The SARDeployer uses the archives="*" to mean that all of the archives (compressed and exploded) in the codebase directory should be added to the classpath.
If you want the codebase directory added to the classpath then leave out the archives attribute.
If the codebase specified url contains resources and not archives then do not use the archives attribute.
In your example where the myresource.txt is in C:/commonresources this would look like:
<classpath codebase="file:/C:/commonresources/" />