C4 Model and Mermaid

Using the excellent C4 model to create diagrams in mermaid.

All the templates have been prepared and tested with Mermaid Live Editor.

Level 1: Context

graph LR
    %% C4 style classes c4model.com %%
    classDef person fill:#08427b,stroke:#000,color:#FFF;
    classDef software fill:#1168bd,stroke:#000,color:#FFF;
    classDef existing fill:#999999,stroke:#000,color:#FFF;
    classDef boundary fill:#FFF,stroke:#000,stroke-width:2px,stroke-dasharray: 5 5;
    classDef frame fill:#FFF,stroke:#000

    %% nodes %%
    Person((Person)):::person
    SoftwareSystem:::software
    ExistingSystem["Software System,<br>Existing System"]:::existing

    %% connections and boundaries %%
    
    subgraph Legend
        Person-.->|Relationship| SoftwareSystem
        subgraph Boundary
            SoftwareSystem-.->|Relationship| ExistingSystem
        end
        class Boundary boundary
    end
    class Legend frame

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Level 2: Container

Note: app and browser are containers too

graph LR
    %% C4 style classes c4model.com %%
    classDef person fill:#08427b,stroke:#000,color:#FFF;
    classDef container fill:#1168bd,stroke:#000,color:#FFF;
    classDef database fill:#1168bd,stroke:#000,color:#FFF;
    classDef existing fill:#999999,stroke:#000,color:#FFF;
    classDef boundary fill:#FFF,stroke:#000,stroke-width:2px,stroke-dasharray: 5 5;
    classDef frame fill:#FFF,stroke:#000

    %% nodes %%
    Person((Person)):::person
    SoftwareSystem:::container
    ExistingSystem["Software System,<br>Existing System"]:::existing
    Database[(Database)]:::database

    %% connections and boundaries %%
    
    subgraph Legend
        Person-.->|Relationship| SoftwareSystem
        subgraph Boundary["Boundary: System under development"]
            SoftwareSystem-.->|Relationship| Database
        end
        class Boundary boundary
        SoftwareSystem-.->|Relationship| ExistingSystem
    end
    class Legend frame

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Level 3: Component

graph LR
    %% C4 style classes c4model.com %%
    classDef container fill:#1168bd,stroke:#000,color:#FFF;
    classDef component fill:#7ebced,stroke:#000,color:#FFF;
    classDef database fill:#1168bd,stroke:#000,color:#FFF;
    classDef existing fill:#999999,stroke:#000,color:#FFF;
    classDef boundary fill:#FFF,stroke:#000,stroke-width:2px,stroke-dasharray: 5 5;
    classDef frame fill:#FFF,stroke:#000

    %% nodes %%
    Container["Other Container"]:::container
    Component:::component
    ExistingSystem["Software System,<br>Existing System"]:::existing
    Database[(Database)]:::database

    %% connections and boundaries %%
    
    subgraph Legend
        Container-.->|Relationship| Component
        subgraph Boundary["Boundary: Container"]
            Component
        end
        Component-.->|Relationship| ExistingSystem
        Component-.->Database
        class Boundary boundary
    end
    class Legend frame

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