Tapestry source code viewer

A simple implementation of a SourceCodeViewer would be to have a service for adding and listing the source code and a component to display it.

Tapestry: Using ComponentRequestFilter

This example is similar to Securing Tapestry pages with Annotations, Part 1. My use case is to redirect a user to the starting page of a multiple step wizard in case a request is directly made to an intermediate step and the session has not been properly setup. One way to solve this problem (the ugly way) is to add a condition to every entry point in the page

public class MyPage
{
    @SessionState(create = false)
    private ShoppingCart shoppingCart;

    @OnEvent(EventConstants.ACTIVATE)
    Object activate()
    {
        if(shoppingCart == null)
        {
           return Index.class;
        }
        return null;
    }

    @OnEvent(EventConstants.SUCCESS)
    Object doSomething()
    {
        if(shoppingCart == null
        {
           return Index.class;
        }

        .....
    }

The problem with this code is that you have to check this condition for all event-handlers(Form, EventLink etc). A more elegant solution would be to use annotation secured by a ComponentRequestFilter.