Flash Remoting: The Definitive Guide

Saving and Sharing State

Applications that use Flash for the entire application interface can rely on the Flash client maintaining state while making multiple calls to the server. State in this context refers to data being held in memory in either the Flash client or on the server. Unlike traditional HTML interfaces, where the browser redraws the page for each server request, Flash clients that use Remoting remain as a single stateful instance while handling multiple server requests. As soon as the Flash client is unloaded or reloaded, however, the state that the Flash client held is lost. Flash and Java developers have to work together to preserve the state of the Flash client and restore it when the Flash interface is loaded again.

Additionally, applications that have both HTML and Flash interfaces will often find that they want to share state between the two. One example that we have already discussed is a homegrown security system that uses a User object saved in the user session both to determine if a user is logged in and to retrieve information about that user. A Flash client, the Remoting services it uses, and the code that handles the HTML interface all need to access this user information.

For applications that have Flash-only interfaces, one option for saving state is to use an ActionScript local shared object (an instance of the SharedObject class) to save data to and retrieve data from the user’s computer. Local shared objects are effective as long as the size of ...