How to separate "view" and "control" layers easily without RMI, messaging etc.?

I have applications built on Spring 3 + JPA 2 + JSF 2/Vaadin running on servlet container (Tomcat/Jetty).

My app is now a monilitic web application. It does three things:

• provides web user interface开发者_StackOverflow via JSF 2 or Vaadin
• provides RESTful services for external users
• does some very important processing in scheduled jobs

What I need is to easily redeploy changes in interface without stopping REST services and scheduled jobs. I know I can create two (or more) web apps and use RMI intrefaces or message queue for remote method invocation. I'm looking for something simpler. Those applications may run on single Tomcat (single JVM).

People say: "In PHP I can change button/table/panel... without stopping anything". I'd like to keep simple things simple.

How do You solve this kind of problems? Is OSGi the only solution? I think OSGi is way too complicated for such simple scenario.

OSGi is not complicated! I would recommend having a look at Virgo. It supports deploying pure web applications to start with. From there you can gradually break up the web app into bundles and ending with a "pure" bundle only application where modules can easily be upgraded on the fly.