Q:

Access without Logging in

Im using GWT, GAE to make a web app.
I looked at a bunch of tutorials regarding implementing a login system but most of those tutorials implement it so it's mandatory to login to access the web app. How would I go about making it so that anyone can access the app but if they want to use account specific functionality, they they have the option of signing up for an account.

A:

There are two parts to it.
First, in your client code you check if a user is logged in. If so, you allow access to the "closed" parts of the app. If not, you show a link/button to login and hide tabs/views that are accessible to authorized users.
Second, in your server code you specify which requests do not require authentication and which do require it. This is necessary if a user somehow figures out how to send a request without using your client code.
For example, in my code some requests have checkSession() called at the very beginning. If no authentication object is found for this user in session, this method throws LoginException to the client. If the authentication object is present, the request continues to execute normally and returns requested data to the client.

