Below are some tips and tricks when dealing with serialization between Java and ActionScript. I’ve spent some time and encountered some frustrations (especially when I was too tired) trying to understand why the value is not properly sent over the wire so I decided to document all of my mistakes. Over the time I will edit this post to add new insights

• if something seems wrong turn on debugging in services-config.xml
• a property must have a public getter and setter in order to be serialized. I know that is strange (why should I have a setter when it’s not needed?) but that’s it. I do not like it all because sometimes it breaks encapsulation
• you should take care to map the ActionScript class with the corresponding Java class using the metadata. For example [RemoteClass(alias="com.foo.model.MyClass")]
• verify that the ActionScript object is included in the SWF file. If your project does not have a reference to the AS file then it will not be included in the resulting SWF so the Java class will be serialized to a generic object
• you cannot serialize maps that have integers as keys See this bug
• when serializing Hibernate entities be sure that all of them are initialized or use some kind of Open Session in View pattern - or better build a value object to contain only the data you really need.
• a NULL number in Java is converted to 0 in ActionScript
• a Long number from Java cannot be properly converted to Number in ActionScript - you will lose precision, so you should send it packed in a different way

From http://cornelcreanga.com/