PHP chat application: Accumulation+Concatenation working, but only on individual hosts? - php

Question

I have a textarea in which you type your message and a textarea that is supposed to output all messages from any hosts on my page:
<form action= "chatroom.php" method="post">
Chatbox:<textarea name="results" rows="10" cols="40">
<?php
$accum = $results . $message;
echo $accum;
?>
</textarea>
<br>
Send message:<textarea name="message" rows="7" cols="30"></textarea>
<input type="submit" value="Send" name="send">
</form>
It works fine, but only on any individual computer.
I don't believe it's a server issue (using WAMP). The site is on the web, and other echoes do appear on other clients such as
echo "<br>Connected to MySQL.<br>";
But, when I send a message on my server computer, it does not appear in the Chatbox textarea on my host computer, or vice versa.
Already tried moving the Chatbox textarea outside the form, which did not solve the problem.
Tried just echoing $accum straight onto the page and not into the textarea, which did not fix the problem.
<?php session_start(); ?>
at the start of chatroom.php didn't work either.
As a side note I'm using mySQL and used "localhost" rather than my external IP in mysqli, in my php code. I don't think this is the problem because the database does add a new user when they sign up remotely.
I thought that all PHP was executed on the server, so shouldn't $accum be picking up text from all hosts?
I'm wondering if the problem is that all clients have their own $message, $results and $accum variable because each client is connected to the server, and not to each other? So would that explain the behavior? (Or am I not completely correct?)
And forgot to mention, I am refreshing the page via clicking Send again to check if the text appeared; I haven't implemented auto-refresh yet.
edit:
in chatroom.php:
<?php
$message = $_POST["message"];
$results= $_POST["results"];
?>
I'm just turning the html name parameter into a php variable, then posting that variable right back onto the page in a different location.
Also have:
<?php
$username = $_POST["username"];
$word = $_POST["word"];
$conn = new mysqli("localhost", "user", "pw", "", 8080);
if($conn->connect_error)
echo $conn->connect_error;
else
echo "<br>Connected to MySQL.<br>";
if ($conn->query("create database chatdb")===TRUE)
echo "Created database";
else
echo $conn->error;
if ($conn->query("use chatdb")===TRUE)
echo "using chatdb";
else
echo "<br>Not using chatdb<br>";
if (
$conn->query("create table
users(
id INT(6) unsigned auto_increment primary key,
username varchar(30),
word varchar(30)
)")===TRUE)
{
echo "table created";
}
else
echo $conn->error;
if ($conn->query("insert into users (username, word) values ('$username',
'$word')")===TRUE)
echo "<br>inserted values<br>";
else
echo $conn->error;
?>
My sign-up page:
Sign Up:
<form action="chatroom.php" method="post">
Username:<input type="text" name="username"><br>
Password:<input type="text" name="word"><br>
<input type="submit" value="Sign Up!" name="signup">
</form>
Again, I don't think the mySQL has anything to do with it-- but I could be wrong.

Answer 1

The HTTP protocol is a Request/Response protocol. When someone displays the chat page, I assume your code reads messages from the database and shows those.
There was a request (GET /chat.php, Response is HTML for chatpage) and at that point the connection between the web browser and server is closed.
After that, there is no way for that web client to know that someone posted a new message into the database unless:
There is a persistent socket connection (websockets) OR
Your application is polling the server (perhaps using a timer and ajax calls OR
Your client application is refreshing at some interval
Solutions 1,2 and 3 require some level of javascript competency.