I have a web application developed using Spring - Struts framework deployed in tomcat 8 server. The application is hosted in only one server.
The application code is layered like
Action | BPO | DAO | DTO | EntityObject
Serializable is used by
java.io and it's needed if you want to keep the objects in session. Some other frameworks is using
Serializable behind the scene to perform serialization. If you don't know where the object is serialized using
java.io.Serializable you better add this interface to DTOs.
The client-side might use other serialization like JSON, XML, etc., but it doesn't affect the processes running serialization on server-side and it should be handled separately by your code or some other framework like Struts or Spring, doesn't matter.