example_connection_extension.go

package main

import (
	"flag"
	"fmt"
	"github.com/trevex/golem"
	"log"
	"net/http"
)

var addr = flag.String("addr", ":8080", "http service address")

// This struct represents the message which is accepted by
// the hello-function.
// If a handler function takes a special data
// type that is not an byte array, golem automatically
// tries to unmarshal the data into the specific type.
type Hello struct {
	To   string `json:"to"`
	From string `json:"from"`
}

// Type of data being emitted with answer-Event
type Answer struct {
	Msg string `json:"msg"`
}

// Extended connection type embedding the simple connection to provide the same functionality.
type ExtendedConnection struct {
	*golem.Connection
	Counter int
}

// An additional method for the extended type
func (e *ExtendedConnection) answer(msg string) {
	e.Emit("answer", &Answer{msg})
}

// Constructor of the extended connection
func NewExtendedConnection(conn *golem.Connection) *ExtendedConnection {
	return &ExtendedConnection{
		Connection: conn,
		Counter:    1, // to illustrate the persistence of the extension
	}
}

// Function taken special data type and utilizing golem's
// inbuilt unmarshalling
func hello(conn *ExtendedConnection, data *Hello) {
	conn.Counter += 1
	fmt.Println("Hello from", data.From, "to", data.To, "Counter:", conn.Counter)
	conn.answer("Thanks, client!")
}

// Event but no data transmission
func poke(conn *ExtendedConnection) {
	conn.Counter += 1
	fmt.Println("Poke-Event triggered! Counter:", conn.Counter)
	conn.answer("Ouch I am sensible!")
}

func main() {
	flag.Parse()

	// Create a router
	myrouter := golem.NewRouter()
	// Enable the extension
	myrouter.SetConnectionExtension(NewExtendedConnection)
	// Add the events to the router
	myrouter.On("hello", hello)
	myrouter.On("poke", poke)

	// Close callback
	myrouter.OnClose(func(conn *ExtendedConnection) {
		fmt.Println("Connection closed with counter at:", conn.Counter)
	})
    // Connect callback
    myrouter.OnConnect(func(conn *ExtendedConnection) {
        fmt.Println("User connected counter at:", conn.Counter)
    })

	// Serve the public files
	http.Handle("/", http.FileServer(http.Dir("./public")))
	// Handle websockets using golems handler
	http.HandleFunc("/ws", myrouter.Handler())

	// Listen
	if err := http.ListenAndServe(*addr, nil); err != nil {
		log.Fatal("ListenAndServe:", err)
	}
}