What is mx_internal?
Well the best explanation is: “mx_internal is a namespace used by the Flex framework to partition out functions and properties that may change in future releases of the Flex SDK.”.
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What is AMF?
AMF in short for Action Message Format, is a binary format for exchanging data. It is most commonly used to transfer data between a Flash or Flex application and a database via a remoting request. In a remoting call, the external elements being called would be application tier services, which would likely be running on an application server such as Adobe ColdFusion, Java, PHP, or .NET.
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What are Modules?
Flex Modules are code functionality compiled to dynamically-loadable SWF files that can be loaded and unloaded by an application at run-time.
Modules let you split your application into several pieces, or modules. The main application, or loader, can dynamically load other modules that it requires, when it needs them. It does not have to load all modules when it starts, nor does it have to load any modules if the user does not interact with them.
Any number of applications can share a module, but a module cannot be run by itself, independently of an application.
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What is difference between MXML and ActionScript?
When you learn Flex there is often confusion between what MXML is and how it relates to ActionScript. We tend to think of it as different entities, but the reality is MXML is just an abstracted form of ActionScript. MXML is a declarative XML syntax that is converted by the compiler into an ActionScript class. This is an important concept to understand because this is the root of why the compiler throws an error when trying to have a MXML file and an ActionScript File with the same name in the same package. The MXML file is really just an ActionScript class and therefore we have a conflicting namespace error.
To help visualize this, imagine the root node of the MXML file is the same as an extends statement. When we use
something like this in MyFirstApp.mxml:
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"> ... </mx:Application>
Means we are saying:
ublic class MyFirstApp extends Application
So why do we need MXML syntax if it just becomes ActionScript. As you are probably well aware, doing complex layout in ActionScript takes a ton of code, especially when you get into the world of nested layout. It can be done in code but why would you want to? XML is all about parent/child hierarchies and by using this as a layout language you can quickly define complex organizational structures that would have taken hundreds of lines of code if you did it all in ActionScript.
How to communicate between Flex and JavaScript?
For communication between Flex and JavaScript we need the ExternalInterface class.
| Method | Defined By | ||
|---|---|---|---|
|
addCallback(functionName:String, closure:Function):void
[static] Registers an ActionScript method as callable from the container.
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ExternalInterface | ||
|
call(functionName:String, … arguments):*
[static] Calls a function exposed by the SWF container, passing zero or more arguments.
|
ExternalInterface | ||
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What is ActionScript?
ActionScript is a scripting language originally developed by Macromedia Inc. (now owned by Adobe Systems). It is a dialect of ECMAScript(meaning it has the same syntax and semantics of the more widely known JavaScript), and is used primarily for the development of websites and software targeting the Adobe Flash Player platform, used on Web pages in the form of embedded SWF files. The language itself is open-source in that its specification is offered free of charge and both an open source compiler (as part of Adobe Flex) and open source virtual machine (Mozilla Tamarin) are available.
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