Mastering Session Management in ASP.NET Core with NCache

By Waqas Anwar

Introduction

HTTP is a stateless protocol, meaning that the web server does not retain the user's state between requests. This limitation can present significant challenges for web developers. To overcome these challenges, developers often use solutions such as appending query strings to URLs, storing cookies on client machines, or saving user session information on the server. In this article, I will provide a brief overview of session management, discuss its limitations, and explain the use of distributed caching solutions for effective state management in large-scale applications. Additionally, I will offer practical guidance on installing, configuring, and using a distributed cache in ASP.NET Core web applications.

Overview of Session Management in .NET

Session management is one of the key features of any web application. It allows the server to save user-specific data such as authentication status, shopping cart information, etc., and the server to track users across multiple requests. Sessions data is typically stored in server memory or disk but can also be stored in a distributed cache for scalability and reliability. Each user is assigned a unique session identifier called a session ID, which is stored in a cookie or passed in the URL. This session ID is then used to retrieve the session data on subsequent requests.

1. In-Process: The session data is stored in the web server's memory. This is the fastest option, but it is not very scalable because session data is available memory, and it can easily be lost if the application pool is recycled or if the web app is hosted on multiple servers and a load balancer sends the request to another server.
2. State Server: The session data is stored in a dedicated state server, separate from the web server. This allows session data to persist even if the application pool or web server is restarted. The State Server runs as a Windows service, and session data is accessed over the network, making it suitable for load-balanced environments. However, using a State Server can introduce network latency compared to in-process session storage, though it improves scalability and session persistence.
3. SQL Server: The session data is stored in an SQL Server database, which provides persistent storage if you are using multiple web servers or have a load-balanced environment. This approach is more resilient than in-memory sessions but it can introduce overhead due to database read/write operations. This is the best option if your application requires high availability, data persistence, and scalability, and you can slightly compromise on performance.
4. Distributed Caching: Distributed caching is a method of storing data across multiple servers or nodes in a network, allowing web applications to access cached data more efficiently and reliably. This method is more suitable in cloud-native and distributed applications where you want to keep cached data on the server that is nearest to the user.