EventBus

@delta-base/server

---

Class: EventBus

EventBus client for managing subscriptions to an event store

Constructors

Constructor

new EventBus(http, eventStoreName): EventBus

Create a new EventBus client for a specific event store

Parameters

http

HttpClient

The HTTP client used for API requests

eventStoreName

string

The name of the event store to manage subscriptions for

Returns

EventBus

Methods

getSubscription()

getSubscription(subscriberId): Promise<Subscription>

Get details about a specific subscription

Parameters

subscriberId

string

ID of the subscription to retrieve

Returns

Promise<Subscription>

Subscription details

Example

const subscription = await eventBus.getSubscription('sub_123456');
console.log(subscription.status); // 'ACTIVE'

---

listSubscriptions()

listSubscriptions(options): Promise<ListSubscriptionsResponse>

List all subscriptions for this event store

Parameters

options

ListSubscriptionsOptions = {}

Optional filtering and pagination parameters

Returns

Promise<ListSubscriptionsResponse>

List of subscriptions and total count

Example

// List all webhook subscriptions
const { subscriptions, totalCount } = await eventBus.listSubscriptions({
  subscriberType: SubscriberType.Webhook,
  limit: 20,
  offset: 0
});

---

subscribe()

subscribe(options): Promise<Subscription>

Subscribe to events from this event store

Parameters

options

SubscribeOptions

Configuration for the subscription

Returns

Promise<Subscription>

The created subscription information

Throws

When subscription configuration is invalid

Throws

When the event store doesn’t exist

Throws

When request validation fails

Throws

When authentication fails

Example

import {
  isInvalidSubscriptionConfigError,
  isEventStoreNotFoundError
} from '@delta-base/server';

try {
  const subscription = await eventBus.subscribe({
    eventFilter: 'user.*',
    subscriber: {
      type: SubscriberType.Webhook,
      config: {
        url: 'https://example.com/webhook',
        headers: { 'X-API-Key': 'secret' },
        retryPolicy: {
          maxAttempts: 3,
          backoffMinutes: 5
        }
      }
    }
  });

  // Check if this is an existing subscription
  if (subscription.isExistingSubscription) {
    console.log('Found existing subscription:', subscription.message);
  } else {
    console.log('Created new subscription:', subscription.message);
  }
} catch (error) {
  if (isInvalidSubscriptionConfigError(error)) {
    console.log(`Invalid configuration: ${error.configError}`);
    // Handle invalid subscription config
  } else if (isEventStoreNotFoundError(error)) {
    console.log(`Event store '${error.eventStoreId}' not found`);
    // Handle missing event store
  } else {
    throw error; // Re-throw unknown errors
  }
}

---

subscribeWebhook()

subscribeWebhook(eventFilter, url, options): Promise<Subscription>

Create a webhook subscription

Parameters

eventFilter

EventFilterPattern

Pattern determining which events to receive

url

string

The URL that will receive HTTP POST requests with events

options

Omit<WebhookConfig, "url"> & object = {}

Additional configuration options

Returns

Promise<Subscription>

The created subscription information

Example

// Subscribe to all user events
const subscription = await eventBus.subscribeWebhook(
  'user.*',
  'https://example.com/webhook',
  {
    headers: { 'X-API-Key': 'secret' },
    retryPolicy: {
      maxAttempts: 3,
      backoffMinutes: 5
    }
  }
);

// Check if this is an existing subscription with the same configuration
if (subscription.isExistingSubscription) {
  console.log('Reusing existing subscription:', subscription.message);
} else {
  console.log('Created new subscription:', subscription.message);
}

---

unsubscribe()

unsubscribe(subscriberId): Promise<{ message: string; success: boolean; }>

Unsubscribe from events (delete a subscription)

Parameters

subscriberId

string

ID of the subscription to delete

Returns

Promise<{ message: string; success: boolean; }>

Success message

Example

const result = await eventBus.unsubscribe('sub_123456');
console.log(result.success); // true

---

updateSubscription()

updateSubscription(subscriberId, options): Promise<Subscription>

Update an existing subscription (partial update)

Only the fields you provide will be changed. You must provide at least one field.

Parameters

subscriberId

string

ID of the subscription to update

options

UpdateSubscriptionOptions

Fields to update

Returns

Promise<Subscription>

The updated subscription

Throws

When the subscription doesn’t exist

Throws

When the update payload is invalid

Throws

When request validation fails

Example

// Pause a subscription
const updated = await eventBus.updateSubscription('sub_123456', {
  status: 'SUSPENDED',
});

// Change the event filter and retry policy
const updated = await eventBus.updateSubscription('sub_123456', {
  eventFilter: 'order.*',
  retryPolicy: {
    maxAttempts: 5,
    strategy: 'exponential',
    initialDelayMs: 1000,
    maxDelayMs: 60000,
  },
});