service<T>.constructor

Source

core/lib/services/service.d.ts:168

Properties

_createException

_createException: string

Inherited from

Service._createException

Source

core/lib/services/service.d.ts:149

_initException

_initException: any

Inherited from

Service._initException

Source

core/lib/services/service.d.ts:151

_initTime

_initTime: number

Inherited from

Service._initTime

Source

core/lib/services/service.d.ts:150

_name

protected _name: string

Service name

Inherited from

Service._name

Source

core/lib/services/service.d.ts:142

_webda

protected _webda: Core<CoreEvents>

Webda Core object

Inherited from

Service._webda

Source

core/lib/services/service.d.ts:138

logger

protected logger: Logger

Logger with class context

Inherited from

Service.logger

Source

core/lib/services/service.d.ts:155

loggerExporter

loggerExporter: LogRecordExporter

Source

otel/src/otel.ts:87

loggerProvider

loggerProvider: LoggerProvider

Source

otel/src/otel.ts:88

metrics?

protected metrics?: any

Get metrics

Inherited from

Service.metrics

Source

core/lib/services/service.d.ts:159

otelLogger

otelLogger: OtelLogger

Source

otel/src/otel.ts:86

parameters

protected parameters: T

Hold the parameters for your service

It will be bring from the webda.config.json

Inherited from

Service.parameters

Source

core/lib/services/service.d.ts:148

sdk

sdk: NodeSDK

Source

otel/src/otel.ts:78

stubs

stubs: Map<Object, Object>

Source

otel/src/otel.ts:80

wrapper

wrapper: InstrumentationNodeModuleDefinition<any>

Source

otel/src/otel.ts:79

captureRejectionSymbol

static readonly captureRejectionSymbol: typeof captureRejectionSymbol

Value: Symbol.for('nodejs.rejection')

See how to write a custom rejection handler.

Since

v13.4.0, v12.16.0

Inherited from

Service.captureRejectionSymbol

Source

otel/node_modules/@types/node/events.d.ts:402

captureRejections

static captureRejections: boolean

Value: boolean

Change the default captureRejections option on all new EventEmitter objects.

Since

v13.4.0, v12.16.0

Inherited from

Service.captureRejections

Source

otel/node_modules/@types/node/events.d.ts:409

defaultMaxListeners

static defaultMaxListeners: number

By default, a maximum of 10 listeners can be registered for any single event. This limit can be changed for individual EventEmitter instances using the emitter.setMaxListeners(n) method. To change the default for allEventEmitter instances, the events.defaultMaxListenersproperty can be used. If this value is not a positive number, a RangeErroris thrown.

Take caution when setting the events.defaultMaxListeners because the change affects allEventEmitter instances, including those created before the change is made. However, calling emitter.setMaxListeners(n) still has precedence over events.defaultMaxListeners.

This is not a hard limit. The EventEmitter instance will allow more listeners to be added but will output a trace warning to stderr indicating that a "possible EventEmitter memory leak" has been detected. For any singleEventEmitter, the emitter.getMaxListeners() and emitter.setMaxListeners()methods can be used to temporarily avoid this warning:

import { EventEmitter } from 'node:events';
const emitter = new EventEmitter();
emitter.setMaxListeners(emitter.getMaxListeners() + 1);
emitter.once('event', () => {
  // do stuff
  emitter.setMaxListeners(Math.max(emitter.getMaxListeners() - 1, 0));
});

The --trace-warnings command-line flag can be used to display the stack trace for such warnings.

The emitted warning can be inspected with process.on('warning') and will have the additional emitter, type, and count properties, referring to the event emitter instance, the event's name and the number of attached listeners, respectively. Its name property is set to 'MaxListenersExceededWarning'.

Since

v0.11.2

Inherited from

Service.defaultMaxListeners

Source

otel/node_modules/@types/node/events.d.ts:446

errorMonitor

static readonly errorMonitor: typeof errorMonitor

This symbol shall be used to install a listener for only monitoring 'error'events. Listeners installed using this symbol are called before the regular'error' listeners are called.

Installing a listener using this symbol does not change the behavior once an'error' event is emitted. Therefore, the process will still crash if no regular 'error' listener is installed.

Since

v13.6.0, v12.17.0

Inherited from

Service.errorMonitor

Source

otel/node_modules/@types/node/events.d.ts:395

Methods

`[captureRejectionSymbol]`()?

optional [captureRejectionSymbol](error, event, ...args): void

Parameters

• error: Error

• event: string

• ...args: any[]

Returns

void

Inherited from

Service.[captureRejectionSymbol]

Source

otel/node_modules/@types/node/events.d.ts:112

__clean()

__clean(): Promise<void>

Clean the service data, can only be used in test mode

Returns

Promise<void>

Inherited from

Service.__clean

Abstract

Source

core/lib/services/service.d.ts:319

_wrap()

protected _wrap(object, method, wrapper): void

Wrap a method

Parameters

• object: Object

• method: string

• wrapper: Function

Returns

void

Source

otel/src/otel.ts:206

addListener()

addListener(eventName, listener): this

Alias for emitter.on(eventName, listener).

Parameters

• eventName: string | symbol

• listener: (...args) => void

Returns

this

Inherited from

Service.addListener

Since

v0.1.26

Source

otel/node_modules/@types/node/events.d.ts:545

addRoute()

protected addRoute(url, methods, executer, openapi?, override?): void

Add a route dynamicaly

Parameters

• url: string

of the route can contains dynamic part like {uuid}

• methods: HttpMethodType[]

• executer: Function

Method to execute for this route

• openapi?: OpenAPIWebdaDefinition

• override?: boolean

Returns

void

Inherited from

Service.addRoute

Source

core/lib/services/service.d.ts:242

authorizeClientEvent()

authorizeClientEvent(_event, _context): boolean

Authorize a public event subscription

Parameters

• _event: string

• _context: OperationContext<any, any>

Returns

boolean

Inherited from

Service.authorizeClientEvent

Source

core/lib/services/service.d.ts:220

computeParameters()

computeParameters(): void

Used to compute or derivate input parameter to attribute

Returns

void

Inherited from

Service.computeParameters

Source

core/lib/services/service.d.ts:176

emit()

emit<Key>(event, data): boolean

Override to allow capturing long listeners

Type parameters

• Key extends string | number

Parameters

• event: symbol | Key

• data: Events[Key]

Returns

boolean

Inherited from

Service.emit

Source

core/lib/services/service.d.ts:289

emitSync()

emitSync<Key>(event, data): Promise<any[]>

Emit the event with data and wait for Promise to finish if listener returned a Promise

Type parameters

• Key extends string | number

Parameters

• event: Key

• data: Events[Key]

Returns

Promise<any[]>

Inherited from

Service.emitSync

Source

core/lib/services/service.d.ts:284

eventNames()

eventNames(): (string | symbol)[]

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)[]

Inherited from

Service.eventNames

Since

v6.0.0

Source

otel/node_modules/@types/node/events.d.ts:870

getClientEvents()

getClientEvents(): string[]

Return the events that an external system can subscribe to

Returns

string[]

Inherited from

Service.getClientEvents

Source

core/lib/services/service.d.ts:214

getDiagLevel()

getDiagLevel(): DiagLogLevel

Get diag level based on parameters

Returns

DiagLogLevel

Source

otel/src/otel.ts:98

getMaxListeners()

getMaxListeners(): number

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

Returns

number

Inherited from

Service.getMaxListeners

Since

v1.0.0

Source

otel/node_modules/@types/node/events.d.ts:722

getMetric()

getMetric<T>(type, configuration): T

Add service name label

Type parameters

• T = Counter<string> | Histogram<string> | Gauge<string>

Parameters

• type: Constructor<T, [MetricConfiguration<T>]>

• configuration: MetricConfiguration<T>

Returns

T

Inherited from

Service.getMetric

Source

core/lib/services/service.d.ts:208

getName()

getName(): string

Get service name

Returns

string

Inherited from

Service.getName

Source

core/lib/services/service.d.ts:313

getOpenApiReplacements()

getOpenApiReplacements(): any

Return variables for replacement in openapi

Returns

any

Inherited from

Service.getOpenApiReplacements

Source

core/lib/services/service.d.ts:247

getOperationId()

getOperationId(id): string

If undefined is returned it cancel the operation registration

Parameters

• id: string

Returns

string

Inherited from

Service.getOperationId

Source

core/lib/services/service.d.ts:234

getParameters()

getParameters(): T

Get the service parameters

Returns

T

Inherited from

Service.getParameters

Source

core/lib/services/service.d.ts:180

getService()

getService<K>(service): K

Return a webda service

Type parameters

• K extends Service<ServiceParameters, Events>

Parameters

• service: string

name to retrieve

Returns

K

Inherited from

Service.getService

Source

core/lib/services/service.d.ts:309

getUrl()

getUrl(url, _methods): string

Return the full path url based on parameters

Parameters

• url: string

relative url to service

• _methods: HttpMethodType[]

in case we need filtering (like Store)

Returns

string

absolute url or undefined if need to skip the Route

Inherited from

Service.getUrl

Source

core/lib/services/service.d.ts:228

getWebda()

getWebda(): Core<CoreEvents>

Return WebdaCore

Returns

Core<CoreEvents>

Inherited from

Service.getWebda

Source

core/lib/services/service.d.ts:184

init()

init(): Promise<OtelService<T>>

Will be called after all the Services are created

Returns

Promise<OtelService<T>>

Inherited from

Service.init

Abstract

Source

core/lib/services/service.d.ts:275

initMetrics()

initMetrics(): void

Init the metrics

Returns

void

Inherited from

Service.initMetrics

Source

core/lib/services/service.d.ts:201

initOperations()

initOperations(): void

Init the operations

Returns

void

Inherited from

Service.initOperations

Source

core/lib/services/service.d.ts:255

initRoutes()

initRoutes(): void

Init the routes

Returns

void

Inherited from

Service.initRoutes

Source

core/lib/services/service.d.ts:251

listenerCount()

listenerCount(eventName, listener?): number

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.

Parameters

• eventName: string | symbol

The name of the event being listened for

• listener?: Function

The event handler function

Returns

number

Inherited from

Service.listenerCount

Since

v3.2.0

Source

otel/node_modules/@types/node/events.d.ts:816

listeners()

listeners(eventName): Function[]

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] ]

Parameters

• eventName: string | symbol

Returns

Function[]

Inherited from

Service.listeners

Since

v0.1.26

Source

otel/node_modules/@types/node/events.d.ts:735

loadParameters()

loadParameters(params): ServiceParameters

Load the parameters for a service

Parameters

• params: DeepPartial<T>

Returns

ServiceParameters

Inherited from

Service.loadParameters

Source

core/lib/services/service.d.ts:172

log()

log(level, ...args): void

Parameters

• level: WorkerLogLevel

to log

• ...args: any[]

Returns

void

Inherited from

Service.log

Source

core/lib/services/service.d.ts:329

off()

off(eventName, listener): this

Alias for emitter.removeListener().

Parameters

• eventName: string | symbol

• listener: (...args) => void

Returns

this

Inherited from

Service.off

Since

v10.0.0

Source

otel/node_modules/@types/node/events.d.ts:695

on()

on<Key>(event, listener): this

Type the listener part

Type parameters

• Key extends string | number

Parameters

• event: symbol | Key

• listener: (evt) => void

Returns

this

Inherited from

Service.on

Source

core/lib/services/service.d.ts:297

onAsync()

onAsync<Key>(event, listener, queue?): void

Listen to an event as on(...) would do except that it will be asynchronous

Type parameters

• Key extends string | number

Parameters

• event: Key

• listener: (evt) => void

• queue?: string

Name of queue to use, can be undefined, queue name are used to define differents priorities

Returns

void

Inherited from

Service.onAsync

Source

core/lib/services/service.d.ts:304

once()

once(eventName, listener): this

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

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

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

By default, event listeners are invoked in the order they are added. Theemitter.prependOnceListener() method can be used as an alternative to add the event listener to the beginning of the listeners array.

import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.once('foo', () => console.log('a'));
myEE.prependOnceListener('foo', () => console.log('b'));
myEE.emit('foo');
// Prints:
//   b
//   a

Parameters

• eventName: string | symbol

The name of the event.

• listener: (...args) => void

The callback function

Returns

this

Inherited from

Service.once

Since

v0.3.0

Source

otel/node_modules/@types/node/events.d.ts:607

patch()

patch(): void

Patch all services to add span

Returns

void

Source

otel/src/otel.ts:220

prependListener()

prependListener(eventName, listener): 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 eventNameand 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.

Parameters

• eventName: string | symbol

The name of the event.

• listener: (...args) => void

The callback function

Returns

this

Inherited from

Service.prependListener

Since

v6.0.0

Source

otel/node_modules/@types/node/events.d.ts:834

prependOnceListener()

prependOnceListener(eventName, listener): this

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.

Parameters

• eventName: string | symbol

The name of the event.

• listener: (...args) => void

The callback function

Returns

this

Inherited from

Service.prependOnceListener

Since

v6.0.0

Source

otel/node_modules/@types/node/events.d.ts:850

rawListeners()

rawListeners(eventName): Function[]

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');

Parameters

• eventName: string | symbol

Returns

Function[]

Inherited from

Service.rawListeners

Since

v9.4.0

Source

otel/node_modules/@types/node/events.d.ts:766

reinit()

reinit(config): Promise<OtelService<T>>

Allow to reinit the service

Parameters

• config: DeepPartial<T>

Returns

Promise<OtelService<T>>

Overrides

Service.reinit

Source

otel/src/otel.ts:177

removeAllListeners()

removeAllListeners(event?): this

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

• event?: string | symbol

Returns

this

Inherited from

Service.removeAllListeners

Since

v0.1.26

Source

otel/node_modules/@types/node/events.d.ts:706

removeListener()

removeListener(eventName, listener): this

Removes the specified listener from the listener array for the event namedeventName.

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 anyremoveListener() 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.

Parameters

• eventName: string | symbol

• listener: (...args) => void

Returns

this

Inherited from

Service.removeListener

Since

v0.1.26

Source

otel/node_modules/@types/node/events.d.ts:690

resolve()

resolve(): OtelService<T>

Returns

OtelService<T>

Overrides

Service.resolve

Source

otel/src/otel.ts:119

setMaxListeners()

setMaxListeners(n): this

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 toInfinity (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

Inherited from

Service.setMaxListeners

Since

v0.3.5

Source

otel/node_modules/@types/node/events.d.ts:716

stop()

stop(): Promise<void>

Returns

Promise<void>

Overrides

Service.stop

Source

otel/src/otel.ts:90

toJSON()

toJSON(): string

Prevent service to be serialized

Returns

string

Inherited from

Service.toJSON

Source

core/lib/services/service.d.ts:268

toPublicJSON()

toPublicJSON(object): string

Convert an object to JSON using the Webda json filter

Parameters

• object: unknown

The object to export

Returns

string

The export of the strip object ( removed all attribute with _ )

Inherited from

Service.toPublicJSON

Source

core/lib/services/service.d.ts:263

toString()

toString(): string

Return service representation

Returns

string

Inherited from

Service.toString

Source

core/lib/services/service.d.ts:192

unpatch()

unpatch(): void

Remove patched methods

Returns

void

Source

otel/src/otel.ts:191

addAbortListener()

Experimental

static addAbortListener(signal, resource): Disposable

Listens once to the abort event on the provided signal.

Listening to the abort event on abort signals is unsafe and may lead to resource leaks since another third party with the signal can call e.stopImmediatePropagation(). Unfortunately Node.js cannot change this since it would violate the web standard. Additionally, the original API makes it easy to forget to remove listeners.

This API allows safely using AbortSignals in Node.js APIs by solving these two issues by listening to the event such that stopImmediatePropagation does not prevent the listener from running.

Returns a disposable so that it may be unsubscribed from more easily.

import { addAbortListener } from 'node:events';

function example(signal) {
  let disposable;
  try {
    signal.addEventListener('abort', (e) => e.stopImmediatePropagation());
    disposable = addAbortListener(signal, (e) => {
      // Do something when signal is aborted.
    });
  } finally {
    disposable?.[Symbol.dispose]();
  }
}

Parameters

• signal: AbortSignal

• resource: (event) => void

Returns

Disposable

Disposable that removes the abort listener.

Inherited from

Service.addAbortListener

Since

v20.5.0

Source

otel/node_modules/@types/node/events.d.ts:387

getEventListeners()

static getEventListeners(emitter, name): Function[]

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

For EventEmitters this behaves exactly the same as calling .listeners on the emitter.

For EventTargets this is the only way to get the event listeners for the event target. This is useful for debugging and diagnostic purposes.

import { getEventListeners, EventEmitter } from 'node:events';

{
  const ee = new EventEmitter();
  const listener = () => console.log('Events are fun');
  ee.on('foo', listener);
  console.log(getEventListeners(ee, 'foo')); // [ [Function: listener] ]
}
{
  const et = new EventTarget();
  const listener = () => console.log('Events are fun');
  et.addEventListener('foo', listener);
  console.log(getEventListeners(et, 'foo')); // [ [Function: listener] ]
}

Parameters

• emitter: EventEmitter | _DOMEventTarget

• name: string | symbol

Returns

Function[]

Inherited from

Service.getEventListeners

Since

v15.2.0, v14.17.0

Source

otel/node_modules/@types/node/events.d.ts:308

getMaxListeners()

static getMaxListeners(emitter): number

Returns the currently set max amount of listeners.

For EventEmitters this behaves exactly the same as calling .getMaxListeners on the emitter.

For EventTargets this is the only way to get the max event listeners for the event target. If the number of event handlers on a single EventTarget exceeds the max set, the EventTarget will print a warning.

import { getMaxListeners, setMaxListeners, EventEmitter } from 'node:events';

{
  const ee = new EventEmitter();
  console.log(getMaxListeners(ee)); // 10
  setMaxListeners(11, ee);
  console.log(getMaxListeners(ee)); // 11
}
{
  const et = new EventTarget();
  console.log(getMaxListeners(et)); // 10
  setMaxListeners(11, et);
  console.log(getMaxListeners(et)); // 11
}

Parameters

• emitter: EventEmitter | _DOMEventTarget

Returns

number

Inherited from

Service.getMaxListeners

Since

v19.9.0

Source

otel/node_modules/@types/node/events.d.ts:337

listenerCount()

static listenerCount(emitter, eventName): number

A class method that returns the number of listeners for the given eventNameregistered on the given emitter.

import { EventEmitter, listenerCount } from 'node:events';

const myEmitter = new EventEmitter();
myEmitter.on('event', () => {});
myEmitter.on('event', () => {});
console.log(listenerCount(myEmitter, 'event'));
// Prints: 2

Parameters

• emitter: EventEmitter

The emitter to query

• eventName: string | symbol

The event name

Returns

number

Inherited from

Service.listenerCount

Since

v0.9.12

Deprecated

Since v3.2.0 - Use listenerCount instead.

Source

otel/node_modules/@types/node/events.d.ts:280

on()

static on(emitter, eventName, options?): AsyncIterableIterator<any>

import { on, EventEmitter } from 'node:events';
import process from 'node:process';

const ee = new EventEmitter();

// Emit later on
process.nextTick(() => {
  ee.emit('foo', 'bar');
  ee.emit('foo', 42);
});

for await (const event of on(ee, 'foo')) {
  // The execution of this inner block is synchronous and it
  // processes one event at a time (even with await). Do not use
  // if concurrent execution is required.
  console.log(event); // prints ['bar'] [42]
}
// Unreachable here

Returns an AsyncIterator that iterates eventName events. It will throw if the EventEmitter emits 'error'. It removes all listeners when exiting the loop. The value returned by each iteration is an array composed of the emitted event arguments.

An AbortSignal can be used to cancel waiting on events:

import { on, EventEmitter } from 'node:events';
import process from 'node:process';

const ac = new AbortController();

(async () => {
  const ee = new EventEmitter();

  // Emit later on
  process.nextTick(() => {
    ee.emit('foo', 'bar');
    ee.emit('foo', 42);
  });

  for await (const event of on(ee, 'foo', { signal: ac.signal })) {
    // The execution of this inner block is synchronous and it
    // processes one event at a time (even with await). Do not use
    // if concurrent execution is required.
    console.log(event); // prints ['bar'] [42]
  }
  // Unreachable here
})();

process.nextTick(() => ac.abort());

Parameters

• emitter: EventEmitter

• eventName: string

The name of the event being listened for

• options?: StaticEventEmitterOptions

Returns

AsyncIterableIterator<any>

that iterates eventName events emitted by the emitter

Inherited from

Service.on

Since

v13.6.0, v12.16.0

Source

otel/node_modules/@types/node/events.d.ts:258

once()

once(emitter, eventName, options)

static once(emitter, eventName, options?): Promise<any[]>

Creates a Promise that is fulfilled when the EventEmitter emits the given event or that is rejected if the EventEmitter emits 'error' while waiting. The Promise will resolve with an array of all the arguments emitted to the given event.

This method is intentionally generic and works with the web platform EventTarget interface, which has no special'error' event semantics and does not listen to the 'error' event.

import { once, EventEmitter } from 'node:events';
import process from 'node:process';

const ee = new EventEmitter();

process.nextTick(() => {
  ee.emit('myevent', 42);
});

const [value] = await once(ee, 'myevent');
console.log(value);

const err = new Error('kaboom');
process.nextTick(() => {
  ee.emit('error', err);
});

try {
  await once(ee, 'myevent');
} catch (err) {
  console.error('error happened', err);
}

The special handling of the 'error' event is only used when events.once()is used to wait for another event. If events.once() is used to wait for the 'error' event itself, then it is treated as any other kind of event without special handling:

import { EventEmitter, once } from 'node:events';

const ee = new EventEmitter();

once(ee, 'error')
  .then(([err]) => console.log('ok', err.message))
  .catch((err) => console.error('error', err.message));

ee.emit('error', new Error('boom'));

// Prints: ok boom

An AbortSignal can be used to cancel waiting for the event:

import { EventEmitter, once } from 'node:events';

const ee = new EventEmitter();
const ac = new AbortController();

async function foo(emitter, event, signal) {
  try {
    await once(emitter, event, { signal });
    console.log('event emitted!');
  } catch (error) {
    if (error.name === 'AbortError') {
      console.error('Waiting for the event was canceled!');
    } else {
      console.error('There was an error', error.message);
    }
  }
}

foo(ee, 'foo', ac.signal);
ac.abort(); // Abort waiting for the event
ee.emit('foo'); // Prints: Waiting for the event was canceled!

Parameters

• emitter: _NodeEventTarget

• eventName: string | symbol

• options?: StaticEventEmitterOptions

Returns

Promise<any[]>

Inherited from

Service.once

Since

v11.13.0, v10.16.0

Source

otel/node_modules/@types/node/events.d.ts:193

once(emitter, eventName, options)

static once(emitter, eventName, options?): Promise<any[]>

Parameters

• emitter: _DOMEventTarget

• eventName: string

• options?: StaticEventEmitterOptions

Returns

Promise<any[]>

Inherited from

Service.once

Source

otel/node_modules/@types/node/events.d.ts:198

setMaxListeners()

static setMaxListeners(n?, ...eventTargets?): void

import { setMaxListeners, EventEmitter } from 'node:events';

const target = new EventTarget();
const emitter = new EventEmitter();

setMaxListeners(5, target, emitter);

Parameters

• n?: number

A non-negative number. The maximum number of listeners per EventTarget event.

• ...eventTargets?: (EventEmitter | _DOMEventTarget)[]

Returns

void

Inherited from

Service.setMaxListeners

Since

v15.4.0

Source

otel/node_modules/@types/node/events.d.ts:352

Class: OtelService<T>

Webda Modda​

Extends​

Type parameters​

Constructors​

new OtelService(webda, name, params)​

Parameters​

Returns​

Inherited from​

Source​

Properties​

_createException​

Inherited from​

Source​

_initException​

Inherited from​

Source​

_initTime​

Inherited from​

Source​

_name​

Inherited from​

Source​

_webda​

Inherited from​

Source​

logger​

Inherited from​

Source​

loggerExporter​

Source​

loggerProvider​

Source​

metrics?​

Inherited from​

Source​

otelLogger​

Source​

parameters​

Inherited from​

Source​

sdk​

Source​

stubs​

Source​

wrapper​

Source​

captureRejectionSymbol​

Since​

Inherited from​

Source​

captureRejections​

Since​

Inherited from​

Source​

defaultMaxListeners​

Since​

Inherited from​

Source​

errorMonitor​

Since​

Inherited from​

Source​

Methods​

[captureRejectionSymbol]()?​

Parameters​

Returns​

Inherited from​

Source​

__clean()​

Returns​

Inherited from​

Abstract​

Source​

_wrap()​

Parameters​

Returns​

Source​

addListener()​

Parameters​

Webda Modda

Extends

Type parameters

Constructors

new OtelService(webda, name, params)

Parameters

Returns

Inherited from

Source

Properties

_createException

Inherited from

Source

_initException

Inherited from

Source

_initTime

Inherited from

Source

_name

Inherited from

Source

_webda

Inherited from

Source

logger

Inherited from

Source

loggerExporter

Source

loggerProvider

Source

metrics?

Inherited from

Source

otelLogger

Source

parameters

Inherited from

Source

sdk

Source

stubs

Source

wrapper

Source

captureRejectionSymbol

Since

Inherited from

Source

captureRejections

Since

Inherited from

Source

defaultMaxListeners

Since

Inherited from

Source

errorMonitor

Since

Inherited from

Source

Methods

`[captureRejectionSymbol]`()?

Parameters

Returns

Inherited from

Source

__clean()

Returns

Inherited from

Abstract

Source

_wrap()

Parameters

Returns

Source

addListener()

Parameters

Returns