JAX-RS annotations aren't really composable - functions usually are, although I haven't looked at the Spark implementation to find out. With plain functions if

JAX-RS annotations aren't really composable - functions usually are, although I haven't looked at the Spark implementation to find out. With plain functions if I need to wrap requests or responses I just wrap the functions. With JAX-RS I need to find or write an appropriate annotation or start adding filters. With plain functions I can share behaviour between resources by sharing functions.