How to Create Good Software Architecture Diagrams

10 min readAug 28, 2024

Software architecture diagrams are important tools for anyone involved in building software. They help us understand how different parts of a system work together. But sometimes, these diagrams can be confusing or too complicated, making it hard to get the main point.

Over the years, I’ve seen a lot of different architecture diagrams. Some were very detailed, while others were more basic. However, many of them had a problem — they didn’t clearly show what was most important about the system.

Common Problems with Software Diagrams

When I first started working in software development, I was exposed to a wide range of architecture diagrams. Some were overly complex, while others were too simplistic. Many diagrams suffered from common problems that made them difficult to understand. For example:

Mixing Levels of Detail:One big issue is when a diagram tries to show too much at once. For example, a diagram might start by showing the overall system but then suddenly dive into the small details. This can be confusing because it mixes different levels of detail. It’s important to keep things consistent so the diagram is easy to follow.
Inconsistent Use of Colors and Sizes:Another problem is using too many colors or sizes to represent different things. While colors can help highlight important parts, they can also make the diagram harder to read if not used carefully. Similarly, using different sizes for boxes or elements to show importance can be misleading, especially as the system changes over time.
Overly Complex Diagrams:Some diagrams try to include every possible detail about the system, making them overwhelming to look at. When a diagram is too complex, it becomes difficult to extract the most important information. Instead of clarifying the architecture, it can actually make it harder to understand.

I’ve made these mistakes too. I’ve used various tools like Whiteboard, MS Paint, Photoshop, draw.io , canva to create diagrams. No matter which tool you use, it’s easy to get caught up in making things look perfect instead of focusing on what really matters — clearly communicating the system’s structure.

Finding a Better Way

So, after making these mistakes , I found a better way to create clear and useful software architecture diagrams. This better way is called the C4 model.

while using the C4 model approach you also need a right tool for your architecture diagrams one of the best tool for creating these diagrams is cloudairy cloudchart

Using Cloudairy Cloudchart for Diagrams

While the C4 model helps organize your diagrams, you also need the right tools to create and update them. One of the best tools for this is Cloudairy Cloudchart.

How to Use Cloudairy Cloudchart for C4 Diagrams

Here’s how you can use Cloudairy Cloudchart to create diagrams using the C4 model:

Start with a Template: Cloudairy Cloudchart offers templates for different types of diagrams. Choose a template that matches the type of diagram you want to create.

2. Add Elements: Use Cloudairy Cloudchart drag-and-drop tools to add the elements you need, like users, systems, and relationships for a context diagram, or containers for a container diagram.

3. Customize Your Diagram: You can customize your diagram’s colors, labels, and shapes to make it clear and visually appealing.

4. Collaborate in Real-Time: Invite your team to work on the diagram with you. You can leave comments, suggest changes, and make sure everyone is on the same page.

5. Share Your Diagram: Once your diagram is ready, you can easily share it by embedding it in documents, presentations, or project management tools.

Why Use Cloudairy Cloudchart ?

Cloudairy Cloudchart is an online tool that makes it easy to create software architecture diagrams. Some of the features of Cloudairy Cloudchart :

Easy to Use: It has a simple drag-and-drop interface, so you can create diagrams quickly without spending a lot of time learning how to use the tool.
Collaboration Features: It lets multiple people work on a diagram at the same time. This is great for teams that need to brainstorm, design, and update their architecture together, especially if team members are in different locations.
Templates and Shapes: It has lots of templates and shapes to help you create different types of diagrams, including those needed for the C4 model.
Access from Anywhere: Since it is cloud-based, you can access your diagrams from anywhere, on any device. This is especially useful for remote teams.
Version Control: It tracks changes to your diagrams, so you can see how they’ve evolved over time and go back to earlier versions if needed.
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What is the C4 Model?

The C4 model is a method for creating software diagrams that break down a system into different levels of detail. This helps people understand the system from different perspectives without getting overwhelmed.

Here’s a simple explanation of the C4 model:

Context Diagrams (Level 1): These diagrams show the system as a whole and how it interacts with users and other systems. This is the big picture, helping everyone, even non-technical people, understand the system’s main purpose. Example: Imagine you’re working on an online banking system. A context diagram would show the banking system itself, the customers who use it, and other systems it interacts with, such as an email service or a mainframe banking system. This gives everyone a clear understanding of the system’s overall structure and its external connections.
Container Diagrams (Level 2): These diagrams zoom in a bit and show the main parts of the system, like web applications, databases, or services. This level helps technical people see how the system is structured. Example: In the online banking system, a container diagram might show the web application that customers use, the database that stores account information, and a payment service that handles transactions. This helps the team see how the system is organized and how the different parts fit together
Component Diagrams (Level 3): These diagrams break down each part of the system into smaller pieces, showing how these pieces work together. This level is useful for developers who need to understand how different parts of the system are connected. Example: Within the web application container of the online banking system, a component diagram might show different modules such as login, account management, and transaction processing. This helps developers understand the internal structure of the web application and how the components interact.
Code Diagrams (Level 4): These are the most detailed diagrams, showing the actual code structure or design. These diagrams are for developers who need to see how the code is organized. Example: A code diagram might show the classes and methods used in the transaction processing module of the online banking system. This helps developers see how the code is organized and how it supports the overall architecture.

The C4 model uses simple elements like boxes and lines to represent different parts of the system. It encourages clear labeling and a simple layout, making the diagrams easy to understand and collaborate on.

The C4 approach

C4 supports the idea of evolutionary architecture — where the architecture can change and grow as needed. The C4 model allows you to start with a simple diagram and add more details as the system evolves. This makes it perfect for teams that work in an agile way, where things are always changing.

For example, imagine you’re working on an online banking system. A Level 1 context diagram would show the whole system, including how it connects with users and other systems like email or mainframe systems. This gives everyone a clear understanding of the system’s overall structure.

At Level 2, you would create a container diagram that shows the main parts of the system, like the web application, database, and payment service. This helps the team see how the system is put together.

At Level 3, you would create a component diagram that breaks down each main part into smaller pieces, such as the different modules of the web application. This helps developers understand how everything fits together.

Finally, at Level 4, you would create code diagrams that show the details of the code, such as classes or database tables. This level helps developers see how the code is organized and how it supports the system.

Using PlantUML for Diagrams

While the C4 model helps you create clear diagrams, updating them as the system changes can still take a lot of time. This is where PlantUML comes in handy.

PlantUML is a tool that lets you create diagrams using plain text. Instead of using a drawing program, you can write your diagrams as code. This has several advantages:

Version Control: Because PlantUML diagrams are just text, you can save them in version control systems like GIT. This makes it easy to track changes and collaborate with others.
Collaboration: PlantUML’s text format makes it easy to share and edit diagrams with your team. You can review and update diagrams directly in the code.
Automation: You can automate the process of creating and updating diagrams by integrating PlantUML with your development pipeline. For example, you could set up a Jenkins job to generate the latest diagrams every time the code changes.
Integration: PlantUML works well with popular coding tools like Visual Studio Code and IntelliJ IDEA, so you can create and update diagrams without leaving your coding environment.

Here’s an example of how you might use PlantUML to create a Level 1 System Context diagram for an online banking system:

@startuml
!include C4_Context.pumlLAYOUT_WITH_LEGEND()title System Context diagram for E-commerce PlatformPerson(customer, "Online Shopper", "A customer who buys products through the e-commerce platform.")
Person(admin, "System Administrator", "Manages the platform and ensures its smooth operation.")
System(ecommerce_system, "E-commerce Platform", "Allows customers to browse products, place orders, and make payments.")System_Ext(payment_gateway, "Payment Gateway", "Processes online payments for orders.")
System_Ext(warehouse_system, "Warehouse Management System", "Manages inventory and shipping.")Rel(customer, ecommerce_system, "Browses and purchases products")
Rel(admin, ecommerce_system, "Administers and monitors the platform")
Rel(ecommerce_system, payment_gateway, "Processes payments")
Rel(ecommerce_system, warehouse_system, "Sends order and shipping details")
@enduml

In this example, the diagram represents an E-commerce Platform and its interactions with an online shopper, a system administrator, a payment gateway, and a warehouse management system. It shows the relationships between the different entities involved in the system

Other Diagrams and Tools

PlantUML also lets you create other types of diagrams, like System Landscape Diagrams, Dynamic Diagrams, and Deployment Diagrams. These additional diagrams can help you understand more complex parts of the system.

There are also plugins for tools like Visual Studio Code and IntelliJ IDEA that let you create and view diagrams right in your coding environment. If you prefer, you can even set up a local PlantUML server using Docker:

docker run -d -p 8080:8080 plantuml/plantuml-server:tomcat

This gives you more control and ensures that your diagrams aren’t dependent on external services.

Challenges with PlantUML

While PlantUML is a great tool, it does have some challenges. For example, positioning elements like arrows and boxes can be tricky, especially in complex diagrams. Unlike graphical tools where you can drag and drop, with PlantUML, you have to adjust the layout using code, which can take time.

Another drawback is that PlantUML requires a server component to generate diagrams, which might not be as convenient as some other tools that work directly in the browser. However, the benefits of version control, collaboration, and automation often outweigh these challenges.

Software architecture diagrams are powerful tools for understanding and communicating how a system works. But to be effective, these diagrams need to be clear, consistent, and easy to update. The C4 model provides a simple yet powerful way to create diagrams that meet these goals.

By using tools like PlantUML, you can make it easier to create, update, and share your diagrams, ensuring they stay useful as your system evolves. With the right approach and tools, you can create diagrams that help your team understand the system better and work more effectively.

So, may your diagrams be clear, easy to understand, and always up-to-date. With the cloudairy cloudchart and PlantUML, you’ll have everything you need to create great software architecture diagrams.

cloudairy cloudchart sign up link → https://chart.cloudairy.com/signup