Ask two PHP applications and a Java application how to implement single sign-on

How do two PHP applications and one Java application implement single Sign-on?
Ask two PHP applications and one Java application, each application database is isolated from each other, but in the same domain:
such as app1.domain.com, app2.domain.com and app3.domain.com
PHP is based on APAHCE + PHP 5.2 development, and Java applications are based on GlassFish 3.1.2 development.

Is there any way to do single sign-on?

------Solution--------------------
Java
Cookie MyCookie = new cookie ...
Mycookie.setdomain (". domain.com");
......


Php

Setcookie ("Key", $value, $time, "/", ". domain.com");





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Passing the login information via JS is not related to the domain
------Solution--------------------
Make a common authentication system.
When a user logs in to an application, it is passed to the user a unique token flag, and when the user accesses another application, the token is taken, and the authentication system will assume that the user is logged in.
Specific implementations can refer to many of the company's SSO systems.

Web applications, the simplest is actually the way cookies are.

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