title: Expiration date of accessToken in oAuth protocol
body: <p>I'm using <code>dotNetOpenAuth</code> to authorise against Google <code>oAuth</code> provider.</p>
  
  <p>I'm a bit confused with the difference between the following:</p>
  
  <p><code>consumerToken</code>, <code>consumerSecret</code>, <code>accessToken</code></p>
  
  <p>From the Provider I get the <code>accessToken</code> for some user. Can keep I it forever? Or does it expires?</p>
  
  <p>How can the code enable authorization without redirecting the user to the "allow access to my google data page" ?</p>