Stateful vs. Stateless Architecture– Differences, Pros & Cons, Use Cases

What is a Stateful Architecture?

Stateful architecture saves information about the user’s “state” by keeping track of what they do. This information, like login information and user choices, affects how the user feels about the site. Here are some popular examples of stateful architecture:

• Online shopping carts that keep track of what you put in them
• Banking systems that keep track of account information
• Social media sites that display information based on user’s preferences

Now that you know what stateful apps are, let’s talk about their pros and cons.

Pros:

• They use the information they’ve saved to give customers what they want, which increases customer engagement.
• Remember what the user was doing before and pick up where they left off, retaining useful information and improving the customer journey.
• Secure apps save user login and session data, which protects important information.

Cons:

• Developers have to work harder to keep state info, which makes it challenging to develop and maintain stateful apps.
• Creating a stateful app is not an easy task. It’s hard to keep track of state info across instances.
• Stateful apps use more resources, especially memory, and storage, which slows them down.
• In the event of a loss, it is hard to get the application back to the way it was because you also have to recover the lost data.

What is a Stateless Architecture?

Stateless architecture is that architecture that does not save information about previous interactions, user sessions, or events. These architecture do not preserve context or state between requests in a stateless design.

Some examples of stateless architecture are:

• HTTP: HTTP is a stateless internet data transfer protocol. Each client-server request and response is treated independently. Cookies and session management are used to keep user data across requests.
• RESTful APIs: Networked applications often use Representational State Transfer (REST) architecture. RESTful APIs are stateless; thus, each request has all the information the server needs to process it without relying on prior requests.
• Stateless microservices: Stateless microservices perform specified activities without storing state information. Since each instance processes requests independently, adding instances can scale these services horizontally.

Let’s discuss the pros and cons of using stateless architecture.

Pros:

• Stateless apps scale better because each request is processed separately. Adding more application instances without state consistency concerns improves load balancing and horizontal scaling.
• Stateless architecture requires less state management logic, making it easier to design, create, and maintain.
• Stateless architecture doesn’t store state across requests, thus one failure doesn’t affect the others. System fault tolerance improves.

Listed below are some of the drawbacks associated with using stateless architecture:

• Stateless apps must send all data with each request and response, which may increase overhead. Stateless architecture may have lower performance and latency as they do not have to send all the data with each request.
• Chat, gaming, and real-time collaboration apps require state management. These cases may not suit the stateless architecture.
• Stateful activities can complicate stateless apps. Developers must implement mechanisms for managing state across multiple requests, such as cookies, tokens, or databases to manage state across requests.

Differences between Stateful and Stateless Architecture

Stateful and stateless architectures are two fundamental paradigms in software design, particularly in the realm of distributed systems and networked applications. Here's an explanation of both, along with real-world examples:

Stateful Architecture:

In a stateful architecture, the server maintains the state of the client session. This means the server keeps track of the client's data and context between multiple requests. The server remembers past interactions with the client and may use this information to customize responses or maintain the application's state.

Real-world Example:

Consider a traditional web application that requires users to log in before accessing certain features. Once a user logs in, the server creates a session for that user and stores their authentication credentials and possibly other session data like shopping cart items or preferences. Each subsequent request from the user is associated with this session, and the server uses the stored data to provide personalized responses.

Stateless Architecture:

In a stateless architecture, the server does not store any client state between requests. Each request from the client is treated as an independent transaction, and the server does not rely on any past interactions with the client. This makes the server highly scalable because it does not need to manage sessions for individual clients.

Real-world Example:

RESTful APIs are a common example of stateless architecture. When a client makes a request to a RESTful endpoint, it includes all the necessary information for the server to process that request. The server handles the request based solely on the information provided in that request, without relying on any previous requests from the same client. Each request is self-contained, and the server does not maintain any client-specific state between requests.

Comparison:

- State Management: Stateful architectures manage client state, while stateless architectures do not.

- Scalability: Stateless architectures are typically more scalable because they do not need to manage client sessions.

- Complexity: Stateful architectures can be more complex to implement and maintain due to the need for session management.

- Fault Tolerance: Stateless architectures are often more fault-tolerant because they do not rely on maintaining the state on the server.

Choosing between stateful and stateless architectures depends on the specific requirements of the application, including scalability, performance, and complexity considerations.

Use Cases for Stateful and Stateless Architecture

Use cases for stateful architectures

Some real-world use cases for stateful architecture include:

• Stateful architecture includes databases. They store, manage, and track data status. MySQL, Oracle, and PostgreSQL are examples.
• Online gaming platforms require stateful programs to store user session data and game state. Users can save and resume playing. Steam and Xbox Live are examples.
• E-commerce websites, such as Amazon, Walmart, and eBay. To enable users to log in and make purchases, it is necessary to store their session state. Users can add items to their shopping cart, log out, and finish the purchase later.

Use cases for stateless architecture

Here are some use cases for stateless architecture:

• Stateless architecture includes web servers. They respond to inquiries without state information.
• CDNs cache and distribute content without state information. Cloudflare, Akamai, and Amazon CloudFront are some famous examples.
• DNS servers convert domain names to IP addresses without state information. Cloudflare, Google, and OpenDNS are a few examples.