What the Heck are Runtime Shared Libraries?

So keeping in the topic from my previous post of low overhead flash apps, I decided to talk a little bit about runtime shared libraries.

So what are Runtime Shared Libraries?
These are libraries that are used just like you normally use your libraries in Flex 3 but instead of storing them within the swf, during runtime it grabs the libraries from a specific place and loads them then. The difference is that if the user has already loaded that library then he/she needs not load it again, resulting in a faster load time.

But, not all libraries are treated equally. There are two different types of libraries, and they are cached in different places.
If the library you use is a typical Adobe one, like the framework.swc library, since it’s signed by Adobe, it get’s cached in the flashplayer itself. This results in a continuous cache throughout other browsers as well, assuming the user doesn’t change his/her security setting for their flash player. Whereas, if you create your own library, which would not be signed by adobe, it’s stored in the browsers cache. This is not bad either since as long as the user doesn’t clear their browser cache they’re good, though it isn’t cross browser.

So there ya have it in a nutshell. For a little more in depth article on this topic visit this article written by Darrell Loverin at the Adobe Developer Center