The backed's job is to give the frontend what it needs, so at some point it has to make the objects that the fontend will consume and instantiate. That point a

The backed's job is to give the frontend what it needs, so at some point it has to make the objects that the fontend will consume and instantiate. That point at which the two realms join is a source of lots of potential reuse, from model objects, to the business rules surrounding their use and structure. Also consider things like validation, javascript-driven server-side rendering, etc