I was planning to use "Trusted Authentication" to share an embedded chart with lots of users (not all of whom have licenses). Some of those users will only look at the chart maybe once a year, and we can't justify buying them an entire license to look at a chart once.
This page says "everyone who visits the page must be a licensed user on Tableau Server": http://onlinehelp.tableausoftware.com/v7.0/server/en-us/trusted_auth.htm
If you want more details on how to implement Trusted Authentication using PHP, first visit the following folder on your server: C:\Program Files\Tableau\Tableau Server\8.1\extras\embedding\php
It has some sample code, but you need to install version 1.x of pecl_http to make it work. The guides for that are:
- http://www.mkfoster.com/2009/01/04/how-to-use-the-pecl-http-pecl_http-extension-to-make-http-requests-from-php/ (careful, this guide will install pecl_http 2.x which is too different to work)