What I'd like to do is serialize the callback objectFrom your description, what you mean here is to serialize its stub. Stubs are serializable, no problem.
and pass it from A to B using the OutputStream retrieved from the child's Process object.No problem, just wrap it in an ObjectOutputStream.
Googling the topic, I find that long ago there was a class named java.rmi.server.MarshalOutputStream, which one needed to use for this purpose.There was but you didn't need to use it for this purpose.
So my question is can I send that RMI stub to my child process using normal object serializationYes. If you want to cart a codebase annotation around with it, wrap it in a MarshalledObject.