Multiple Sessions Running Consecutively with PHP

While implementing a inventory control system using PHP, I realized that I needed a way to allow my users to run multiple copies of the same program at the same time. To accomplish this, I needed a unique identifier for each session.

Each session can be assigned a unique session name using the "session_name" function. There are two steps to creating a unique session name.

1. If the variable "$mysession" does not exist, create a session name using the program name and timestamp. I originally used "mktime", but changed to "microtime" to avoid duplicate timestamps.

//Start a PHP session to preserve variables.
        if ( empty($mysession) ) {
            $micro  = microtime();
            $micro = str_replace(" ","",$micro);    // strip out the blanks
            $micro = str_replace(".","",$micro);    // strip out the periods
            $mysession = "po_maint" . $micro;
        }
        session_name($mysession);
        session_start();

2. The variable "$mysession" must be passed from page to page. It cannot be a session variable because this variable is being used before the session is activated. It cannot be a cookie because mutiple programs would try to overwrite the "mysession" cookie. It can be passed as a hidden field in each form or appended to the URL.