SSEConnection

Defined in: packages/core/src/data/streaming/sse-connection.ts:76

Server-Sent Events connection.

Remarks

Primary streaming mechanism for real-time updates. Uses the native EventSource API for robust, automatic reconnection handling.

Features:

• Automatic reconnection by the browser
• Event-based message streaming
• JSON message parsing with error handling
• Multiple event type support
• Last event ID tracking for resume

Example

const sse = new SSEConnection({
  url: 'https://api.example.com/events',
  eventTypes: ['update', 'delete'],
});

sse.on('message', ({ data }) => {
  console.log('Received:', data);
});

sse.on('error', ({ error }) => {
  console.error('Error:', error);
});

await sse.connect();

Extends

• BaseConnection

Constructors

Constructor

new SSEConnection(config): SSEConnection

Defined in: packages/core/src/data/streaming/sse-connection.ts:95

Create a new SSE connection.

Parameters

Parameter	Type	Description
config	SSEConfig	SSE configuration

Returns

SSEConnection

Example

const connection = new SSEConnection({
  url: 'https://api.example.com/stream',
  eventTypes: ['message', 'update'],
  withCredentials: true,
});

Overrides

BaseConnection.constructor

Methods

connect()

connect(): Promise<void>

Defined in: packages/core/src/data/streaming/sse-connection.ts:125

Establish SSE connection.

Returns

Promise<void>

Remarks

Creates an EventSource and sets up event listeners for:

• Connection open
• Message events (for each configured event type)
• Error events

The EventSource API handles reconnection automatically when the connection is lost, unless explicitly closed.

Throws

Error if EventSource is not supported or connection fails

Example

await connection.connect();
console.log('Connected to SSE stream');

Overrides

BaseConnection.connect

---

disconnect()

disconnect(): void

Defined in: packages/core/src/data/streaming/sse-connection.ts:190

Close SSE connection.

Returns

void

Remarks

Closes the EventSource and cleans up all event listeners. Sets the manual disconnect flag to prevent automatic reconnection.

Example

connection.disconnect();
console.log('Disconnected from SSE stream');

Overrides

BaseConnection.disconnect

---

eventNames()

eventNames(): keyof ConnectionEvents[]

Defined in: packages/core/src/utils/event-emitter.ts:211

Get all event names that have registered handlers

Returns

keyof ConnectionEvents[]

Array of event names

Example

const events = emitter.eventNames();
console.log('Events with handlers:', events);

Inherited from

BaseConnection.eventNames

---

getLastEventId()

getLastEventId(): string | null

Defined in: packages/core/src/data/streaming/sse-connection.ts:214

Get the last event ID received from the server.

Returns

string | null

Last event ID or null if none received

Remarks

The event ID is used by the EventSource API to resume the stream from the last received event after a reconnection. The browser automatically sends this ID in the Last-Event-ID header.

Example

const lastId = connection.getLastEventId();
if (lastId) {
  console.log(`Last event: ${lastId}`);
}

---

getReconnectAttempts()

getReconnectAttempts(): number

Defined in: packages/core/src/data/streaming/base-connection.ts:200

Get the number of reconnection attempts.

Returns

number

Number of reconnect attempts

Inherited from

BaseConnection.getReconnectAttempts

---

getState()

getState(): ConnectionState

Defined in: packages/core/src/data/streaming/base-connection.ts:175

Get current connection state.

Returns

ConnectionState

Current state

Example

const state = connection.getState();
if (state === 'connected') {
  // Connection is ready
}

Inherited from

BaseConnection.getState

---

hasListeners()

hasListeners<K>(event): boolean

Defined in: packages/core/src/utils/event-emitter.ts:228

Check if an event has any registered handlers

Type Parameters

Type Parameter
K extends keyof ConnectionEvents

Parameters

Parameter	Type	Description
event	K	Event name

Returns

boolean

True if the event has at least one handler

Example

if (emitter.hasListeners('message')) {
  emitter.emit('message', { text: 'Hello' });
}

Inherited from

BaseConnection.hasListeners

---

isConnected()

isConnected(): boolean

Defined in: packages/core/src/data/streaming/base-connection.ts:191

Check if connection is currently connected.

Returns

boolean

True if connected

Example

if (connection.isConnected()) {
  connection.send(data);
}

Inherited from

BaseConnection.isConnected

---

listenerCount()

listenerCount<K>(event): number

Defined in: packages/core/src/utils/event-emitter.ts:195

Get the number of handlers registered for an event

Type Parameters

Type Parameter
K extends keyof ConnectionEvents

Parameters

Parameter	Type	Description
event	K	Event name

Returns

number

Number of registered handlers

Example

const count = emitter.listenerCount('message');
console.log(`${count} handlers registered`);

Inherited from

BaseConnection.listenerCount

---

off()

off<K>(event, handler): void

Defined in: packages/core/src/utils/event-emitter.ts:120

Remove an event handler

Type Parameters

Type Parameter
K extends keyof ConnectionEvents

Parameters

Parameter	Type	Description
event	K	Event name
handler	EventHandler<ConnectionEvents[K]>	Handler function to remove

Returns

void

Example

const handler = (data) => console.log(data);
emitter.on('message', handler);
emitter.off('message', handler);

Inherited from

BaseConnection.off

---

on()

on<K>(event, handler): () => void

Defined in: packages/core/src/utils/event-emitter.ts:65

Register an event handler

Type Parameters

Type Parameter
K extends keyof ConnectionEvents

Parameters

Parameter	Type	Description
event	K	Event name to listen for
handler	EventHandler<ConnectionEvents[K]>	Callback function to invoke when event is emitted

Returns

Unsubscribe function that removes this specific handler

() => void

Example

const unsubscribe = emitter.on('message', (data) => {
  console.log(data.text);
});

// Later, to unsubscribe:
unsubscribe();

Inherited from

BaseConnection.on

---

once()

once<K>(event, handler): void

Defined in: packages/core/src/utils/event-emitter.ts:95

Register a one-time event handler

Type Parameters

Type Parameter
K extends keyof ConnectionEvents

Parameters

Parameter	Type	Description
event	K	Event name to listen for
handler	EventHandler<ConnectionEvents[K]>	Callback function to invoke once

Returns

void

Remarks

The handler will be automatically removed after being invoked once.

Example

emitter.once('connect', () => {
  console.log('Connected!');
});

Inherited from

BaseConnection.once

---

removeAllListeners()

removeAllListeners<K>(event?): void

Defined in: packages/core/src/utils/event-emitter.ts:175

Remove all handlers for an event, or all handlers for all events

Type Parameters

Type Parameter
K extends keyof ConnectionEvents

Parameters

Parameter	Type	Description
event?	K	Optional event name. If omitted, removes all handlers for all events.

Returns

void

Example

// Remove all handlers for 'message' event
emitter.removeAllListeners('message');

// Remove all handlers for all events
emitter.removeAllListeners();

Inherited from

BaseConnection.removeAllListeners