I have seen several developers looking for a solution for this problem: accessing session information from a different WAR (even when inside the same EAR) - here are some samples: Any way to share session state between different applications in tomcat?, Access session of another web application, different WAR files, shared resources, Tomcat: How to share data between two applications?, What does the crossContext attribute do in Tomcat? Does it enable session sharing? and so on...
From all I have searched, there are some specific solutions depending on the container, but it is somehow 'contrary to the specification'. I have also looked through Java EE specification without any luck on finding an answer.
Some developers talk about coupling between web applications, but I tend to disagree. What is the reason one would keep WARs inside the same EAR if not coupling? EJBs, for instance, can be accessed locally (even if inside another EJB JAR within the same EAR).
More specifically, one of my WARs handles authentication and authorization, and I would like to share this information with other WARs (in the same EAR). I have managed to work around similar problems before by packaging WARs as JARs and putting them into a singular WAR project (WEB-INF/lib). Yet I do not like this solution (it requires a huge effort on servlet naming and so on).
And no solution has answered the first (and most important) question: Why can't WARs share session information?