Assignment 1 hint
Wednesday, February 09, 2011
3:18 PM
Note that there are some hidden assumptions in what data you can put where. 
Anything that is a return value from an Async service has to be storable in XML. 
Which means that it has to be storable as text
Which is enabled by implementing the Serializable interface. 
What is serializable? 
Primitive classes: double, etc.
Base data types: String, etc.  
Templates of serializable classes, e.g. List<S>, Map<S,S>, etc. 
Anything you force to implement Serializable. 
This means that:
You can return a List<String> from a service, 
but you cannot return a List<Foo>,
unless your class Foo implements Serializable, 
and your code won't compile until it does!