Handler modules : Content Handler vs Content Phase Handler (1 reply)

Hello !
I'm developping some handler modules for nginx and I'm wondering why they are two kinds of handlers :
- Content Phase Handler
- Content Handler

I read this interesting blog : http://www.nginxguts.com/2011/01/phases/
As far as I understood, the content handler could only be called once in a location configuration and the content phase handler is called everytime.
Is there a reason to prefer one type instead of another?

My last question is if there is a solution to develop content phase handler modules without calling them each time, but only if they are activated in the nginx.conf file?

Thanks in advance for helping me to understand this !