Diagram and Code Hybrid

In the forever complex world of software development, diagrams serve as vital tools for visualization, planning, and communication.
However, the traditional approach to diagram creation often results in static images that are difficult to update and maintain alongside dynamic codebases. Addressing this challenge, an innovative hybrid method utilizing PlantUML (PUML) for complex state diagrams and Graphviz for simpler illustrative diagrams emerges, is an efficient and long-term solution.

The Challenge: Keeping Diagrams Alive

Creating diagrams with traditional graphical tools frequently leads to a set of static images that quickly become outdated as project requirements evolve. This discrepancy between the static nature of diagrams and the dynamic development of code can lead to confusion, inefficiency, and a disconnect between documentation and implementation.

The Hybrid Solution: PUML and Graphviz

By combining the strengths of PUML and Graphviz, this hybrid approach offers a versatile solution for diagram management. PUML shines in its ability to describe complex state diagrams through concise, textual definitions, making it ideal for detailed documentation of software architecture and workflows. Graphviz, on the other hand, excels in generating simpler, more straightforward diagrams, such as dependency graphs or straightforward flowcharts, from DOT language descriptions.

How It Works

In this system, .puml files are used for comprehensive state diagrams requiring detailed representation, while .dot files cater to simpler, illustrative diagrams. Both types of files are stored under assets/, akin to source code. Upon modification, these textual descriptions are automatically converted into PNG images under assets/generated/, marrying the editability of code with the visual clarity of diagrams.

The Benefits Realized

Adopting this methodological hybrid offers several compelling advantages:

  • Versatility: By using PUML for complex diagrams and Graphviz for simpler ones, developers can choose the most appropriate tool for their needs, ensuring both clarity and detail where necessary.
  • Version Control: Treating diagrams as code enables the use of standard version control systems, facilitating tracking, review, and collaborative editing.
  • Maintainability: The ease of updating text files ensures that diagrams can swiftly evolve alongside the project, reducing the risk of documentation becoming obsolete.

Practical Example: Documenting a Microservices Architecture

Consider the task of documenting a microservices architecture. For the overarching architecture diagram showcasing service interactions, you might opt for a .dot file with Graphviz, capturing the simplicity and high-level view:

digraph G {
  Client -> Server;
  Server -> Database;

For a detailed state diagram of a specific service’s workflow, a .puml file would be more appropriate, allowing for an in-depth depiction of states and transitions:

[*] --> NotAuthenticated
NotAuthenticated --> Authenticated : Successful Login
Authenticated --> [*] : Logout
Authenticated --> Authenticated : Refresh Token

This approach not only facilitates the clear documentation of both high-level structures and detailed workflows but also integrates seamlessly into development workflows, ensuring diagrams remain relevant and accurate.


The innovative hybrid use of PUML for complex state diagrams and Graphviz for simpler illustrative visuals presents a forward-thinking solution to the perennial challenge of maintaining accurate, up-to-date documentation in software projects. By treating diagrams as code, this methodology leverages the strengths of both tools to ensure documentation is as dynamic and adaptable as the code it describes, bridging the gap between visual representation and code-based development.