Recipe 17.8. Controlling the Size of Local Shared Objects

Problem

You want to control the amount of disk space used by a shared object.

Solution

Use the Security.showSettings( ) method or visit the web site for the Flash Player Settings Manager.

Discussion

As mentioned in Recipe 17.8, the default size for an LSO is 100 KB. Recipe 17.3 explained that the flush( ) method can be used to request a certain amount of disk space for an LSO. If the disk space requested exceeds the maximum allowed value, the user is prompted to either allow or deny the request. Through the use of the flash.system.Security.showSettings( ) method, it is possible to bring up a dialog that allows the user to set the maximum amount of data allowed to be stored in an LSO. The following code opens the Settings UI to the local disk storage section.

// Show the settings for local storage Security.showSettings( SecurityPanel.LOCAL_STORAGE );

To coincide with the Settings UI for a specific domain, there is a more comprehensive Settings Manager that allows a user to change to global settings. Athough the Settings UI and Settings Manager provide similar functionality, they are completely different items. The Settings UI is a special form inside the Flash Player that is displayed via the showSettings( ) method, allowing the user to control the settings for a specific domain. The Settings UI can be opened through ActionScript as the preceding code block shows. It can also be opened manually by right/Control-clicking inside the Flash Player, and then selecting Settings from the contextual menu. In contrast, the Settings Manager is accessed via the macromedia.com web site. To open the Settings Manager to the Website Storage form, go to http://www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager07.html.

This URL may look like just a simple a web page or screenshot, but it's actually a functional Flash application that modifies the global settings of the Flash Player. Updating a value via the Settings Manager URL affects how the Flash Player behaves. For instance, if you want to change the default size of an LSO (for LSOs that have not been initially created yet), navigate to the Global Storage Settings page (http://www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager03.html).

Adjust the slider until it displays an acceptable value to you. After the slider value has been changed, the default maximum size for LSOs has been modified.

Remember, as a developer you have no control over LSO disk space on a client's computer. The best you can do is request a certain amount of space, explain why you might need that space, and hope that the user grants it to you. It is not recommended, however, to rely on LSOs for functionality critical to your application because the client has the final say of the LSO sizeif the LSO is even allowed at all.