Difference between Value Object pattern and Data Transfer pattern

Question

In which scenario can I use those design patterns in n-tier architecture?

Answer 1

A value object is something that is useful to encapsulate as an object, but it has no identity. Compare it to an entity, which is something that does have identity. So in an order-processing system a Customer or an Order or a LineItem are concepts that point back to specific people or things or events, so they are entities, where a value object is something like a monetary amount, that doesn't have an independent existence of its own. For instance, for a system where part of the application involved calculating how to divide a payment between different accounts, I created an immutable Money object that had a divide method that returned an array of Money objects evenly splitting the original object's amount across them, that way the code for dividing amounts was in a place that was handy where the person writing the jsp could use it, and they didn't have to mess up the jsp with non-presentation-related code.

A Data Transfer Object is a wrapper for bundling things together for sending across application tiers or layers. The idea is that you want to minimize the amount of network back-and-forth traffic by designing methods that send large bundles of information.