Transport Overview

The Four Transports

Default Recommendation

For BizFirstGO browser applications connecting to ASP.NET Core SignalR hubs, use 'signalr'. It handles WebSocket, SSE, and long-polling fallback internally so you do not need to configure fallbacks manually:

stream.registerServer({
  id: 'bas',
  type: 'bas',
  url: '/hubs/edge-stream',
  transportConfig: {
    type: 'signalr',
    url: '/hubs/edge-stream',
    accessToken: () => authStore.getToken(),
  }
});

ITransport Interface

Every transport implements the same interface. This is how EdgeStream remains transport-agnostic:

interface ITransport {
  readonly id: string;
  readonly type: 'signalr' | 'websocket' | 'sse' | 'http-polling';
  readonly status: TransportStatus;  // 'disconnected' | 'connecting' | 'connected' | 'reconnecting' | 'error'
  readonly lastError?: Error;

  connect(): Promise<void>;
  disconnect(): Promise<void>;
  send(data: string | ArrayBuffer): Promise<void>;

  onMessage(handler: (raw: string | ArrayBuffer) => void): () => void;
  onStatusChange(handler: (status: TransportStatus) => void): () => void;
  onError(handler: (error: Error) => void): () => void;
}

Auto-Detection

createAutoTransport() picks the best available transport for the current environment:

import { createAutoTransport, detectBestTransport } from 'edge-stream-js';

// Detect without creating
const type = detectBestTransport();
// 'websocket' if WebSocket supported, 'sse' if EventSource supported, 'http-polling' fallback

// Create with auto-detection
const transport = createAutoTransport('wss://example.com/ws');

// Create with preferred type (falls back if unavailable)
const preferred = createAutoTransport('wss://example.com/ws', 'websocket');

Transport Status Values