Constraints provide Grails with a declarative DSL for defining validation rules, schema generation and CRUD generation meta data. For example, consider these [code] class User { String username String password String email int age static constraints = { username size:...

Data transfer object (DTO) is an object that carries data between processes. Working with a remote interface where each call to it is expensive. Response to each call should bring as much data as possible so if multiple request are required to bring data for a...