An app can either be in stateful or stateless condition. An app’s state is the condition it is in at a given time. An app, being in a stateless or stateful state, depends on the interaction period, if the information is being recorded, and how the information is stored. This guide explores the main differences between stateful and stateless apps.

What is a stateless application?

A stateless app does not save the client’s information generated in one session to b used in the next session with the same client. Every session is treated like a new session, and the processes are not dependent on previous interactions.

In a stateless state, the server doesn’t keep data or details about the client’s interaction. Instead, the data is moved to the server after the client’s interaction. This approach is significant when developing offline apps.

Advantages of Stateless apps

Both stateless and stateful apps have their pros and cons. Below are the advantages of a stateless app.

• Scalability & horizontal expansion

It is easy to scale and expand a stateless app since all requests and interactions are independent. They don’t need shared server resources to execute the processes. This simplifies the process of distributing workload on different servers, thus enhancing growth in user demand.

• Improved performance

Since a stateless app doesn’t rely on previous sessions or interactions, it performs better. Every independent request can be processed on the go, giving room to immediate responses in a seamless manner, thus enhancing overall performance.

• Ease of deployment & maintenance

The process of deploying and maintaining stateless apps is simple and seamless. It is easy to remove or add servers without affecting the entire system on how it makes updates, behaves, updates patches, and upgrades.

• Fault tolerance and reliability

There is no need for data synchronization in a stateless app. This makes the app fault tolerant and its availability. Ideally, if a server malfunctions, another server will take over the processes to ensure a continuous process and resilience.

• Load balancing flexibility

Since each request is independent of stateless apps, the loading balancing is simplified. The load balancers simply allocate all the incoming requests to available servers without worrying about the session’s nature, thus creating a flexible and scalable way of controlling server resources.

Disadvantages of stateless apps

So, what makes a stateless app not an ideal option? Below are some of the downsides of a stateless architecture:

• Data repetition

In stateless apps, a client must input new data in every request, and this can lead to the repetition of the same data.

This can cause poor performance, especially when handling recurrent interactions or when dealing with huge payloads.

• Additional security considerations

The stateless approach requires extra security protocols to promote the confidentiality of each session’s information. Otherwise, the system will be exposed to different forms of security threats. Cryptographic and secure token techniques are examples of extra security measures to put in stateless architecture.

• Loss of session context

Stateless systems don’t keep information from one session to the other, prompting clients to enter new details when processing a new session. This creates a complex pattern, and it includes extra overhead.

• Increased network traffic

With each client processing new requests, network traffic increases significantly, thus affecting the overall performance, especially when handling and processing huge data volumes.

Examples of stateless apps

While stateless apps have their best and downsides, they can be used in different ways, including the following:

Vending machines – every transaction is independent and does not rely on other future transactions.

Researching online– every search activity is unique in its own way. A broken search session means starting again from scratch.

What is a stateful application?

Contrary to stateless architecture, a stateful system allows users to record, store, and return data on previous interactions through the internet.

The server on a stateful system, therefore, keeps track of user interactions and stores the client’s information and interaction activities for future requests.

A client can there’re return and use the details from the previous session without having to start from scratch.

In a stateful app, the sessions or interactions are dependent on one another. The current interaction can be impacted by what happened in the previous sessions. Therefore, every interaction uses the same server in a stateful architecture. This makes it easy to retrieve and reuse the information from the previous interaction, which could not be possible if different servers were used as in the case of a stateless architecture.

Advantages of a stateful architecture

Like Stateless architecture, a stateful system has a set of pros and cons. Below are some of the top benefits of stateful architecture:

• Better caching opportunities

Stateful architecture has the best caching mechanisms, enhancing data storage for each session or interaction with the system.

The ability to cache data at serve levels enhances overall performance and minimizes backend resource loads.

• Data integrity & consistency

Stateful systems maintain a high level of data integrity and consistency since they maintain all the interactive activities during a session. This is an important aspect, especially with systems that require complex processes.

• Efficient resource utilization

There is no repetitiveness in stateful architecture. By keeping the client’s information during a session, clients don’t need to perform the same tasks over and over again, thus minimizing resource exploitation, a move that promotes scalability and performance.

• Enhanced user experience

Since a stateful architecture has details of previous interactions, it can recall user behaviors and patterns and then personalize the services to deliver a smooth user experience. This is especially a viable idea for systems such as multimedia streaming, shopping carts, or simply systems that require user authentication.

• The simplicity of development

It is easy to develop a stateful architecture since the developers can easily access user details during a session. This makes it possible for developers to modify and tailor the app to align with user needs.

Disadvantages of stateful architecture

Some pitfalls of a stateful architecture include the following:

• Difficulty in load balancing

It is a complex process when distributing incoming requests to servers within a stateful system since the system requires maintaining the session’s activities.

• Fault tolerance and high availability

To enhance fault tolerance and availability in stateful architecture, there must be other measures put in place. This calls for session state synchronization for different servers, a move that is complex and can lead to system failure.

• Scalability challenges

It is hard to scale a stateful architecture. The more the clients, the more exploitation of the server’s memory. As the server’s memory gets overwhelmed with many requests, it can limit some other users and lead to poor performance issues, making it hard to scale an app.

Examples of stateful apps

Below are the best stateful architecture application examples

Online banking apps – these apps depend on stateful architecture to keep client’s details for easy retrieval on the next transaction. Again, all activities within a user account need to be secured for easy reflection on the next activity, hence the need for stateful architecture.

Email platforms – they use stateful architecture to keep users logged in, allowing access to new and past email activities without prompting the user to log in once more.

E-commerce platforms – The stateful architecture is useful in e-commerce platforms for maintaining browsing history shopping cart details, creating a personalized experience, and promoting user preference services. All these details are effective in enhancing a smooth purchasing process.

Online gaming platforms – they rely on stateful architecture to keep user activities and data on a specific gaming activity. With a stateful architecture, it becomes easy for gamers to save their progress and resume later.

Stateful vs. stateless application: Differences

The main difference between stateful and stateless applications is that while stateful architecture stores data, stateless architecture does not store data.

The activities in a stateful architecture are dependent on past history and interactions. In a stateless architecture, on the other hand, each session is independent. There is no connection between the current activities and the past activities.

In a nutshell, stateful applications are apps for database storage. Examples include PostgreSQL, Oracle, and MySQL.

Stateless applications, on the other hand, are simply web servers that respond to requests. Examples are OpenDNS, Google, and Cloudflare.

Other key differences between stateful and stateless architecture include the following:

• Ease of implementation

It is easy to implement stateless processes because they require less storage, less logical reasoning, and fewer actions to determine the type of request.

Stateful processes, on the other hand, require more storage and more computer brain power to implement. Therefore, the stateful processes and complex and hard to implement compared to stateless processes.

• Server complexity

The server design of stateless architecture is simple because the processes do not rely heavily on the servers to execute processes.

Stateful architecture, on the other hand, keeps the details of every activity, hence bulking the servers with more tasks to free space on the client’s side.

Therefore, servers are more complex in stateful architecture than in stateless architecture.

• Crash & system failure management

Sometimes, the system fails. However, the response to the system’s failure differs depending on whether the architecture is stateful or stateless.

Of course, a system failure has harsh consequences including loss of data if not well managed. That is why each system has a set of protocols to follow when handling systems’ failure and crush.

The stateful architecture stores information on previous activity in a specific state. This means that the server must remain stable and active throughout. Therefore, should a system crash or fail, losing data in a stateful architecture is inevitable, contrary to the stateless architecture.

• Client-server dependency

All apps are two-sided (client side and server side) when it comes to data transmission and data exchange. The degree of dependency is what varies depending on the protocols put in place.

Stateless architecture embraces independence protocols. The degree to which it depends on client servers is minimal, thus giving the servers enough space to execute other tasks.

This is contrary to stateful architecture, which relies heavily on the client and server sides to execute the processes. Every request sent to the server requires an immediate response before establishing a connection. Should the request fail from either side, it means re-sending the request again.

Therefore, there is much more client-server side dependency in stateful architecture than in stateless architecture.

• Scalability

It is easier to scale services in stateless architecture than in stateful architecture.

With auto-scaler tools, you can scale down or up automatically in a stateless architecture. Besides, you can make any server handle and process requests by adding backend servers to frontend to balance the load.

This is contrary to a stateful architecture, which requires the manual addition of stateful servers and services to scale the services, thus making it complex to scale the services.

• Response mechanism

The processes of sending requests and responses differ in stateful and stateless architecture. In stateless architecture, the client initiates the request to the server. Once the request is sent, the client doesn’t need to perform any other action since they don’t expect a response.

In a stateful architecture, on the other hand, there should be a connection between requests and responses to make the whole process complete. If the request is not complete, the user has to send another request to get a response.

• Multitasking capabilities

The system can process multiple data processes and retrieve data simultaneously depending on its state. Ideally, it is the server that can handle multiple requests and processes.

Stateless architecture doesn’t depend on the server since every request is independent. Therefore, as long as the resources are available, the requests can be processed. There is no dependency on already existing data.

This is contrary to the stateless architecture, which relies on the same server or resource to process requests and retrieve responses. The server must access stored data to process current requests. Therefore, unless one session is over, no one can process more requests.

• Performance Speed

When choosing a function or service, speed is one inevitable consideration. Some apps are faster, while others are slower. The variations depend on the protocols and processes the applications follow to perform actions.

Stateless systems don’t store data in their servers, and they can process different tasks on the go without depending on another system for information. This means that processes and tasks are performed at a high speed in stateless architecture.

Stateful architecture, on the other hand relies on the information on the previous actions to process requests and responses. This means only limited actions and requests can be processed on the go, thus a much slower speed compared to stateless architecture.

• Servers’ specifications

The server specifications in stateless architecture are flexible enough, allowing the system to process multiple requests on the go. Ideally, more servers can process a single request because requests are not limited to specific servers.

This is contrary to stateful protocols where the same server must process the existing request until done, thus less flexibility as compared to the stateless architecture.

Stateless vs stateful applications: which one should you choose?

While many services are opting for stateless apps to produce highly scalable and flexible apps faster, choosing between stateless or stateful applications has its set of advantages and disadvantages.

Before you choose either stateful or stateless applications, weigh the following:

• Requirements of the projects
• Benefits of using a stateless and not stateful approach
• Challenges you are likely to experience
• The goals you want to achieve

Conclusion

Stateful and stateless applications both have significant impacts on app development. While they have similarities in database system use cases and firewall use cases, they have big differences that distinguish one from another. While one is good in one instance, the other one isn’t a viable solution.

It is upon an organization to evaluate its needs in terms of performance, scalability, flexibility, and speed requirements before selecting the ideal architecture for its applications.

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