Hi,

I'm trying to get my head around making a processing applet that communicates with MySQL. Processing cannot communicate directly with an MySQL server because the applet is running on the clients machine, which is not a 'trusted host' for communicating with the MySQL server, correct???

So in order to have my Applet talk to MySQL, I should send all my queries to some PHP and have that talk to the database, and spit it back to processing???

I've also heard a bit about 'servlets' in the forums. Is that another way to do it?

I am new to MySQL and processing, and have a bit of experience with PHP. MUCH help is appreciated.

hi

it's really quite easy to use a PHP script to communicate between MySQL and p5.  no need to sign the applet or talk to tomcat unless you're sending too much data for a GET request (the maximum length of a URL for the server, which i think is by default about 2000 characters on iis/windows servers and about 8000 on apache/*nix servers).

i believe it's actually more secure to handle the databse stuff in a php script than in p5 because a java applet can potentially be decompiled and then your MySQL login/password/server is available to be borrowed/stolen/h4xx0red.

to talk to mysql through php, i just use loadStrings(url) where the String url has been composed of data i want to insert into the database.

for example:
Code:

String url = "http://domain.com/insert.php?color=" + theColor + "&size=" + theSize;
loadStrings(url);
 

that loadStrings() is just to get p5 to send the request; the script doesn't actually return any text to it.

the insert.php file will look something like this:
Code:

 // insert.php
<?PHP
$dblink = mysql_connect("mysqldatabase.domain.com", "mysql_username", "mysql_password");
mysql_select_db("name_of_database");

$color = $_GET['color];
$size = $_GET['size'];

$sql = "INSERT INTO squares SET size='$size' color='$color'";
$result = mysql_query($sql);
?>
 

then to read out all squares from the database, i'll have a script called 'read.php' or something that looks like this:
Code:

 // read.php
<?PHP
$dblink = mysql_connect("mysqldatabase.domain.com", "mysql_username", "mysql_password");
mysql_select_db("name_of_database");

$sql = "SELECT * FROM squares";
$result = mysql_query($sql);

while($row = mysql_fetch_array($result)) {
    echo $row['color'];
    echo " || ";
    echo $row['size'];
    echo "\n";
}
?>
 

the output is easy to parse with p5's split().

keeping the database access logic on the server has the additional advantage that if you need to change your database structure or something you can do so without requiring users to download a new client.

hope this is helpful!
-jake

You can use loadStrings and give it a URL with parameters to send, e.g.
Code:

String result=loadStrings("http://www.myhost.com/foo/wibble.php?foo=bar&ping=quux");
 

And your wibble.php can talk to MySQL do whatever it needs, and return the result to processing as a String[] to handle however you like.

I'm having the same problem. I don't want anything more to happen than this Code:

lines = loadStrings("data_grabber.php"); 

but there's a delay I think that's messing it up...

Here's where I posted roughly the same problem earlier today. If I find the answer, I'll let you know.

Evidently my problem was a lot harder to solve because an old applet is stuck in my firefox cache.. even after using the java control panel to flush out its temp files, it sticks. Once I got your code working with the run button (flakey.. but magically worked finally when i'm sure i changed nothing) it worked in IE. I appreciate the help. Thanks!