Given that approach, my question is how to show intercepting filter in sequence diagram. For example, if user finishes shopping and checks out, an intercepting filter can check if user is signed on and if not, direct user to sign on first.
With FacesServlet in place, I think the sequence diagram goes something like below:
Some JSF page ----> FacesServlet ---> PhaseListener (as intercepting filter) -----> Signon JSF page--> back to PhaseListener --> back to FaceServlet ----> show Cart JSF page and allow user to check out
How do you show the intercepting filter pattern in sequence diagram without FaceServlet and PhaseListener in place?