Question: My server provides SSL connections via https, although the certificate costs extra...

Is there anything that needs to be changed in the PHP code to utilize this protocol?

My site has:

* ajax forms via POST
* regular forms and pages using POST and GET parameters
* Session variables

Answer: 
you can use the server .htaccess file to redirect all your links. So when the standard page is opened via say a link the server redirects to the https version...

```
# Permanent reirect ALL old pages to HTTPS:
RewriteCond %{HTTPS} off
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

```
The code does not need to be changed, other than to change all links from `http://` to `https://` (seriously, don't forget that, else you aren't using SSL...)