A method call inside your servlet has thrown an IOException resulting from a lost network connection to a necessary resource. The servlet has determined that it will
be unable to operate successfully fen few minutes, but expects to be able to resume operation after that period. How should this situation handled?
The servlet should re-throw the exception to the web container.
The servlet should throw a servletException to the web container.
The servlet should throw an unavailableException to the web container.
The servlet should redirect to an error page that reports the exception message.
The servlet should retry the request until the method returns successfully.
http://jcp.org/aboutJava/communityprocess/first/jsr053/servlet23_PFD.pdf (page 26, topic: 18.104.22.168, first paragraph)