Transports

Transports are the low-level channel implementations that move messages between contexts (tabs, iframes, workers). PubSub MFE provides a flexible adapter layer so you can choose the best transport for your application environment.

Transport Types

• BroadcastChannel — fastest and simplest for modern browsers.
• SharedWorker — robust, centralized broker for multiple tabs (good for heavy workloads).
• LocalStorage / postMessage — compatibility fallbacks for older browsers.
• Auto — a smart transport that selects the best available option and falls back gracefully.

Choosing a Transport

• Prefer BroadcastChannel when available — low latency, simple API.
• Use SharedWorker when you need a centralized broker and more control over message flow and batching.
• Use Auto for libraries that need broad compatibility; it selects the best supported transport at runtime.

Example: Using a Transport Directly

import { createPubSub } from '@belyas/pubsub-mfe';
import {
  createBroadcastChannelTransport
} from '@belyas/pubsub-mfe/adapters/cross-tab/transports/broadcast-channel';

const bus = createPubSub();

const transport = createBroadcastChannelTransport({ channelName: 'my-app' });

// Attach transport to an adapter (if using the cross-tab adapter)
// Most apps use the cross-tab adapter rather than managing transports directly

Transport Configuration Options

Typical transport options include:

• channelName — unique name for your app channel
• debug?: boolean; — enable debugging mode
• onError?: (error: Error) => void | undefined; — erorr handling

Reliability & Deduplication

Transports should implement deduplication and ordering where possible. The adapters in PubSub MFE add an extra deduplication layer to protect against duplicate delivery across transports.

Security Considerations

• Transports may expose messages to other origins or frames; validate and filter messages at the adapter boundary.
• Use meta.source and optional signing at boundaries when communicating with untrusted frames or third-party scripts.

See also: Cross-Tab Adapter and Performance Benchmarks.