Create an ExtensionContext instance

The extension ID
The context type

To begin working with the native implementation, the ActionScript extension class uses the ExtensionContext static method createExtensionContext() . This method returns a new instance of the ExtensionContext class.

package com.example { 
    public class TVChannelController extends EventDispatcher { 
 
        private var extContext:ExtensionContext; 
 
        public function TVChannelController() { 
            extContext = ExtensionContext.createExtensionContext( 
                            "com.example.TVControllerExtension", "channel"); 
             
        } 
        . 
        . 
        . 
    } 
}

In this example, the constructor calls createExtensionContext() . Although your extension classes can call createExtensionContext() in any method, typically a constructor or other initialization method calls it. Save the returned ExtensionContext instance in a data member of the class.

Note: Calling createExtensionContext() as part of a static data member’s definition is not recommended. Doing so means that the runtime creates the extension context earlier than the application needs it. If the application’s execution path does not eventually use the extension, creating the context wastes device resources.

The method createExtensionContext() takes two parameters: an extension ID and a context type.

The extension ID

The method createExtensionContext() takes a String parameter that is the identifier, or name, of the extension. This name is the same name you use in the extension descriptor file in the id element. (You create the extension descriptor file when you package your extension). The application developers also use this name in the extensionID element in their application descriptor file. If an extension with the specified name is not available, then createExtensionContext() returns Null .

To avoid name conflicts, Adobe recommends using reverse DNS for an extension ID. For example, the ID of the TVControllerChannel extension is com.example.TVControllerExtension . Because all extensions share a single, global namespace, using reverse DNS for the extension ID avoids name conflicts between extensions.

The context type

The method createExtensionContext() takes a String parameter that is the context type for the new extension context. This string specifies more information about what the new extension context is to do.

For example, suppose the extension com.example.TVControllerExtension can manipulate both channel and volume settings. Passing "channel" or "volume" in createExtensionContext() indicates which functionality the new extension context will be used for. Another ActionScript class in the extension, such as TVVolumeController, could call createExtensionContext() with "volume" for the contextType value. The native implementation uses the contextType value in its context initialization.

Typically, each possible context type value you define corresponds to a different set of methods in your native implementation. The context type, therefore, corresponds to what is, in effect, a class in your native implementation. If you call createExtensionContext() multiple times with the same context type, typically your native implementation creates multiple instances of a particular native class.

When the context types of multiple calls to createExtensionContext() are different, the native side typically performs different initializations. Depending on the context type, the native side can create an instance of a different native class and can provide a different set of native functions.

Note: A simple extension often has only one context type. That is, it has only one set of methods in the native implementation. In this simple case, the context type String parameter can be Null .