Class HttpRelayTransport

endpoints/js-agent/src/transport/relay.ts:72–200

 * ACK/COK responses in the HTTP response body.
 */
export class HttpRelayTransport {
  // relayUrl, clusterId, and timeoutMs are always populated (default
  // applied below for timeoutMs); logger remains optional.
  private readonly config: {
    relayUrl: string;
    clusterId: string;
    timeoutMs: number;
    logger?: Logger;
  };
  private readonly eventHandlers: Map<TransportEvent, Set<EventHandler>> = new Map();
  private readonly log: Logger;
  private connected = false;

  constructor(config: HttpRelayTransportConfig) {
    if (!config.clusterId) {
      // Fail loudly at construction time. A late 400 from the relay is
      // harder to diagnose than an Error here pointing at the source.
      throw new Error('[HttpRelayTransport] clusterId is required');
    }
    this.config = {
      timeoutMs: 10_000,
      ...config,
    };
    this.log = config.logger ?? noopLogger;
  }

  // ─── Transport interface ──────────────────────────────────────────────────

  /** Always resolves immediately — no persistent connection needed. */
  async connect(): Promise<void> {
    this.connected = true;
    // Emit 'open' asynchronously so callers can attach handlers after connect().
    setTimeout(() => this.emit('open', undefined), 0);
  }

  /** Marks the transport as disconnected. */
  disconnect(): void {
    this.connected = false;
    this.emit('close', undefined);
  }

  /** Returns true if connect() has been called and disconnect() has not. */
  isConnected(): boolean {
    return this.connected;
  }

  /**
   * Sends an NHP packet to the relay and delivers the response via the
   * 'message' event.
   *
   * @throws Error if the relay returns a non-200 status or the request times
   *         out.
   */
  async send(data: Uint8Array): Promise<void> {
    if (!this.connected) {
      throw new Error('[HttpRelayTransport] not connected');
    }