How to Use apache_note() for Inter‑Module Communication in Apache

The apache_note() function is a PHP wrapper around Apache's table_get and table_set mechanisms, allowing modules to read and write entries in the request's internal notes table.

It accepts two arguments: note_name , a string identifying the note, and an optional note_value , the string value to store. If only note_name is supplied, the function returns the current value of that note.

When both arguments are provided, the function sets the note to note_value and returns the previous value. If the note cannot be accessed, the function returns FALSE.

Typical usage involves one module writing a value that another module later reads within the same request, enabling lightweight inter‑module communication.

<?php
apache_note('name', 'Fredrik Ekengren'); // set a note
// Call perl script
virtual('/perl/some_script.pl');
$result = apache_note('resultdata'); // retrieve a note
?>

The example demonstrates setting a note called name, invoking a Perl script via virtual(), and then reading a note named resultdata.