title: Shibboleth with custom web application's own SignOn mechanism
body: <p>We are developing a web application that has its own SignOn mechanism (login mechanism using username and password). The SignOn mechanism is implemented using a Web Application Filter)</p>
  
  <p>The web application container is Apache Tomcat 6.0</p>
  
  <p>The User may also choose to login through Shibboleth authentication. That is, to access our Web Application, the user may choose either be authenticated using Shibboleth, or using our own SignOn mechanism which is web application filter-based.</p>
  
  <p>Is it technically feasible to support both Shibboleth Authentication, and a Web Application Filter based SignOn mechanism?</p>
  
  <p>If it's feasible, from the Web Application Filter side, how do we check if a user was authenticated already by Shibboleth? Is there some Shibboleth Authentication token, or Shibboleth User session?</p>
  
  <p>Thanks.</p>