addition of session happens on new req out, resp out for new req, But this is called whenever any message is being sent out. If both the local and remote tags are present then add in the full_dialogs hash, otherwise just add in the half_dialogs hash, in both cases mark in the session if the session was in half dialog hash and you are adding in full then remove from HD Map. If the session is already in full then do not do anything.

Invoked on all incoming responses with or w/out remote tag and incoming requests with or without both tags. For requests without to tag a new session is created and when responded to, it transitions to full_dialogs from half dialogs