title: Implement CAS Single Sign Out for Cross Domain Applications
body: <p>I am a beginner in using CAS. My CAS server is up and running at port 8443(Secured HTTP layer). I have also made two applications - JAVA Client(My own JAVA Client) and PHP Client(Officially provided by CAS) for testing my CAS server. I am able to use single Sign On for both of the clients. I have also enabled Single Sign Out in the CAS properties file. My current version of CAS is <strong>4.0.0</strong> and I am using Apache Tomcat version <strong>8.0.23</strong></p>
  <p>I have added the following dependency for Sign Out in web.xml for <strong>JAVA Client</strong></p>
  <pre><code> &lt;filter&gt;
      &lt;filter-name&gt;CAS Single Sign Out Filter&lt;/filter-name&gt;
          &lt;filter-class&gt;  org.jasig.cas.client.session.SingleSignOutFilter&lt;/filter-class&gt;
  &lt;/filter&gt;
  &lt;filter-mapping&gt;
     &lt;filter-name&gt;CAS Single Sign Out Filter&lt;/filter-name&gt;
      &lt;url-pattern&gt;/*&lt;/url-pattern&gt;
  &lt;/filter-mapping&gt;
  &lt;listener&gt;
  &lt;listener-class&gt;  org.jasig.cas.client.session.SingleSignOutHttpSessionListener&lt;/listener-class&gt;
  &lt;/listener&gt;
  </code></pre>
  <p>But while performing Single Sign Out, When I log out of PHP Application I am unable to log out of already opened JAVA Applications. This means that on logging out from PHP application does not destroy my existing JAVA Application Sessions.</p>
  <p>So after a lot of research I came across <a href="https://stackoverflow.com/questions/44509/single-sign-on-across-multiple-domains">this</a> and I was successfully able to implement Sign Out feature. But I do not want to use a common session database.</p>
  <p>In the official <a href="http://jasig.github.io/cas/development/installation/Logout-Single-Signout.html" rel="nofollow noreferrer">documentation of CAS</a> it is mentioned that:</p>
  <blockquote>
  <p>CAS sends an <strong>HTTP POST</strong> message directly to the service ( back channel communication): this is the traditional way of performing notification to the service.</p>
  <p>When CAS is configured for SLO, it attempts to send logout messages to every application that requested authentication to CAS during the SSO session.</p>
  </blockquote>
  <p>But I am unable to understand how to fetch the <strong>SLO</strong> message as I do not receive any POST request( while tracking using firebug) during logout of an application. So Can anyone please help me to perform Single Sign Out.</p>
  <p>Thanks in advance.</p>