Using the flex framework RSL's in Flex 3 using Ant

Using RSLs will save you over 300kb of your swf filesize. Flexbuilder has build in features to compile your swf using the rsl libraries, but offcourse we are building on our build server using ant. Using the flex frameworks RSL's from ant is easier said then done. Appearantly this Ant mxmlc target does not implement this feature yet. This feature is shipped with the next flex version (Flex 4 Gumbo). The solution after the jump!

So simply adding the RSL to the mxmlc tag in ant does not work:

<runtime-shared-library-path path-element="${FLEX_HOME}/frameworks/libs/framework.swc">
  <url rsl-url="${FLEX_HOME}/frameworks/rsls/framework_3.0.189825.swz"/>
</runtime-shared-library-path>

The easiest (probably not the prettiest) way to fix this is to specify the RSLs in the flex-config.xml file, located in your flex sdk. Simply change the following statement to false to use the RSL.

<static-link-runtime-shared-libraries>true</static-link-runtime-shared-libraries>

The framework RSL is default, but you can also specify to use the rpc and datavisualization RSLs in the same flex-config.xml.

When you are using a build server, change this setting in the sdk on your build server, be aware that all projects that are build by this build server are using the same settings!
You also need to include the compiled libraries next to your compiled swf file. You can find the files in frameworks/libs and frameworks/rsls folders of your sdk. These files are neccessary for people who didn't cache the frameworks libraries yet in their flex player. Don't be fooled if it works for you without the files, you probably have them cached already.