red5 and openfire relations

Hi,

I understand that red5 and openfire operates in parallel.

Two users can perform an XMPP IM session through openfire and in the same time

publish and recive video and audio streams from each other using red5.

I'm trying to understand how the integration is actually working.

Are the XMPP application and the A/V application can be considered completely separated?

Is the initial handshaking between the two users before the A/V is performed using XMPP?

What is the advantage of using both openfire and red5 over using only red5 with shared objects for the chat?

Thanks