title: Questions about openid and dotnetauthentication
body: <p>I am looking into openid and dotnetauthentication library. However I still go some outstanding questions.</p>
  
  <ol>
  <li><p>the id that comes back is that unique for each user? Can I store this id in a database as the userId(currently this field is a primary key and unique identifier)</p></li>
  <li><p>I read that you can try to request information such as email address but you may not give it to you. What happens if you need this information? </p></li>
  </ol>
  
  <p>I think it kinda sucks if I have to popup another field right away and ask for their email address and whatever else fields I need. Sort of seems to defeat the purpose a bit as I always considered a benefit of openid is that you don't have to fill out registration forms. </p>
  
  <ol>
  <li>Is it better to only have some predefined choices(google,yahoo,openid,facebook). Then letting them type in their own ones(ie gray out the field to let them type in a url).</li>
  </ol>
  
  <p>I am thinking of this because it goes back to point number 2 if they type in a provider that does not give me the information that I need I am then stuck.</p>
  
  <ol>
  <li>How do you a log person out? Do you just kill the form authentication ticket?</li>
  </ol>