Question

I was wondering if there is a global session concept in tomcat (à la PHP). Imagine a really vanilla webapp with a servlet that takes input via POST and dumps them into an object (ignore obvious security concerns). The index page then just displays all the input so far.

I would like to put this object into a global variable. I can go the static methods / singleton route but just wondering if tomcat supports global variables.

Thanks!

Answer 1

There is many context in the Servlet specifications:

1. Servlet or application context. This let you store object that can be shared across of all the application a for all the clients (browsers). The objects stored in this context are alive until the application is undeployed or the container (Tomcat) is shutted down
2. Session context. This let you store objects in the session of the client (browser session). Also this objects are alive until the session of the users expires
3. Request context. This let to you store objects across the different requests. The objest stored in the requests are alive until the request is completed

I hope this can help you.