It is expected that many websocket clients and servers will exchange data in JSON format. For Go programs this means that a Go object will be marshalled into JSON format as described in Chapter 4: Serialisation and then sent as a UTF-8 string, while the receiver will read this string and unmarshal it back into a Go object.
The websocket convenience object JSON will do this for you. It has methods Send and Receive for sending and receiving data, just like the Message object.
A client that sends a Person object in JSON format is
/* PersonClientJSON
*/
package main
import (
"code.google.com/p/go.net/websocket"
"fmt"
"os"
)
type Person struct {
Name string
Emails []string
}
func main() {
if len(os.Args) != 2 {
fmt.Println("Usage: ", os.Args[0], "ws://host:port")
os.Exit(1)
}
service := os.Args[1]
conn, err := websocket.Dial(service, "",
"http://localhost")
checkError(err)
person := Person{Name: "Jan",
Emails: []string{"[email protected]", "[email protected]"},
}
err = websocket.JSON.Send(conn, person)
if err != nil {
fmt.Println("Couldn't send msg " + err.Error())
}
os.Exit(0)
}
func checkError(err error) {
if err != nil {
fmt.Println("Fatal error ", err.Error())
os.Exit(1)
}
}and a server that reads it is
/* PersonServerJSON
*/
package main
import (
"code.google.com/p/go.net/websocket"
"fmt"
"net/http"
"os"
)
type Person struct {
Name string
Emails []string
}
func ReceivePerson(ws *websocket.Conn) {
var person Person
err := websocket.JSON.Receive(ws, &person)
if err != nil {
fmt.Println("Can't receive")
} else {
fmt.Println("Name: " + person.Name)
for _, e := range person.Emails {
fmt.Println("An email: " + e)
}
}
}
func main() {
http.Handle("/", websocket.Handler(ReceivePerson))
err := http.ListenAndServe(":12345", nil)
checkError(err)
}
func checkError(err error) {
if err != nil {
fmt.Println("Fatal error ", err.Error())
os.Exit(1)
}
}