Oracle APEX - How to tell if your instance is running EPG, Apex Listener or HTTP

I recently stood up an Amazon AWS instance with Oracle 11 and Apex installed to test it out (more on this later). I found that the version of Apex installed on this instance is Apex 3.2, and I'm already working on Apex 4.1. In the process of upgrading the Apex version I need to determine what web server type the existing installation is using. It could be the Embedded PL/SQL Gateway EPG, Apex Listener or HTTP.

Here's how to check what web server you're using. Note that this works from the Oracle APEX SQL Workshop by errors out on my installation from sqlplus or OEM with a numeric PL/SQL error.

Just go into SQL Worksop -> SQL Commands and enter and execute this:

select owa_util.get_cgi_env('SERVER_SOFTWARE') from dual

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