title: Multi service with one-login authentication (Single sign-on)
body: <blockquote>
    <p>Single sign-on (SSO) is a property of access control of multiple related, but independent software systems. With this property a user logs in once and gains access to all systems without being prompted to log in again at each of them. (from <a href="https://en.wikipedia.org/wiki/Single_sign-on" rel="nofollow">wikipedia</a>)</p>
  </blockquote>
  
  <p>now, I have more web service:</p>
  
  <ul>
  <li>www.a.com </li>
  <li>www.b.net </li>
  <li>www.c.org</li>
  <li>www.n.it</li>
  </ul>
  
  <p>with more login page (and logout, register account, recover password... page), eg:</p>
  
  <ul>
  <li>www.a.com/login.php</li>
  <li>www.b.net/login.asp</li>
  <li>www.c.org/login</li>
  <li>www.n.it/login</li>
  </ul>
  
  <p>all these pages authenticate users from the same database.</p>
  
  <p>I have a dream, one authentication service, eg:</p>
  
  <ul>
  <li>www.a.com/login.php --> redirect to --> auth.acme.com/login</li>
  <li>www.b.net/login.asp --> redirect to --> auth.acme.com/login</li>
  <li>www.c.org/login --> redirect to --> auth.acme.com/login</li>
  <li>www.n.it/login --> redirect to --> auth.acme.com/login</li>
  </ul>
  
  <p>I'm trying different solutions, eg. <a href="https://en.wikipedia.org/wiki/Security_Assertion_Markup_Language" rel="nofollow">SAML</a> protocol with <a href="https://simplesamlphp.org/" rel="nofollow">SimpleSAMLphp</a>, but for me <em>SAML is like building a nuclear reactor to power a light bulb.
  it seems that I am over engineered something that should be very simple: Single Sign-On</em> (quote <a href="https://systoilet.wordpress.com/2010/09/29/i-hate-saml/" rel="nofollow">I Hate SAML!</a>).</p>
  
  <p><strong>The question</strong></p>
  
  <p>I would an "Single Sign-On" architecture, starting from something (eg. framework, stack) as simple. There something like "SAML for dummies?"</p>