http

Overview ¶

Package http provides utilities for HTTP request handling and production-grade WebSocket connections.

This package contains two main areas of functionality:

1. HTTP utilities for simplified request/response handling
2. WebSocket abstractions built on Gorilla WebSocket for real-time applications

WebSocket Framework ¶

The WebSocket framework provides a production-ready abstraction over Gorilla WebSocket with automatic connection management, heartbeat detection, and lifecycle hooks.

## Key Features

• Production-grade connection management with automatic heartbeat detection
• Lifecycle hooks for connection start, close, timeout, and error handling
• Thread-safe message broadcasting to multiple clients
• Automatic ping-pong mechanism to prevent connection timeouts
• Type-safe message handling with Go generics
• Built-in JSON message support with JSONConn
• Configurable timeouts and intervals for different deployment scenarios

## Quick Start

The simplest way to create a WebSocket endpoint is using the built-in JSONConn:

type EchoConn struct {
	gohttp.JSONConn
}

func (e *EchoConn) HandleMessage(msg any) error {
	// Echo the message back to the client
	e.Writer.Send(conc.Message[any]{Value: msg})
	return nil
}

type EchoHandler struct{}

func (h *EchoHandler) Validate(w http.ResponseWriter, r *http.Request) (*EchoConn, bool) {
	return &EchoConn{}, true // Accept all connections
}

// Register with HTTP router
router.HandleFunc("/echo", gohttp.WSServe(&EchoHandler{}, nil))

## Architecture

The framework uses three main interfaces:

### WSConn[I any] Represents a WebSocket connection that can handle typed messages:

type WSConn[I any] interface {
	BiDirStreamConn[I]
	ReadMessage(w *websocket.Conn) (I, error)
	OnStart(conn *websocket.Conn) error
}

### WSHandler[I any, S WSConn[I]] Validates HTTP requests and creates WebSocket connections:

type WSHandler[I any, S WSConn[I]] interface {
	Validate(w http.ResponseWriter, r *http.Request) (S, bool)
}

### BiDirStreamConn[I any] Provides lifecycle and message handling methods:

type BiDirStreamConn[I any] interface {
	SendPing() error
	Name() string
	ConnId() string
	HandleMessage(msg I) error
	OnError(err error) error
	OnClose()
	OnTimeout() bool
}

## Advanced Usage

### Multi-user Chat Server

type ChatServer struct {
	clients map[string]*ChatConn
	rooms   map[string]*Room
	mu      sync.RWMutex
}

type ChatConn struct {
	gohttp.JSONConn
	server   *ChatServer
	username string
	roomName string
}

func (c *ChatConn) OnStart(conn *websocket.Conn) error {
	if err := c.JSONConn.OnStart(conn); err != nil {
		return err
	}

	// Register with server
	c.server.mu.Lock()
	c.server.clients[c.ConnId()] = c
	c.server.mu.Unlock()

	return nil
}

func (c *ChatConn) HandleMessage(msg any) error {
	msgMap := msg.(map[string]any)

	switch msgMap["type"].(string) {
	case "chat":
		// Broadcast to all clients in room
		c.server.broadcastToRoom(c.roomName, msgMap)
	case "join_room":
		// Switch rooms
		c.joinRoom(msgMap["room"].(string))
	}

	return nil
}

### Authentication and Authorization

type SecureConn struct {
	gohttp.JSONConn
	userID string
	roles  []string
}

func (s *SecureConn) HandleMessage(msg any) error {
	msgMap := msg.(map[string]any)
	messageType := msgMap["type"].(string)

	if !s.hasPermission(messageType) {
		errorMsg := map[string]any{
			"type":  "error",
			"error": "Insufficient permissions",
		}
		s.Writer.Send(conc.Message[any]{Value: errorMsg})
		return nil
	}

	// Process authorized message
	return s.processMessage(msgMap)
}

type AuthHandler struct{}

func (h *AuthHandler) Validate(w http.ResponseWriter, r *http.Request) (*SecureConn, bool) {
	token := r.Header.Get("Authorization")

	// Validate JWT token
	claims, err := validateJWT(token)
	if err != nil {
		http.Error(w, "Invalid token", http.StatusUnauthorized)
		return nil, false
	}

	return &SecureConn{
		userID: claims["userID"].(string),
		roles:  claims["roles"].([]string),
	}, true
}

### Custom Ping-Pong with Latency Tracking

type MonitoredConn struct {
	gohttp.JSONConn
	lastPingTime time.Time
	pingCount    int64
}

func (m *MonitoredConn) SendPing() error {
	m.pingCount++
	m.lastPingTime = time.Now()

	pingMsg := map[string]any{
		"type":      "ping",
		"pingId":    m.pingCount,
		"timestamp": m.lastPingTime.Unix(),
	}

	m.Writer.Send(conc.Message[any]{Value: pingMsg})
	return nil
}

func (m *MonitoredConn) HandleMessage(msg any) error {
	msgMap := msg.(map[string]any)

	if msgMap["type"].(string) == "pong" {
		latency := time.Since(m.lastPingTime)
		log.Printf("Ping-pong latency: %v", latency)
	}

	return nil
}

## Configuration

### Production Configuration

config := &gohttp.WSConnConfig{
	BiDirStreamConfig: &gohttp.BiDirStreamConfig{
		PingPeriod: time.Second * 30,  // Send ping every 30 seconds
		PongPeriod: time.Second * 300, // Timeout after 5 minutes
	},
	Upgrader: websocket.Upgrader{
		ReadBufferSize:  4096,
		WriteBufferSize: 4096,
		CheckOrigin: func(r *http.Request) bool {
			// Implement proper origin checking
			return isValidOrigin(r.Header.Get("Origin"))
		},
	},
}

router.HandleFunc("/ws", gohttp.WSServe(handler, config))

### Development Configuration

config := gohttp.DefaultWSConnConfig()
config.PingPeriod = time.Second * 10  // Faster pings for development
config.PongPeriod = time.Second * 30  // Shorter timeout

## Frontend Integration

The framework is designed to work seamlessly with JavaScript WebSocket clients:

class WebSocketClient {
	constructor(url) {
		this.url = url;
		this.ws = null;
		this.pingInterval = null;
	}

	connect() {
		this.ws = new WebSocket(this.url);

		this.ws.onopen = () => {
			this.startPingInterval();
		};

		this.ws.onmessage = (event) => {
			const message = JSON.parse(event.data);
			this.handleMessage(message);
		};
	}

	handleMessage(message) {
		switch (message.type) {
			case 'ping':
				// Respond to server ping
				this.send({type: 'pong', pingId: message.pingId});
				break;
			default:
				this.onMessage(message);
		}
	}

	startPingInterval() {
		this.pingInterval = setInterval(() => {
			if (this.ws?.readyState === WebSocket.OPEN) {
				this.send({type: 'ping', timestamp: Date.now()});
			}
		}, 25000);
	}
}

## Error Handling and Resilience

The framework provides robust error handling:

type ResilientConn struct {
	gohttp.JSONConn
	errorCount int
	maxErrors  int
}

func (r *ResilientConn) OnError(err error) error {
	r.errorCount++
	log.Printf("WebSocket error #%d: %v", r.errorCount, err)

	if r.errorCount > r.maxErrors {
		return err // Close connection after too many errors
	}

	return nil // Continue with connection
}

func (r *ResilientConn) OnTimeout() bool {
	log.Printf("Connection timeout for %s", r.ConnId())
	return true // Close the connection
}

## Best Practices

• Always call parent OnStart/OnClose when embedding JSONConn
• Implement proper authentication in the Validate method
• Use connection limits to prevent resource exhaustion
• Handle errors gracefully without crashing the server
• Clean up resources properly in OnClose methods
• Use mutexes for thread-safe operations on shared state
• Monitor connection health with metrics

## Common Patterns

### Hub Pattern for Broadcasting

type Hub struct {
	clients    map[*Client]bool
	broadcast  chan []byte
	register   chan *Client
	unregister chan *Client
}

func (h *Hub) run() {
	for {
		select {
		case client := <-h.register:
			h.clients[client] = true
		case client := <-h.unregister:
			delete(h.clients, client)
		case message := <-h.broadcast:
			for client := range h.clients {
				client.send <- message
			}
		}
	}
}

### Room-based Messaging

type Room struct {
	name    string
	clients map[string]*Client
	mu      sync.RWMutex
}

func (r *Room) Broadcast(message any, excludeId string) {
	r.mu.RLock()
	defer r.mu.RUnlock()

	for id, client := range r.clients {
		if id != excludeId {
			client.Send(message)
		}
	}
}

## Testing

The package includes comprehensive test utilities for WebSocket testing:

// Create test server
server := httptest.NewServer(router)
defer server.Close()

// Create WebSocket client
wsURL := "ws" + strings.TrimPrefix(server.URL, "http") + "/endpoint"
conn, err := createTestClient(t, wsURL, nil)
if err != nil {
	t.Fatalf("Failed to connect: %v", err)
}
defer conn.Close()

See the comprehensive test suite in ws2_test.go for complete examples of testing WebSocket applications including authentication, load testing, and error scenarios.

HTTP Utilities ¶

The package also provides utilities for HTTP request/response handling:

• JsonToQueryString: Convert maps to URL query strings
• SendJsonResponse: Send JSON responses with proper error handling
• ErrorToHttpCode: Convert Go errors to appropriate HTTP status codes
• WSConnWriteMessage/WSConnWriteError: WebSocket message writing utilities
• NormalizeWsUrl: Convert HTTP URLs to WebSocket URLs

Example HTTP utility usage:

func handleAPI(w http.ResponseWriter, r *http.Request) {
	data, err := processRequest(r)
	gohttp.SendJsonResponse(w, data, err)
}

This comprehensive framework enables building production-ready real-time applications with WebSocket communication, from simple echo servers to complex multi-user systems with authentication, rooms, and advanced connection management.

// Create router and server
router := mux.NewRouter()

// Chat server setup
chatServer := &ChatServer{
	clients: make(map[string]*ChatConn),
	rooms:   make(map[string]*Room),
}

// Add handlers
router.HandleFunc("/echo", WSServe(&EchoHandler{}, nil))
router.HandleFunc("/chat", WSServe(&ChatHandler{server: chatServer}, nil))
router.HandleFunc("/secure", WSServe(&AuthHandler{}, nil))

// Custom configuration for production
config := &WSConnConfig{
	BiDirStreamConfig: &BiDirStreamConfig{
		PingPeriod: time.Second * 30,
		PongPeriod: time.Second * 300,
	},
	Upgrader: websocket.Upgrader{
		ReadBufferSize:  4096,
		WriteBufferSize: 4096,
		CheckOrigin: func(r *http.Request) bool {
			// Add proper origin checking in production
			return true
		},
	},
}

router.HandleFunc("/production", WSServe(&EchoHandler{}, config))

// In a real application, you would start the server:
// log.Fatal(http.ListenAndServe(":8080", router))

fmt.Println("WebSocket server configured with multiple endpoints:")
fmt.Println("- /echo: Simple echo server")
fmt.Println("- /chat: Multi-user chat with rooms")
fmt.Println("- /secure: Authenticated connections")
fmt.Println("- /production: Production-ready config")

Output:
WebSocket server configured with multiple endpoints:
- /echo: Simple echo server
- /chat: Multi-user chat with rooms
- /secure: Authenticated connections
- /production: Production-ready config