使用PHP，websockets和MySQL聊天

Question

I'm trying to write a chat using this https://github.com/ghedipunk/PHP-Websockets PHP class. Now it looks like, on beginning JS on client side connect to server, then it sends a request once a 3 seconds, and server on every request check messages in database, and send messages to client. I think it's not good, that client sends request once a 3 sec, and I wonder how to do, that server send message to client, only when there is a new message in database? This is my extended process function:

protected function process($user, $message) {
    $databaseHandler = mysqli_connect('blahblah');  
    $decoded = json_decode($message, true);
    $chat_id = $decoded['chatid'];
    $limit = $decoded['limit'];
    $user_id = filterString($decoded['userid'], $databaseHandler);
    $SQLQuery = "SELECT chat_messages.message, users.name FROM chat_messages JOIN users ON chat_messages.user_id=users.user_id WHERE chat_messages.chat_id = '$chat_id' ORDER BY chat_messages.message_id DESC LIMIT $limit,5;";
    $SQLResult = mysqli_query($databaseHandler, $SQLQuery);
    $i = 0;
    $arr = array();
    while ($row = mysqli_fetch_assoc($SQLResult)) {
        $i++;
        $arr[$i] = $row['name'] . ': ' . $row['message'];
    }


    $this->send($user, json_encode($arr));

}

This is JS function:

function refreshchat() {

try {
    socket.send('{"token":"' + token + '","userid":'+ userid +'"chatid":' + chatid + ',"limit":' + limit + '}');

} catch (ex) {
    console.log(ex);
}
setTimeout(refreshchat, 3000);

}

I skipped authorization stuff in php for clearance.

Thank you in advance!

Answer 1

Well you are using setTimeout JavaScript function. It only runs once. You can use setInterval function. It is run repeatedly. ( http://www.w3schools.com/jsref/met_win_setinterval.asp )

It seems you want a feature that allows the server to inform the client that there is a new chat message. I think using timer in Javascript is a good option. You can also check the push notification api: https://developers.google.com/web/updates/2015/03/push-notifications-on-the-open-web .