drawio-logical-diagrams

Draw.io Logical Diagrams Creation

Overview

Create professional logical diagrams in draw.io's native XML format for logical flow diagrams, system architecture visualizations, and abstract process representations using generic shapes and symbols.

When to Use

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).

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: Verify XML is well-formed and all IDs are unique (see validation checklist below)
Output: Write the .drawio file for the user

XML Validation Checklist

Before outputting the file, verify:

All tags are properly closed (no unclosed <mxCell>, </mxGeometry>, etc.)
All cell IDs are unique (0 and 1 are reserved root cells, use sequential integers starting from 2)
All source and target attributes reference existing cell IDs
All parent attributes reference existing cell IDs
All coordinates (x, y, width, height) are positive numbers
Special characters are escaped (< → <, > → >, & → &)
Multi-line labels use 
 or <br> with html=1 in style

Key XML Components

Component	Description
`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

<mxfile host="app.diagrams.net" agent="Claude" version="24.7.17">

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`	`#6c8ebf`	Operations/actions
Decision	`#fff2cc`	`#d6b656`	Conditional branches
Start/End	`#d5e8d4`	`#82b366`	Terminal states
Data/Store	`#e1f5fe`	`#0277bd`	Databases/files
Entity	`#f3e5f5`	`#7b1fa2`	External systems
Error/Stop	`#f8cecc`	`#b85450`	Error states
Actor/User	`#ffe0b2`	`#f57c00`	Users/actors
Container	`#f5f5f5`	`#666666`	Grouping areas

Connector Styles

Standard flow:

Dashed (alternative/optional):

Arrow head styles:

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

Diagram Types

Type	Key Elements
Logical Flow	Actors (orange), Services (blue), Data Stores (cyan), External Systems (purple)
Logical Architecture	Layered containers with nested components
BPMN	Circle (Start/End), Rounded Rectangle (Activity), Diamond (Gateway)
UML Sequence	Vertical lifelines with message arrows
DFD	Square (Entity), Circle (Process), Open Rectangle (Data Store)

Reference Files

For detailed shape examples and style references, see:

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

Examples

Example 1: Order Processing Flow

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."

Example 2: Three-Tier Logical Architecture

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

For additional templates (microservice architecture, event-driven, decision tree, sequence, DFD), see diagram-templates.md.

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

Use consistent colors per element type across all diagrams
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
Align all coordinates to grid (multiples of 10)
Use high contrast colors and don't rely solely on color for meaning