Last week, I wrote about the creative use one can make of Filters by grading assignments of students. About, there’s another recurring issue that warrants a blog post: servlet mappings. While servlet mappings seem easy on the surface, they sometimes can be the cause of huge headaches. The issue In the assignment mentioned above, students have to create a mock e-commerce shop application. The home page shows a title, an introduction phrase, as well as a catchy image.

In web applications, it’s necessary to prevent impatient users from POSTing the same data over and over again. For example, to avoid the pain of putting the same item into the basket multiple times because of a browser refresh. To implement that, there’s a good practice, called the Post/Redirect/Get pattern.