ottodidakt ottodidakt - 6 months ago 23
Java Question

Abort java webapp on startup

My webapp is part of a larger EAR that is deployed into a websphere server. The server hosts number of other apps on the same virtual server. My webapp has some initialisation/health checks in a servletContextListener->contextInitialized method. I want to make the webapp unavailable if initialisation/health checks fail. What is a realiable way of doing this? Will throwing a RuntimeException from within contextInitialized suffice? Is the rest of the EAR still expected to be available? Thank you.

Answer

I'd recommend throwing a RuntimeException from ServletContextListener.contextInitialized.

Servlet 2.3 wasn't very clear on this, but Servlet 2.4 added the following detail, carried into Servlet 3.1 Section 11.6:

Some exceptions do not occur under the call stack of another component in the application. An example of this is a … ServletContextListener that throws an unhandled exception during a notification of servlet context initialization…. In this case, the Developer has no opportunity to handle the exception. The container may respond to all subsequent requests to the Web application with an HTTP status code 500 to indicate an application error.

Since it says that the servlet engine "may" disable access to application, you might find a server that does something else. However, Tomcat and WebLogic both disable the application, and the only other reasonable thing I can think of would be to ignore the exception. I can't see a container that did that being very popular—so you'd better test it in WebSphere yourself.