Web Application Architecture: The Basics

“If you think good architecture is expensive, try bad architecture”.  Brian Foote and Joseph Yoder

Generally speaking, web application architecture is needed to create scalable, safe, hack-resistant, and easy-to-maintain systems. Just ask any seasoned developer about its importance, and you will get the immediate answer that the right choice of web app architecture is a long-term investment in the development of any project. Below, we will reveal the main aspects of web architecture, consider its key components and types, and explain how to architect a web application by providing some best practices adopted by our team.  

Defining Web Architecture

“Web application architecture” refers to its structure, which defines the connections between its components (such as the client and server parts, API, databases, networks, and other systems that power the application) and the rules for their interaction.

Today, no web development project begins without defining the architecture first – this is necessary to:

• Simplify the subsequent development of the project and its support (without architecture, the code will be chaotically placed in folders, and it will be difficult for developers to understand it);
• Maximize the performance of the web application;
• Provide the ability to scale and add new functions;
• Minimize the number of vulnerabilities (with well-structured code, implementing security measures is much easier and faster);
• Ensure fault tolerance (in unstructured applications, one error can lead to a system shutdown due to a lack of insulation between components).

Therefore, in the long term, a correctly chosen architecture ensures user loyalty due to the absence of delays and freezes and maximizes the software's life cycle.

Elements of Web Application Architecture

Now, let’s check the main elements of web app architecture.

Domain Name System (DNS)

DNS is designed to help a web browser find the right web address by domain name. In particular, it converts domain names into IP addresses of the servers where the application is located. DNS allows users to enter easy-to-remember names instead of complex IP addresses. This system also provides load balancing, speeds up query processing through caching, and redirects traffic to a backup server if the main server is unavailable.

Load Balancer

A load balancer distributes and encrypts incoming traffic using unique algorithms (such as Round Robin/Least Connections/Weighted Distribution) between several servers, ensuring uniform resource usage and high availability. Some balancers also perform health checks for servers and automatically redirect traffic when a central server fails. There are hardware, software, and cloud balancers—the choice of the type depends on the requirements of a specific project.

Web Application Servers

Web application servers are used to process user HTTP requests and implement business logic (in particular, through interpreting server-side languages, making requests, and processing records from databases).

Databases

Databases store structured or unstructured data, depending on their purpose. There are relational (SQL) ones, which have tables and support complex queries, and non-relational (NoSQL) ones, which store data in the form of documents, graphs, or key-value pairs.

Caching Services

Caching speeds up query execution by storing frequently used information in memory and reduces the workload on the database. There is an HTTP cache, which stores HTML pages and API responses, and an object cache, which stores the results of calculations or database queries.

Job Queues (Optional)

Job queues perform background operations that do not require an immediate response, such as sending emails, processing images, generating analytical reports, etc.

Full-Text Search Services (Optional)

Full-text search services index large volumes of text and speed up the search for them. They can also handle complex search queries.

Content Delivery Network (CDN)

A CDN is a distributed server network that caches and delivers content to users from nearby servers. Using a CDN will help you reduce delays in providing content to end users due to geographic proximity, ensure traffic scaling during peak loads, and minimize the likelihood of DDoS attacks.

Understanding 3-Tier Architecture

A three-tier web application infrastructure is a popular model in which an application is divided into three logical tiers: Presentation, Application, and Data.

Three-tier architecture is often chosen due to its versatility, flexibility, security, and ability to speed up the development and further support of the application since changes in one tier do not affect the others (because they are isolated from each other).

Layers in Modern Web Application Architecture

In this section, we propose to discuss each level of the three-tier web application structure in more detail.

Presentation/Client Layer

This layer contains everything that involves direct interaction with the end user. In particular, it includes the user interface, including forms for user input, buttons, and data received from the Business/Application layer.

Business/Application Layer

This layer is responsible for processing business logic and data management while accepting requests from the Presentation tier, processing them (e.g., validation, transactions, calculations, etc.), and returning results.

Data Access Layer

This layer is responsible for storing, collecting, and updating data using SQL or NoSQL databases and making data available through API or ORM (Object-Relational Mapping).

Types of Web Application Architectures

It's time to check the most popular  web app architecture diagrams.

Client-Side Architectures

As we can understand from the name, these architectures involve frequent interaction between the end user and the interface.

Single-Page Applications (SPAs)

Single-page applications are created considering that the central part of business logic and data presentation will be performed on the client side. This approach minimizes the load on the server by reducing server requests since the page content is loaded only once (subsequent changes are performed on the user side, dynamically, due to the History API or hash routing). As a result, users can comfortably interact with the app without delay, even with an interrupted or absent Internet connection (subject to pre-caching of data).

Progressive Web Apps (PWAs)

Progressive web apps can boast some advantages of native mobile applications, as they can be installed on user devices as second ones. Their development involves using a predefined set of technologies such as Service Workers (for offline operation), push notifications, caching, WebAssembly, etc. Thus, you get a single code for the web and mobile devices and can guarantee high performance to end users with a slow Internet connection.

Server-Side Architectures

Application server architectures are aimed at ensuring increased fault tolerance and software scalability.

Microservices Architecture

Typically, this is an enterprise web application architecture since it involves dividing the application into a set of independent services, each responsible for a specific business task and interacting with others via API. This approach ensures easy scaling of the software and its updating (because adding new functionality or upgrading an existing one takes minimal time). On the other hand, the initial creation of such an architecture can be resource-intensive (especially when implementing data synchronization mechanisms); moreover, not all projects can be divided into microservices.

Hosting Strategies

As its name suggests, this type of modern web app architecture pays special attention to where and how the web application is hosted.

Serverless Architecture

This web application architecture example enables running code without managing physical or virtual servers. At the same time, resource allocation, scaling, and support are on the side of the cloud provider. According to the serverless approach, the program code is launched only in response to specific events (like HTTP requests, data changes, or queued tasks), which means that the consumption of computing resources (from the cloud provider) occurs only during the actual use of the application.

Advanced and Scalable Web Application Architectures

In this section, we offer you the opportunity to consider several advanced and scalable types of web design architecture.

Data Storage Solutions

Such solutions provide the ability to choose the technology for specific tasks and guarantee increased availability and scalability of the web application. On the other hand, the wrong choice of database can lead to decreased performance.

Possible types of data storage solutions include:

• Relational databases (RDBMS) use a tabular data model based on SQL and are specially adapted for systems with clearly structured data and complex queries. These include MySQL, PostgreSQL, and Microsoft SQL Server;
• Non-relational databases (NoSQL) do not use a rigid data schema and are suitable for apps with large amounts of data that require horizontal scaling. Examples of NoSQL databases include MongoDB and Cassandra.
• Data warehouses are optimized for analytics and the processing of large data volumes. Typical examples are Amazon Redshift and Google BigQuery;
• Cloud solutions that provide data storage in the cloud and are characterized by automatic scaling. The most well-known examples are AWS S3 and Google Cloud Storage.

Load Balancing Solutions

Load balancing solutions distribute incoming user requests across multiple servers. Ultimately, this maximizes a web application's performance and ensures its stable and fault-tolerant operation under different load levels.

Possible types of load-balancing solutions:

• Hardware, such as F5 Big-IP and Cisco ACE – connect to the servers on which the web application is hosted;
• Software (such as HAProxy, NGINX, and Traefik), which are installed on the servers;
• Cloud services (such as AWS and Google Cloud) provided by cloud vendors are infinitely scalable and can be integrated with other cloud solutions.

Caching and Content Delivery Solutions

Caching and content delivery solutions accelerate web application performance by pre-saving frequently used data and reducing the distance required for its transmission (in particular, CDN delivers static content from the node geographically closest to the user). However, they can also complicate the architecture itself and tasks related to data synchronization.

Typical caching solutions:

• Local (browser HTTP caching), when data is stored on the user's device or server;
• Server, when data is stored on dedicated caching servers;
• Database caching (for example, in-memory cache) is aimed at speeding up reading frequently requested data.

Typical CDN solutions:

• Cloudflare;
• Akamai;
• AWS CloudFront.

Best Practices for Web Application Architecture

Finally, let's look at some web application architecture best practices.

Consider scalability and performance requirements

Since your web application will likely experience increasing user loads over time (as the number of concurrent users grows), it is essential to plan ahead for its ability to instantly respond to user actions. To ensure this, you need to think about how to split the application into functional modules, predispose the application to horizontal scaling (by adding servers), and integrate a load balancer to distribute user requests evenly.

Make the architecture secure

Web applications are often subject to network attacks such as SQL injections, XSS, CSRF, and DDoS, so your architecture must be compelling enough to counter them and minimize risks to end users successfully. In particular, you will need to implement authentication/authorization mechanisms, ensure data encryption at rest and in transit, and implement a web application firewall and other tools to detect threats and prevent data abuse by external systems.

Implement DevOps practices

DevOps practices aim to accelerate project development, testing, and deployment and usually consist of CI/CD automation, containerization (to quickly deploy applications regardless of the environment), and the implementation of the IaC approach.

Ensure ease of use of data

Since the more efficient the data processing process is organized, the faster the application and the better the user experience, you will need to carefully select the databases (usually relational ones are used for transactional operations, and NoSQL ones – for large volumes of unstructured data), introduce caching to reduce the load on them, and implement backup/replication mechanisms.

Develop with user experience in mind

The convenience and speed of modern web application are crucial in winning the loyalty of end users. Therefore, it is important to use client-side rendering for dynamic interfaces, implement CDN to speed up loading, introduce adaptive design to ensure compatibility with devices with different form factors, and minimize the number of server requests by consolidating resources.

Conclusion

We hope you have realized the importance of the well-thought-out creation of web application architecture and now understand the necessity of this stage in the development process. Please get in touch with us if you would like to delegate this and any other tasks related to your project's planning and implementation.