I believe this is a solved problem, although it's not used much. EOF and Apache Cayenne are ORMs that have a notion of a hierarchy of 'editing contexts'. If yo

I believe this is a solved problem, although it's not used much. EOF and Apache Cayenne are ORMs that have a notion of a hierarchy of 'editing contexts'. If you save to the top-level one, it commits to the schema. But you can create a 'child editing context'. You can then interact with this graph. When you commit it, it gets pushed up to the parent editing context. Of course, if you want you can them commit again to persist it. This allows you to build and throw out a deck. This creates a new problem, a human one. People are used to interacting with web applications, and having everything saved somewhere after each screen change. With this arrangement, stuff doesn't necessarily get saved. I built an application that allowed you to create an order, and then create a person associated with it, and all this in memory. Users were annoyed that when they didn't save the order, the people they'd created associated with it also got thrown out.