API Reference

Complete constructor properties, method signatures, middleware chains, error tables, and TypeScript definitions for AfterLink.

API Directory Mapping

• Server Constructor Options • server.on() method • server.use() middleware • server.publish() pub/sub • server.broadcast() fan-out • server.close() shutdown • @ajaymyth/cluster Package • Metrics & Observability • Client Constructor Options • client.connect() / disconnect() • client.request() RPC loops • client.subscribe() channels • client.publish() streams • client.stream() chunks • Python & Dart SDKs • Protocol Error Codes • TypeScript Types Reference

Server Class Reference

Instantiated via new Server(options) or the wrapper helper createServer(options).

Server Options Parameters

Option	Type	Default	Description
port	number	8080	TCP port configuration range.
host	string	'0.0.0.0'	Network interface address mapping.
idleTimeout	number	60000	Heartbeat delay threshold in milliseconds.
maxConnections	number	10000	Peak concurrent active sockets allowance limits.
tls	object	null	Pass key, cert buffers to activate secure TLS handshakes.
metrics	object	null	Enable Prometheus endpoint and set custom port/path options.
tracing	TracingManager	null	OpenTelemetry-compliant context propagation instance.

server.on() method

Callback Hooks

Registers a callback listener for specific route requests or system handshake events, optionally verifying with Zod validation models.

Signature

server.on(route: string, handler: (socket, payload) => void, schema?: ZodSchema)

server.use() method

Middleware

Injects global middleware functions into the connection processing stack (e.g. JWT validations or packet logging).

Signature

server.use(middleware: (socket, frame, next) => void)

server.publish() method

Pub/Sub

Pushes pub/sub broadcasts directly onto channel topics. Server manages delivery lists and relays MSG_BROADCAST (0x05) frames automatically.

Signature

server.publish(channel: string, payload: any)

server.broadcast() method

Fan-Out

Transmits identical raw payload buffers to all active client sockets regardless of routing channel configurations.

Signature

server.broadcast(type: string, payload: any)

server.close() method

Shutdown

Closes raw TCP bindings gracefully, terminating keepalive heartbeats, and closing active connections correctly.

Signature

server.close(callback?: () => void): Promise<void>

@ajaymyth/cluster Package Reference

Instantiated via new ClusterManager(options) to manage worker process forks, Redis-backed shared pub/sub routing, worker crash detection/restarts, and SIGUSR2 rolling restarts.

ClusterManager Options

Option	Type	Default	Description
workers	number \| 'auto'	'auto'	Number of worker processes to fork (defaults to CPU core count).
redis	string \| object	'redis://127.0.0.1:6379'	Redis connection URL or Redis.Cluster node array for multi-node routing.
autoRestart	boolean	true	Automatically fork new worker process on worker crash.
rollingRestart	boolean	true	Enable zero-downtime rolling restarts on SIGUSR2 process signals.

ClusterManager API class

Node Clustering

Initializes worker clusters with automatic load distribution across primary TCP sockets and synchronizes pub/sub state across node boundaries via Redis pub/sub.

Usage Signature

import { ClusterManager } from '@ajaymyth/cluster';

const cluster = new ClusterManager({
  workers: 'auto',
  redis: { nodes: ['10.0.0.1:6379', '10.0.0.2:6379'] }
});

cluster.start();

Metrics & Observability Reference

AfterLink v2 includes built-in Prometheus metric collection and OpenTelemetry tracing propagation via AsyncLocalStorage.

Prometheus & OTel Tracing observability

Telemetry

Configuring metrics exposes HTTP endpoints for Prometheus scrapers (e.g. /__metrics) and provides Grafana dashboard templates. The TracingManager propagates trace IDs across binary frame headers using AsyncLocalStorage context.

Configuration Signature

import { Server, TracingManager } from '@ajaymyth/server';

const tracing = new TracingManager({ serviceName: 'order-service' });
const server = new Server({
  port: 8080,
  metrics: { enabled: true, port: 9090, path: '/metrics' },
  tracing
});

Client Class Reference

Instantiated via new Client(options) or the wrapper helper createClient(options).

Client Options Parameters

Option	Type	Default	Description
host	string	'127.0.0.1'	Host address of target AfterLink server.
port	number	8080	Destination binding TCP port range.
autoReconnect	boolean	true	Triggers socket re-connections upon socket drops.
maxRetries	number	10	Limits reconnection sequences before throwing errors.

client.connect() / disconnect() method

Connection Lifecycle

Triggers asynchronous handshakes to establish active socket bindings, or tears down established socket connections gracefully.

Signature

client.connect(): Promise<void>  |  client.disconnect(): Promise<void>

client.request() method

RPC Loop

Dispatches structured RPC request packets (MSG_REQUEST) and returns matching Promise response elements resolving when server returns matching seq IDs.

Signature

client.request(route: string, body: any, options?: object): Promise<any>

client.subscribe() method

Pub/Sub

Binds call functions to specific pub/sub streams. Instructs server routing layers by pushing MSG_SUBSCRIBE frames immediately.

Signature

client.subscribe(channel: string, callback: (payload, channel) => void): void

client.publish() method

Pub/Sub

Publishes messages onto specified routing channels. Packages fields and transmits a single MSG_PUBLISH (0x03) packet.

Signature

client.publish(channel: string, payload: any): void

client.stream() method

Streaming

Establishes interactive, multi-frame streaming pipelines. Dispatches structured MSG_STREAM packets sequentially and ends with a MSG_STREAM_END marker.

Signature

client.stream(route: string, body: any): Promise<ReadableStream>

Python & Dart SDK API Reference

AfterLink v2 provides native Python and Dart client & server SDKs matching the 16-byte Protocol v2 header layout.

Python SDK (PyPI: afterlink) Python 3.8+

Provides AsyncServer, AsyncClient, and SyncClient wrapper with full type hints and Pydantic validation support.

from afterlink import AsyncClient

client = AsyncClient(host="127.0.0.1", port=8080)
await client.connect()

# RPC with priority queue & routing key
response = await client.request(
    "users.get",
    {"id": 42},
    priority=7,
    routing_key="users"
)

Dart SDK (pub.dev: afterlink) Dart 3.0+

Supports native TCP and web WebSocket transports with conditional compilation loaders and standard MessagePack serialization.

import 'package:afterlink/afterlink.dart';

final client = AfterLinkClient(host: '127.0.0.1', port: 8080);
await client.connect();

// Pub/sub with priority level
client.publish(
  'chat.global',
  {'text': 'Hello Dart!'},
  priority: 5,
);

Protocol Error Codes

Error Code	Error Constant	Diagnostic Description & Root Cause
100	ERR_MAGIC_MISMATCH	Invalid magic identifier bytes. Sockets from hostile scans or HTTP requests.
101	ERR_VERSION_UNSUPPORTED	The client version constant is incompatible with this server.
400	ERR_BAD_FRAME	Corrupt framing format structure, 16-byte header or length offsets mismatch.
401	ERR_UNAUTHORIZED	Missing, invalid or expired handshake JWT authentication tokens.
404	ERR_ROUTE_NOT_FOUND	No matching method path listener exists on this server.
422	ERR_VALIDATION_FAILED	The frame payload model does not conform to the registered Zod/Pydantic validation schema.
429	ERR_RATE_LIMITED	Connection request counts exceeded maximum specified configurations.
500	ERR_INTERNAL_SERVER	Unhandled exception occurred in server-side handler code.

TypeScript Declarations

Full TypeScript definitions for the core interfaces:

← Protocol Specification Pub/Sub System →