in reply to CGI and persistent data
I'd like to be able to 'carry' the data structure without having to 'store' it to disk, if possible
well, you'll have to store the data structures somewhere. Your choices will probably be in a cookie, as a hidden param or as part of your session, And session info will typically either use a flat file or a db. As porta pointed out, you could just use CGI::Session or CGI::Application::Plugin::Session to do the latter. That would be my recommendation too, as it has a nice API for saving and retrieving the data.