architecture – Finding the best design approach for a system

I want to develop a server-side application that can store (in session, no database or file storage) a single list / table for each user session, and then I want to be able to process CRUD operations on this list / table for as long that the session is alive.

What I want to learn is what would be the best approach to develop such an application? I wanted to have a RESTfull service for this, but I think storing the array in a session is a violation of RESTfulness. If I want to have a RESTful service for an application, how can I implement such a feature? Which architecture should I apply?

Any help would be appreciated.