Step 1 would be for you to design this or write your software design document. Many new programmers forget to sketch out what they want and proceed to code first. https://en.wikipedia.org/wiki/JavaServer_Pages is an interesting read and if I was to tackle this my bet is it's more than one chunk of code but a design.
For example since the diagram there indicates you have a browser on the client, that would be in your spec as well.
That is, who said the notification was via web browser, email, text message or a phone call?