The definitive guide to building a scalable software

Have you ever felt frustrated when you couldn’t immediately access a specific website? You needed to send an email quickly, order some goods, make a bank transfer, but the platform slowed down, and you had to wait without knowing when everything will work again.

Now imagine that this is your product and your customers who are getting annoyed when using it.

Let’s assume you’ve built a new software product and started getting some users. Later on, your marketing campaign attracts new customers, and after a while, thousands of people begin using your product. Suddenly, at one point, they’re unable to access the system. So what’s the problem?

As the number of users increases, it may lead to a low response time for the system. Problems with scalable software can be one of the reasons. Simply put, the load reaches the point when the server is not ready to stand a growing audience. Multiple requests and operations processed at the same time result in a high load on your server. If the architecture is misdesigned, the server eventually burns out, and the system crashes. The result? Service unavailability, system crash, random errors, slow content loading, etc. Many users will stop using your product, damage your brand reputation, and the business can lose many opportunities.

In this article, I will identify the main principles of scalable software and what affects product scalability.

What is scalability?

Scalability can be defined as the capacity of a system to handle rapid growth. In other words, if one day a million people around the world have decided to use your product, you can sleep soundly knowing that you have a truly scalable product ready to cope with it. If the product is non-scalable, there will be delays in product functionality, and the entire user and customer experience can suffer greatly. Oh, and be ready to stock up on coffee as you will have a lot of work to make things work again.

When the product is scalable, it allows adding extra resources while keeping the structure of the central node intact. This is one of the most important indicators of a successful software product.

Software scalability allows your business to remain stable despite the volatile nature of the industry. With a reliable product, your business can benefit with higher agility and cheaper upgrade expenses in the long run.

However, scaling is still a challenging process. Building scalable software means you have to be more meticulous with the development details.

What affects software scalability?

Achieving scalability is not a trivial task. One of the biggest challenges is to determine how many concurrent users your system can support. Before you make improvements or do capacity planning, you must identify factors that influence performance and scalability.

• Architecture is one of the most important parts of system scalability. An organized software architecture makes it easy to maintain product quality, which further enhances the software. Every aspect of the software architecture requires consideration, including ways in which the runtime of hard-hit areas can be reduced or ways in which caching can be made just a bit smaller to ease the memory footprint. From this point of view, developing a scalable system architecture is more of an art than a science.
• Another important thing that affects software scalability is sustainable load testing. It measures the software performance under the maximum load at which the system would crash. The aim is to identify the peak point after which the users won’t be able to access the system. Proper loading testing is a way to identify and eliminate the bottlenecks of the software and ensure its smooth growth.

The architecture of a scalable software

Now let’s focus on the main principles of scalable software.

Horizontal scaling

Horizontal scaling is elastic and dynamic. It is often easier to scale dynamically by adding more machines into the existing pool. You can keep your existing resources online, and add as many servers as you want. Since each of them is independent, it causes no harm.

Vertical scaling

Vertical scaling is scaling by adding more compute power (CPU & memory). It’s secure and fast under light loads, but it does not scale well at all. Scaling beyond that capacity often involves downtime and comes with an upper limit.

Cloud storage

Scalability on the cloud eliminates the need to predict future capacity requirements; should a customer demand more resources, they can be quickly added.
With cloud storage, you only pay for the resources that you use. You can grow and shrink the available resources per your needs and be charged only for space that you are using.

Physical servers

To expand a physical server environment, you need to buy additional hardware components, which can be very expensive to build, maintain, and secure.
New projects have to be put on hold while waiting for the storage to be finished. In addition, there’s always the risk of hardware becoming outdated.

Microservice architecture

As the complexity of the system increases, the size of the teams that work on it also increases. Having the system as a monolithic one inhibits the development team from being able to move forward at speed. This gave rise to the need for an approach that would allow independent functional teams to be able to deliver their functionality in its entirety with minimal dependency on other teams.
The microservice architecture breaks large software into smaller pieces that can operate independently of each other. When one node is in high demand others can work without adding to its load.

Monolithic architecture

The monolithic architecture is considered to be a traditional way of building software products. Normally, monolithic applications have one large code base and lack modularity. So, when it comes to scalability, you can’t scale components independently, only the entire application.

If you are unsure whether your project needs to scale or not, our team will gladly provide you a free consultation. It’s an essential part of our working culture: make every cooperation with customers as effectively as possible in all respects: time, resources, and costs. Given that scalability is costly, we won’t impose this on you if your product doesn’t need it.

Cloud vs. physical servers

When you need to decide which server is best for your business, there is a lot to consider. While both cloud and physical servers perform similar functions like storing, sharing, and protecting data, there are crucial differences in user experience, costs, and time frames. If your business has outgrown the physical server or is expanding its geography, you may consider moving to a cloud server.

Let’s look at some factors that will help you decide whether to go with a cloud service provider or a physical one.

Cloud servers

A cloud server is a virtual server that is built, hosted, and delivered via a cloud computing platform. With cloud servers, you can optimize IT performance without the huge costs associated with purchasing and managing fully dedicated infrastructure.

Pros

• Data backup and restore. Once data goes into the cloud, a copy is instantly made and transferred to a remote location. With an internet connection, you can easily access and retrieve data from anywhere.
• Storage can be added as needed and you only pay for what you need. If you’re expecting a large amount of traffic, all you have to do is scale your resources up during the traffic surge and down once traffic levels return to normal.
• No need to worry about updating and maintaining your server — cloud solution providers do it for you. While you’re focusing on your business, your server stays up to standard.

Cons

• If the Internet goes down, you won’t have access to any of your information.
• If your business isn’t dependent on uptime and instant data recovery, the costs could outweigh the benefits.
• Moving from legacy systems can be costly. They also take time, which affects operations.

Physical servers

A physical server is purchased or rented entirely for your own business needs. A physical server consists of separate computer units, equipped with their own hardware and external devices. With physical servers, businesses still need the IT capacity and expertise to manage ongoing maintenance, patches, and upgrades.

Pros

• Having physical control over your backup.
• Being able to keep critical data and information in-house with no 3rd party access available.
• No need to rely on an Internet connection to access data.
• It can be more cost effective for small and mid-sized companies.

Cons

• No recovery time or uptime guarantees.
• Servers take up space. They need a secure location, power, and cooling in order to run effectively and efficiently.
• Leasing servers can help offset some of the costs, but you still need someone on the ground who can manage your data center.

When deciding whether cloud or physical servers best match your organization, it’s important to consider factors such as timelines, compliance requirements, the consistency of your workload demand, internal staff talent, and more.

Building a scalable software system: my experience

For my client, a dating platform, my team and I created a scalable software system to handle peak loads. The client required an infrastructure that would manage high amounts of web traffic and scale seamlessly to varying loads. Our task was to build a microservice architecture, where each microservice is responsible for some domain parts of the system. It would allow us to meet the rising demand for a platform and distribute the load. As a result, the client focused on work that improves product functionality rather than just maintaining the platform. Additionally, the system maintainability has been increased and resource overheads reduced.

To get into project details, read more in case study.