Key points to learn Apache Royale
Here are some things you may need to know to help you be more productive with Royale, although some folks get pretty far by just following the tutorial in Create an Application and extending it.
Royale uses both a declarative markup language called MXML and a scripting language called ActionScript that is like JavaScript, but with classes, interfaces and types. This allows you to more efficiently declare the static portions of your application and write up the dynamic portions in a language where the compiler can catch more errors sooner.
Royale provides a variety of component sets, each tuned towards different applications requirements. Components are designed with a “Pay as you go” philosophy. Only the most common functionality is built into the component, and other options are added as plugins called Beads. Components designed this way use to be small and fast, and don't have lots of built-in customization options that will never use most of the times. You can read more about PAYG here.
The underlying component patterns in most Royale components rely on a plug-in model. Instead of making large component classes with lots of code baked in, each individual feature of a component is designed as its own class with an interface marking it as a “Bead”, and then the component itself is called a “Strand” and Beads are placed on the Strand to compose a Royale component. You can read more about Strands and Beads here.
Sometimes you may want your Royale application to call an external piece of JavaScript that is also hosted in your web page, or even for some extenal JavaScript from your page to call into the Royale application. In the Flex (and Flash) world, there was the possibility to use the ExternalInterface class to achieve this functionality. If you want this in Royale, there are some options available that you can read about here.
Another option are externs, wich is uses Google Closure Compiler (GCC){:target=‘_blank’} to declare that a name for a class, property or function is defined in external code and so should not be renamed when application code is compiled. Apache Royale can use the properties of the external library, and you can even see them as options if you are using an IDE, with code intelligence enabled. read about here.