"State" management for asp.net mvc multi partial view + ajax app

Question

I am trying to convert my asp.net mvc4 app, which had fairly heavy use of SessionState, into a stateless app. I understand that I can store this information in the DB, and intend to do so.

My question, though, is about my particular architecture. My app has a main 'page' consisting of a number of partial view panels, which each have actions in them that can affect the other panels. What i've been doing up to now is storing the entire state of the viewModel (lots of inter-related EF list collections and 'record' objects) in the session, and its been working great. Except when the session just randomly dies.

So, I need to get this data out of the session, and into the DB where I can rebuild the thing at need. My concern is that, if I store the info in the database, every single action done on screen might affect 3-5 different panels, each with their own State updates, thats a minimum of 10 round trips to the DB for every interaction!

What are some strategies I can use to make this idea more scalable?

EXTRA INFO

The view in question here is a sort of POS shopping cart system. There are panels for selecting events, selecting/adding items to the cart, editing cart items, selecting contacts, editing contacts, displaying the cart items, displaying the cart 'subtotals', and finally, a panel with a [checkout] button.

Selecting a new event will change the list of available items. Selecting an item to add to the cart will change the cart item list, subtotals, as well as the checkout panel. Same for editing a cart item.

The main concern is how to recover from a lost session, as I've found the built-in asp.net session code too unreliable. My testers have encountered issues with sessions timing out, and then my app not having any kind of recovery process. When its installed on 1500 sites, each with an average of 10 users, its going to be a plague of lost session issues, and I need to combat that before it becomes a real problem.

I agree that I'm not going stateless...wrong choice of words used in a rush. I'm just trying to move that state into a form that I can rely on past the session failure. My main idea presently is to continue using the session as the local cache for the viewModel data, but to have a fallback operation that can rebuild the viewModel from DB if the session one is lost somehow.

Answer 1

I decided to go with a hybrid approach. I'm still using session, but I'm building out a DB 'recovery' option, so that if the session portion is lost, the DB will be able to provide the values needed to rebuild the session seamlessly.

Seems to be working well, so far.

Answer 2

You shouldn't necessarily be using a database to store (what sounds like) data that only needs to be persisted in the short term.

If these changes to the other partials are only relevant in the context of the current "master view," then I would suggest using jQuery AJAX to send off the requests, parse the response JSON and update the other views. Tutorials on jQuery AJAX and ASP.NET MVC are easy to find, if you don't already have the knowledge:

http://www.codeproject.com/Articles/41828/JQuery-AJAX-with-ASP-NET-MVC

This way, you don't need to make a bunch of round trips. If the changes need to be persisted beyond the context of the current view, make ONE round trip to the database to perform the update and then simply update all of the other partials from the in-memory response from the AJAX call.

You don't need to read from secondary storage multiple times when you already have all of the information you need in-memory. Just do the reading and writing once.