I did all what had to be done ... create db, put resource in conf/context.xml and it doesnot work ....
When I run on server, it keeps saying http-status 404 mappings ....

What do I have to do, did I forgot something?

Well, let's try it again.
I used Tomcat 8.0.30 and installed the latest version 8.0.32. In persistence.xml I filled in all the necessary things for the Connection, instead of putting it in the context.xml from tomcat.
Also in the persistence.xml, I filled in the Managed classes used, Author, Book and Publisher. I run it and it worked, one day later I tried it again and it did not work again until now.

I tried to clean Tomcat, clean workdirectory, delete and install tomcat server again, but still it doesn't work .....

I want to update my post ....

Given:

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>
<%@ taglib prefix="spring" uri="http://www.springframework.org/tags" %>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>

I changed it to (Just remove the last two spring taglibs, because they are redundant).

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>


I also added the following to pom.xml.

<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.6</version>
</dependency>

This is so the application can connect to the database.