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  • Nithin Janardhanan

Untangling Complex IT Architectural Problems: How the C4 Architecture Model Saved My Project

As an experienced IT architect, I have dealt with my fair share of complex system designs. However, one project in particular stands out to me as a significant challenge. During the Covid-19 pandemic, I joined a project that was already in progress, but the initial team had left without giving any knowledge transfer. Upon looking into the documentation and diagrams, I found the project to be very complex. The architecture was vendor-specific, with manual CSV inputs and a lot of complex components. To make things worse, I was tasked to write the high-level design from this document in just two weeks! In this article, I want to share with you how I was able to overcome this challenge using the C4 architecture model.

Context Diagram: Understanding the Big Picture with the C4 Model

The C4 model helped me to take a step back and understand the big picture. I started by creating a context diagram that helped me to visualize the entire system and its interactions with external entities. I met with the business analyst and program manager to understand the exact vision and who interacts with the system. The context diagram gave me a clear understanding of the system's scope, boundaries, and external interfaces.

This approach streamlined the process and enabled me to initiate discussions with the product manager and business stakeholders.

Containers: Breaking Down the Architecture

Using the context diagram, I created a high-level view of the system's containers. The containers represented the high-level technology choices, such as databases, servers, and APIs, that the system was composed of. For each container, I created an input and output map that helped me to understand how data was flowing in and out of each container. By breaking down the architecture into containers, I was able to focus on the important technology choices that affected the system's functionality.

To ensure accuracy, I discussed the details with our segment architect and technology provider. Although it may appear simple, a significant amount of research and discussion went into this phase.

Components: Deriving a Microservice-based Architecture

I broke down each container into components, deriving a simple microservice-based scalable application architecture. This helped me to untangle the complex vendor-specific architecture and create a more adaptable and scalable solution. I used the C4 model to identify the main components of the system, their interactions, and their relationships to one another. For each component, I created a sequence diagram that helped me to understand the flow of data between the components.

Since the project was agile, not all containers were worked on at the same time. The C4 model helped us prioritize the work based on dependencies and requirements, ensuring that we were always working on the most critical components first. The entire exercise also gave us an estimated time to complete the project, which helped us plan better and meet our deadlines.

Input and Output Maps: Understanding Data Flow

For each container, I created an input and output map that helped me to understand how data was flowing in and out of each container. This helped me to identify the key data elements that were flowing between the containers and ensure that the system was designed to handle these data flows. By understanding the data flow, I was able to design a scalable and adaptable system that could handle the complex data requirements.

Building a Proof of Concept

Since this was a huge change, the team had doubts about it. They had worked for months to come up with the previous architecture, and my proposed solution was completely different. However, I quickly built a single item POC and showed it to everyone, and also prepared a mock UX that showed the entire process. This helped me to win over the team and get their buy-in for my proposed solution.


At the end, we designed an automated vendor-agnostic enterprise-level IoT device management solution. The C4 model was my boon for the entire process, helping me to see the big picture, untangle the complexity, and create a better solution. As an IT architect, it's important to have critical thinking skills and the ability to see the big picture. The C4 model is a powerful tool that can help any IT architect to untangle complex architectural problems and create scalable and adaptable solutions. In conclusion, the C4 architecture model helped me to overcome a challenging project during a difficult time.

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