dot-patterns

name	dot-patterns
description	Use when you need copy-paste DOT templates for common diagram types — start from a working pattern rather than blank canvas

DOT Pattern Templates

Overview

Ready-to-use DOT templates for the most common diagram types. Each template is complete, renders correctly, and demonstrates the right shape vocabulary and layout choices. Copy, rename nodes, adjust labels.

Core principle: Start from a working pattern. Blank canvas invites bad defaults. Templates encode proven shape vocabulary, layout direction, and structural choices.

Pattern Selection

How to choose the right template:

digraph pattern_selection {
    rankdir=TB
    node [shape=diamond style="rounded,filled" fillcolor="#FFF9C4" fontname="Helvetica"]
    edge [fontname="Helvetica" fontsize=10]

    Q1 [label="Has states\nwith transitions?"]
    Q2 [label="Hierarchical\nlayers/tiers?"]
    Q3 [label="Parallel\nbranches?"]
    Q4 [label="Step-by-step\nflow?"]

    node [shape=box style="rounded,filled" fillcolor="#E8F0FE"]
    SM   [label="State Machine"]
    LA   [label="Layered Architecture"]
    FOFI [label="Fan-Out / Fan-In"]
    DAG  [label="DAG / Workflow"]
    LEG  [label="Add a Legend"]

    Q1 -> SM   [label="yes"]
    Q1 -> Q2   [label="no"]
    Q2 -> LA   [label="yes"]
    Q2 -> Q3   [label="no"]
    Q3 -> FOFI [label="yes"]
    Q3 -> Q4   [label="no"]
    Q4 -> DAG

    node [shape=note style="filled" fillcolor="#F0F4C3"]
    NOTE [label="Using color?\nAdd a Legend"]
    DAG  -> NOTE [style=dashed]
    LA   -> NOTE [style=dashed]
}

---

Template 1: DAG / Workflow

Use for pipelines, CI/CD flows, processing steps, data pipelines.

digraph workflow {
    label="Workflow Title"
    labelloc=t
    rankdir=LR
    node [shape=box style="rounded,filled" fillcolor="#E8F0FE" fontname="Helvetica"]
    edge [fontname="Helvetica" fontsize=10 color="#666666"]

    Start  [label="Start" shape=ellipse fillcolor="#C8E6C9"]
    StepA  [label="Step A"]
    StepB  [label="Step B"]
    StepC  [label="Step C"]
    Done   [label="Done" shape=ellipse fillcolor="#FFCDD2"]

    Start -> StepA
    StepA -> StepB [label="on success"]
    StepA -> StepC [label="on failure" style=dashed color="#E57373"]
    StepB -> Done
    StepC -> Done
}

---

Template 2: State Machine

Use for lifecycle states, order status, connection states, document workflows.

digraph state_machine {
    label="State Machine Title"
    labelloc=t
    rankdir=LR
    node [shape=box style="rounded,filled" fillcolor="#E8F0FE" fontname="Helvetica"]
    edge [fontname="Helvetica" fontsize=10]

    // Initial state marker
    _start [shape=point width=0.2 fillcolor=black]

    // States
    Idle      [label="Idle"]
    Active    [label="Active"]
    Paused    [label="Paused"]
    Terminal  [label="Terminal" shape=doublecircle fillcolor="#FFCDD2"]

    // Transitions
    _start -> Idle
    Idle   -> Active  [label="start"]
    Active -> Paused  [label="pause"]
    Active -> Terminal [label="complete"]
    Paused -> Active  [label="resume"]
    Paused -> Terminal [label="cancel"]
}

---

Template 3: Layered Architecture

Use for system architecture, n-tier applications, domain boundaries.

digraph layered_arch {
    label="System Architecture"
    labelloc=t
    rankdir=TB
    compound=true
    node [fontname="Helvetica" style="rounded,filled"]
    edge [fontname="Helvetica" fontsize=10]

    subgraph cluster_presentation {
        label="Presentation Layer"
        style=filled fillcolor="#E3F2FD"
        node [fillcolor="#BBDEFB"]
        WebUI  [label="Web UI"]
        MobileUI [label="Mobile UI"]
    }

    subgraph cluster_api {
        label="API Layer"
        style=filled fillcolor="#E8F5E9"
        node [fillcolor="#C8E6C9"]
        Gateway [label="API Gateway"]
        Auth    [label="Auth Service"]
    }

    subgraph cluster_domain {
        label="Domain Layer"
        style=filled fillcolor="#FFF9C4"
        node [fillcolor="#FFF59D"]
        CoreSvc [label="Core Service"]
        Events  [label="Event Bus"]
    }

    subgraph cluster_data {
        label="Data Layer"
        style=filled fillcolor="#FCE4EC"
        node [fillcolor="#F8BBD9"]
        DB    [label="Database" shape=cylinder]
        Cache [label="Cache" shape=cylinder]
    }

    WebUI    -> Gateway [lhead=cluster_api]
    MobileUI -> Gateway [lhead=cluster_api]
    Gateway  -> CoreSvc [lhead=cluster_domain]
    Auth     -> CoreSvc [lhead=cluster_domain]
    CoreSvc  -> DB      [lhead=cluster_data]
    CoreSvc  -> Cache   [lhead=cluster_data]
}

---

Template 4: Fan-Out / Fan-In

Use for parallel processing, scatter-gather, map-reduce, worker pools.

digraph fan_out_fan_in {
    label="Parallel Processing"
    labelloc=t
    rankdir=LR
    node [shape=box style="rounded,filled" fillcolor="#E8F0FE" fontname="Helvetica"]
    edge [fontname="Helvetica" fontsize=10 color="#666666"]

    Input    [label="Input"]
    Dispatch [label="Dispatch" shape=component fillcolor="#C8E6C9"]

    subgraph { rank=same; WorkerA; WorkerB; WorkerC }
    WorkerA [label="Worker A"]
    WorkerB [label="Worker B"]
    WorkerC [label="Worker C"]

    Collect  [label="Collect" shape=component fillcolor="#FFCDD2"]
    Output   [label="Output"]

    Input    -> Dispatch
    Dispatch -> WorkerA
    Dispatch -> WorkerB
    Dispatch -> WorkerC
    WorkerA  -> Collect
    WorkerB  -> Collect
    WorkerC  -> Collect
    Collect  -> Output
}

---

Template 5: Legend

Add to any diagram that uses color or non-obvious shapes.

digraph with_legend {
    label="Diagram With Legend"
    labelloc=t
    rankdir=LR
    node [shape=box style="rounded,filled" fontname="Helvetica"]
    edge [fontname="Helvetica" fontsize=10]

    // Main diagram nodes
    SvcA [label="Service A" fillcolor="#E8F0FE"]
    SvcB [label="Service B" fillcolor="#E8F0FE"]
    DB   [label="Database"  shape=cylinder fillcolor="#FCE4EC"]
    Ext  [label="External"  shape=parallelogram fillcolor="#FFF9C4"]

    SvcA -> SvcB
    SvcB -> DB
    Ext  -> SvcA

    // Legend cluster
    subgraph cluster_legend {
        label="Legend"
        style=filled fillcolor="#F5F5F5"
        node [width=1.5]

        L_svc [label="Service"   shape=box         fillcolor="#E8F0FE"]
        L_db  [label="Data Store" shape=cylinder    fillcolor="#FCE4EC"]
        L_ext [label="External"  shape=parallelogram fillcolor="#FFF9C4"]

        L_svc -> L_db  [style=invis]
        L_db  -> L_ext [style=invis]
    }
}

---

Template Checklist

Before submitting a diagram created from a template:

• Title set via label= and labelloc=t on the graph
• All node IDs replaced with meaningful names
• All label= values updated to real content
• Shape vocabulary matches what the node actually is (service, store, decision, etc.)
• Color is consistent and a legend is included if color carries meaning
• Diagram renders without errors: dot -Tsvg diagram.dot > /dev/null