title: Single Sign On [SSO] across different domains using Java
body: <p>We are implementing Single Sign On [SSO] across multiple applications, which are hosted on different domains and different servers.</p>
  
  <p><img src="https://i.stack.imgur.com/mB63q.png" alt="enter image description here"></p>
  
  <p>Now as shown in the picture, We are introducing a Authenticate Server which actually interacts with LDAP and authenticate the users. The applications, which will be used/talk to Authenticate Server are hosted across different Servers and domains.</p>
  
  <p>for SSO, I can't use session variables, as there are different servers and different applications, different domains, a domain level cookie/session variable is not helpful.</p>
  
  <p>I am looking a better solution which can be used for SSO across them. Any demonstrated implementation is existing? If so, please post it or point me in the right direction for this.</p>