Scalability has always been a primary factor while designing a solution. If you ask any enterprise about their solutions, scalability will be one of the key considerations. Scalability refers to allowing your system to handle growing workloads, which can apply to multiple layers, such as the application server, web app, and database. Scalability helps you fulfill user demand without impacting application performance, resulting in higher business returns.

As most applications nowadays are web-based, let’s also talk about elasticity. This is about growing your system by adding more capabilities and shrinking it to save on unnecessary costs. With the adoption of the public cloud, it has become easy to quickly grow and shrink your workload, with elasticity now replacing scalability.

Traditionally, there are two modes of scaling:

• Horizontal scaling: Horizontal scaling is becoming increasingly popular as computing power has...

Creating a highly available and resilient architecture involves designing systems that can tolerate failures of individual components without disrupting the overall system functionality.

Highly available architecture

The one thing an organization wants to avoid is downtime. Application downtime can cause a loss of business and user trust, making high availability a primary factor while designing the solution architecture. The principle of high availability is “design for failure, and nothing will fail.”

The requirement for application uptime varies from application to application. If you have an external-facing application with a large user base, such as an e-commerce website or social media platform, 100% uptime becomes critical. In the case of an internal application (accessed by an employee, such as an HR system or a company intranet), it can likely tolerate some downtime. Achieving high availability...

High availability means your application is available to the user but it can result in degraded performance. Suppose you need four servers to handle users’ traffic. For this, you put two servers in two different physically isolated data centers. If there is an outage in one data center, user traffic can be served from another. But now you have only two servers, which means only 50% of the original capacity is available, and users may experience performance issues. In this scenario, your application has 100% high availability but is only 50% fault tolerant.

As shown in Figure 2.6, to achieve 100% fault tolerance, you need full redundancy and have to maintain the double count of the servers so that the user doesn’t encounter any performance issues during the outage of one zone.

Figure 2.6: Fault tolerance architecture

Fault tolerance is handling workload capacity if an outage occurs without compromising system performance...

With the availability of fast internet, customers are seeking high-performance applications with minimal load time. Organizations have noticed that a direct revenue impact is proportional to application performance, and slowness in application load time can significantly impact customer engagement. Modern companies are setting high expectations when it comes to performance, resulting in high-performance applications becoming necessary to stay relevant in the market.

Like resiliency, the solutions architect needs to consider performance at every layer of architecture design. The DevOps team needs to put monitoring in place to check that the solution continues to perform effectively and work to improve it continuously. Better performance means increased user engagement and return on investment.

High-performance applications are designed to handle application slowness due to external factors such as a slow internet connection. For example, you may have...

Organizations make a significant capital investment in hardware and develop the practice of regularly refreshing it with a new version of the application and configuration. Over time, this can lead to different servers running in varied configurations, and troubleshooting them becomes tedious. Sometimes organizations must keep running unnecessary resources when they are not needed, as they are unsure which server to shut down, which may cause application failure. The inability to replace servers makes rolling out and testing any new updates in your server fleet challenging. These problems can be solved by treating your server as a replaceable resource, which enables you to move more quickly to accommodate changes, such as upgrading applications and underlying software, resulting in less downtime and fixing application issues quickly. That is why, while designing your application, you should always think of immutable infrastructure. This means that,...

A traditional application is deployed on a tightly integrated server fleet where each server has a specific responsibility. Often, applications depend on multiple servers for completeness of functionality.

As shown in the following diagram, in a tightly coupled architecture, the web server fleet has a direct dependency on all application servers, and vice versa:

Figure 2.7: Tightly coupled architecture

In the preceding architecture diagram, if one application server goes down, then all web servers will start receiving errors, as the request will route to an unhealthy application server, which may cause a complete system failure. With tightly coupled architecture, if you want to scale by adding and removing servers, it requires lots of work, as all connections need to be set up appropriately.

With loose coupling, you can add an intermediate layer, such as a load balancer or a queue, which automatically handles failures or scaling for you.

In the previous section, you learned about loose coupling and how important it is for our architecture to be loosely coupled for scalability and fault tolerance. Developing service-oriented thinking will help to achieve a loosely coupled architecture (as opposed to server-oriented thinking, which can lead to hardware dependency and a tightly coupled architecture). Microservice-based event-driven architecture helps us to achieve ease of deployment and maintenance for our solution design.

In a RESTful architecture, you can format a message in XML, JSON, or plain text and send it over Internet using a simple HTTP protocol. RESTful architecture is popular as it is very lightweight. Microservices are based on RESTful architecture and are independently scalable, which makes it easier to expand or shrink one component of your application without impacting others.

As you can see in the following diagram, in a monolithic architecture, all components are built...

Any software solution revolves around the collection and management of data. Take the example of an e-commerce website; the software application is built to showcase product data on the website and encourage the customers to buy the products. It starts by collecting customer data when they create a login, adding a payment method, storing order transactions, and maintaining inventory data as the product gets sold. Another example is a banking application, which stores customer financial information and handles all financial transaction data with integrity and consistency. The most important thing for any application is handling, storing, and securing data appropriately. Data heavily influences solution design, and by keeping data in mind, you can apply the right design-driven solution for your needs.

It’s not just application design that revolves around data but operational maintenance and business decisions, too. You need to add monitoring capabilities...

Security is one of the essential aspects of solution design; any gap in security can have a devastating effect on a business or organization’s future. Many organizations are compromised by security breaches, resulting in a loss of customer trust and damaging businesses’ reputations. Industry-standard regulations, such as PCI (Payment Card Industry), HIPAA (Health Insurance Portability and Accountability Act), GDPR (General Data Protection Regulation), and SOC (System and Organization Controls) compliance are pivotal frameworks securing data across distinct domains. PCI secures credit card information in finance, HIPAA safeguards patient data in healthcare, GDPR enhances data privacy in the EU, and SOC ensures data management security in service organizations, enforce security safeguards to protect consumer data while providing standard guidance to the organization. Depending on your industry and region, you must comply with local legislation...

Ensuring applications are both usable and accessible is a critical aspect of design that impacts the user experience significantly. Usability refers to how easy and intuitive an application is for users to interact with, which involves a user-friendly interface, clear navigation, and efficient task-completion processes. Accessibility, on the other hand, ensures that applications are usable by people with various disabilities. Let’s learn more about these.

Achieving usability

You want your users to have a seamless experience browsing through the application. It should be so smooth that they don’t even notice how easily they can find things without any difficulties. You can do this by making your application highly usable.

Usability is how quickly the user can learn navigation logic when using your application for the first time. It’s about how quickly they can bounce back if they make a mistake and whether...

Businesses evolve as they grow; applications scale to handle an increased user base and add more features to stay ahead and attain a competitive edge. A solution design needs to be extendable and flexible enough to modify an existing feature or add new functionality.

To achieve solution extensibility, a solutions architect must use a loosely coupled architecture wherever possible. At a high level, creating a RESTful or queue-based architecture can help develop loosely coupled communication between different modules or across applications. You will learn more about the other kinds of architecture in Chapter 4, Solution Architecture Design Patterns. In this section, we will take a simple example to explain the concept of architectural flexibility.

To modularize their application, organizations often want to build a platform with a group of features and launch them as separate applications. This is only possible with...

Architectural interoperability and portability are crucial aspects of modern software architecture, ensuring that applications can work across different environments and interact seamlessly with other systems. Let’s look at these concepts.

Making applications interoperable

Interoperability is the ability of one application to work with others through a standard format or protocol. Often, an application must communicate with various upstream systems to consume data and downstream systems to supply data, so it is essential to establish that communication seamlessly.

An e-commerce application, for example, needs to work with other applications in the supply chain management ecosystem. This includes enterprise resource planning applications to record all transactions, transportation life cycle management, shipping companies, order management, warehouse management, and labor management.

All applications should...

Most accidents happen due to human error, which can be avoided using automation. Automation not only handles jobs efficiently but also increases productivity and saves costs. Anything identified as a repeatable task can be automated to free up valuable human resources so team members can spend their time on more exciting work and focus on solving a real problem. It also helps to increase team morale.

When designing a solution, think about what can be automated. Think about automating any repeatable task. Consider the following components to be automated in your solution:

• Application testing: You need to test your application every time you make any changes to ensure nothing breaks. Also, manual testing is very time-consuming and requires lots of resources. Automating repeatable test cases is better to speed up deployment and product launch. Automate your testing on a production scale and use rolling deployment techniques, such as canary...

There may be a situation when the entire region where your data center is located goes down due to massive power grid outages, earthquakes, floods, or a security attack but your global business should continue running. In such situations, you must have a disaster recovery plan in which you will plan your business continuity by preparing sufficient IT resources in an entirely different region, perhaps even in different continents or countries, so that your business can get back up and running quickly or experience no downtime at all.

When planning disaster recovery, a solutions architect must understand an organization’s Recovery Time Objective (RTO) and Recovery Point Objective (RPO). RTO measures how much downtime a business can sustain without significant impact; RPO indicates how much data loss a business can tolerate. Reducing RTO and RPO means incurring higher costs, so it is essential to understand whether the business is mission-critical...

Operational excellence can be a great differentiator for your application by providing a high-quality service to customers with minimal outages. Applying operational excellence proactively also helps support and engineering teams increase productivity. Maintainability goes hand in hand with operational excellence. Easily maintainable applications help reduce costs, avoid errors, and let you gain a competitive edge.

A solutions architect needs to design for operation, including how the workload will be deployed, updated, and operated in the long term. Planning for logging, monitoring, and alerting is essential to capture all incidents and take quick action for the best user experience. Apply automation wherever possible, whether deploying infrastructures or changing the application code, to avoid human error.

Including deployment methods and automation strategy in your design is very important, as this can accelerate the time to market for any new changes...

When designing an application architecture, the significant limitations are cost, time, budget, scope, schedule, and resources. Overcoming these constraints is a significant factor that must be considered while designing a solution. You should look at the limitations as challenges that can be overcome rather than obstacles, as challenges always push you to the limit of innovation.

A solutions architect needs to make suitable trade-offs while considering the constraints. For example, a high-performance application results in more cost when you need to add additional caching in multiple layers of architecture. However, sometimes, cost is more important than performance, primarily if a system is used by internal employees, which may not directly impact revenue. Sometimes, the market is more important than launching a fully featured product, and you need to make the trade-off between scope versus speed. In such scenarios, you can take the minimum...

In this chapter, you explored an in-depth overview of design principles required to architect effective and efficient systems. Initially, we delved into scalable architecture design, detailing predictive and reactive scaling strategies, and discussing techniques for scaling architecture, including strategies for static content, session management for application server scaling, and database scaling. We also looked at the importance of elasticity.

The chapter then explored constructing a highly available and resilient architecture, emphasizing the necessity of fault tolerance and using replaceable resources for robust system design. A separate section was dedicated to performance, underscoring how to build systems that perform optimally under various conditions.

The principle of loose coupling was discussed next, highlighting its importance in modern design, followed by the approach of “services, not servers,” which is central to the serverless computing...