Stateful vs Stateless Architecture

Introduction

Hi, Folks. In 2023 architects and engineers face constant challenges to design efficient, scalable, and reliable applications. When it comes to designing a system that can scale to millions critical decisions they must make is choosing between two fundamental architectural paradigms stateful & stateless architecture.

In this article, Today we will explore the key difference between stateful and stateless architecture. Moreover, we will examine the impact of stateful and stateless design on application performance, resource utilization, and scalability.

“To create one must first question everything.”
-Eileen gray

Before, Jumping into the computer jargon, let's understand the meaning of stateful & stateless applications.

Stateful Application

A stateful application is a program that saves client data from the activities of one session for use in the next session. The data that is saved is called the application’s state.

Example

let us look at an analogy. Consider the scenario of a telephone call. In this case, the connection is maintained from the beginning to the end of the call to ensure continuous communication. The connection is validated first, and only then will the session be established indefinitely until the end of the talk.

An example of stateful is FTP (File Transfer Protocol). For the course of an FTP session, which often includes many data transfers, the client establishes a Control Connection. After this, the data transfer takes place.

Stateless Application

A stateless application doesn’t save any client session (state) data on the server where the application lives. There is no stored knowledge of or reference to past transactions. Each transaction is made as if from scratch for the first time.

Example

let us consider the event of sending an Email. Here, the receiver’s availability is not confirmed, and the sender just sends the Email to the recipient. There is no confirmation from the receiving device to the sending device that the message has been received.

A stateless protocol is one in which the receiver is not required to keep the session state from previous requests. The sender sends the relevant session state to the receiver in such a way that each request may be interpreted without reference to prior requests’ session state, which the receiver retains.

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I hope. now you all are clear on what stateful & stateless applications mean. Let dive into what are the pros & cons of each architecture.

Advantages of Stateful Architecture

1. Stateful protocol keeps track of the connection information, and as a result, delivers superior performance because of continually keeping track of information.

2. Stateful protocols are more intuitive because they can maintain data on the server between two requests.

3. They can improve performance when data retrieval is required only once.

Disadvantages of Stateful Architecture

1. The stateful protocol requires memory allocation in order to store data. In the event of inefficient maintenance of session storage, there can be a decrease in performance.

2. It requires continuous management of the service’s full lifecycle. These protocols are highly dependent on the server-side state.

3. Usually, stateful protocols require backing storage. Since the state is maintained, stateful is not very secure.

Advantages of Stateless Architecture

1. It is easier to recover from partial failures like crashes since no state is maintained, which improves reliability.

2. The server does not have to store the session state between requests, hence, scalability is enhanced as deploying the services to any number of servers is possible, and implementation is simplified even more.

3. In Stateless Protocols, each individual connection is disconnected after each request-response cycle

Disadvantages of Stateless Architecture

1. It may be essential to include additional information in each request, and as a result, the server will need to interpret this new information.

2. They may degrade network performance by increasing the amount of repetitive data delivered in a series of requests, which cannot be saved and reused.

Stateful vs. Stateless: Which Is Best?

The decision to use stateful versus stateless apps boils down to your scalability requirements and what you need the app to do. If your app needs to store session data to process transactions in context and if the server can handle the expected processing load, a stateful system is probably best. On the other hand, if you are building an app that needs to process REST API transactions, and provide information in response to client requests – and traffic levels can grow exponentially – a stateless app is what you’ll be working with.

Conclusion

I Hope, the difference between stateful and stateless architectures is now much clearer. Use this knowledge to build a highly reliable & scalable application for future-generation users.

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