drawio-logical-diagrams

Draw.io Logical Diagrams Creation

Overview

Create professional logical diagrams in draw.io's native XML format. This skill enables generation of production-ready .drawio files for logical flow diagrams, system architecture visualizations, and abstract process representations using generic shapes and symbols.

When to Use

Use this skill when:

Creating logical flow diagrams showing data flow between system components
Designing logical architecture diagrams (abstract system structure)
Building BPMN process diagrams for business processes
Drawing UML diagrams (class, sequence, activity, state)
Creating data flow diagrams (DFD) for system analysis
Making decision flowcharts with branching logic
Visualizing system interactions and sequences
Documenting logical system design without cloud specifics

Do NOT use for:

AWS/Azure/GCP architecture diagrams (use aws-drawio-architecture-diagrams )
Infrastructure-specific diagrams

Instructions

Creating a Logical Diagram

Analyze the request: Understand the system/process to diagram
Choose diagram type: Flowchart, architecture, BPMN, UML, DFD, etc.
Identify elements: Determine actors, processes, data stores, connectors
Draft XML structure: Create the mxGraphModel with proper root cells
Add shapes: Create mxCell elements with appropriate styles
Add connectors: Link elements with edge elements
Validate XML: Ensure all tags are closed and IDs are unique
Output: Write the .drawio file for the user

Key XML Components

mxfile : Root element with host and version
diagram : Contains the diagram definition
mxGraphModel : Canvas settings (grid, page size)
root : Container for all cells (must include id="0" and id="1")
mxCell : Individual shapes (vertices) or connectors (edges)

Draw.io XML Structure

Every .drawio file follows this XML structure:

Key rules:

IDs "0" and "1" are reserved for root cells
Use sequential integer IDs starting from "2"
Use landscape orientation for architecture diagrams
All coordinates must be positive and aligned to grid (multiples of 10)

Generic Shapes and Styles

Basic Shape Types

Shape Style

Rectangle rounded=0;whiteSpace=wrap;html=1;

Rounded Rectangle rounded=1;whiteSpace=wrap;html=1;

Ellipse/Circle ellipse;whiteSpace=wrap;html=1;

Diamond rhombus;whiteSpace=wrap;html=1;

Cylinder shape=cylinder3;whiteSpace=wrap;html=1;boundedLbl=1;

Hexagon shape=hexagon;perimeter=hexagonPerimeter2;whiteSpace=wrap;html=1;

Parallelogram shape=ext;double=1;rounded=0;whiteSpace=wrap;html=1;

Standard Color Palette

Element Type Fill Color Border Color Usage

Process #dae8fc (light blue) #6c8ebf

Operations/actions

Decision #fff2cc (light yellow) #d6b656

Conditional branches

Start/End #d5e8d4 (light green) #82b366

Terminal states

Data/Store #e1f5fe (light cyan) #0277bd

Databases/files

Entity #f3e5f5 (light purple) #7b1fa2

External systems

Error/Stop #f8cecc (light red) #b85450

Error states

Actor/User #ffe0b2 (light orange) #f57c00

Users/actors

Container #f5f5f5 (light gray) #666666

Grouping areas

Connector Styles

Standard flow:

edgeStyle=orthogonalEdgeStyle;rounded=0;orthogonalLoop=1;jettySize=auto;html=1;endArrow=classic;endFill=1;strokeColor=#666666;strokeWidth=2;

Dashed (alternative/optional):

edgeStyle=orthogonalEdgeStyle;dashed=1;dashPattern=5 5;strokeColor=#666666;

Arrow head styles:

endArrow=classic;endFill=1
Filled triangle
endArrow=open;endFill=0
Open arrow
endArrow=blockThin;endFill=1
Block arrow

Diagram Types

Logical Flow Diagram

Shows the logical flow of data or processes through system components:

┌─────────┐ ┌─────────┐ ┌─────────┐ │ User │────▶│ Service │────▶│ Data │ └─────────┘ └─────────┘ └─────────┘

Key elements:

Actors/Users (orange)
Services/Processes (blue)
Data Stores (cyan)
External Systems (purple)
Data flows (solid arrows)

Logical Architecture Diagram

Abstract representation of system components:

┌─────────────────────────────────────────┐ │ Presentation Layer │ │ ┌─────────────┐ ┌─────────────┐ │ │ │ Web UI │ │ Mobile │ │ │ └─────────────┘ └─────────────┘ │ └─────────────────────────────────────────┘ │ ┌─────────────────────────────────────────┐ │ Application Layer │ │ ┌─────────────┐ ┌─────────────┐ │ │ │ API │ │ Business │ │ │ │ Gateway │ │ Logic │ │ │ └─────────────┘ └─────────────┘ │ └─────────────────────────────────────────┘ │ ┌─────────────────────────────────────────┐ │ Data Layer │ │ ┌─────────────┐ ┌─────────────┐ │ │ │ Database │ │ Cache │ │ │ └─────────────┘ └─────────────┘ │ └─────────────────────────────────────────┘

BPMN Process Diagram

Business process modeling:

Symbol Meaning

Circle Start/End Event

Rounded Rectangle Activity/Task

Diamond Gateway/Decision

Arrow Sequence Flow

UML Sequence Diagram

Interaction between components:

┌─────────┐ ┌─────────┐ ┌─────────┐ │ Actor │ │Service A│ │Service B│ └────┬────┘ └────┬────┘ └────┬────┘ │ │ │ │─────────────▶│ │ │ │─────────────▶│ │ │◀─────────────│ │◀─────────────│ │

Data Flow Diagram (DFD)

System data movement:

External Entity (square) - Sources/destinations
Process (circle/rounded) - Transformations
Data Store (open rectangle) - Storage
Data Flow (arrow) - Data movement

Shape Examples

Simple Process Box

Decision Diamond

Start/End Oval

Data Store (Cylinder)

Connector/Arrow

Label on Connector

Layout Best Practices

Flow direction: Left-to-right or top-to-bottom consistently
Spacing: 40-60px between elements, 20px inside containers
Grid alignment: All coordinates in multiples of 10
Label placement: Above horizontal arrows, right of vertical arrows
Container grouping: Use rounded rectangles for logical groupings
Balance: Keep diagrams centered, avoid extreme whitespace

Reference Files

For detailed templates and shape references, see:

shape-styles.md - Complete shape and style reference
diagram-templates.md - Ready-to-use templates

Examples

Example 1: Simple Order Processing Flow

User Request: "Create a logical flow diagram showing order processing: customer submits order, system validates, if valid then processes payment and ships, if invalid notifies customer."

Generated XML:

Example 2: Three-Tier Logical Architecture

User Request: "Create a logical architecture diagram for a web application with presentation, business logic, and data tiers."

Generated XML:

Example 3: Microservice Communication Flow

User Request: "Create a logical diagram showing microservice architecture with API gateway, multiple services, and message queue for async communication."

Reference: See diagram-templates.md for complete microservice template.

Constraints and Warnings

Critical Constraints

XML validity: Always close tags properly and escape special characters
Unique IDs: All cell IDs must be unique (except parent "0" and "1")
Valid references: Source/target must reference existing cell IDs
Positive coordinates: All x, y values must be >= 0

Warnings

XML files must be well-formed or will fail to open in draw.io
Invalid parent references cause elements to disappear
Negative coordinates place elements outside visible canvas

Best Practices

Visual Guidelines

Use consistent colors per element type
Keep arrows straight with minimal bends
Place labels at least 20px from arrow lines
Group related elements in containers
Use 12-14px font for labels, 10-11px for annotations

Accessibility

Use high contrast colors
Don't rely solely on color to convey meaning
Include text labels for all shapes
Add annotations for complex flows

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