EventBus

@delta-base/server

---

Class: EventBus

EventBus client for managing subscriptions to an event store

Constructors

Constructor

new EventBus(http, eventStoreId): EventBus

Create a new EventBus client for a specific event store

Parameters

http

HttpClient

The HTTP client used for API requests

eventStoreId

string

The ID of the event store to manage subscriptions for

Returns

EventBus

Methods

getSubscription()

getSubscription(subscriptionId): Promise<Subscription>

Get details about a specific subscription

Parameters

subscriptionId

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

Unsubscribe from events (delete a subscription)

Parameters

subscriptionId

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