BPMN Server

A Model Context Protocol (MCP) server that enables AI agents to create, manipulate, and manage BPMN 2.0 (Business Process Model and Notation) diagrams programmatically.

🎯 Overview

MCP-BPMN provides a standardized interface for AI assistants to work with business process diagrams. It generates valid BPMN 2.0 XML files that can be viewed and edited in any BPMN-compliant tool (VS Code BPMN Editor, Camunda Modeler, etc.).

Key Features

• ✅ Complete BPMN 2.0 Support: Events, activities, gateways, pools, and sequences
• ✅ Mermaid to BPMN Conversion: Bootstrap BPMN diagrams from Mermaid flowcharts
• ✅ Smart Auto-Layout: Automatic positioning with branch handling for gateways
• ✅ File Persistence: Save diagrams locally for editing in visual tools
• ✅ Proper Visual Rendering: Accurate waypoint calculation for connections
• ✅ Enterprise-Ready: Clean API design following BPMN standards
• ✅ No Browser Dependencies: Server-side XML generation

🚀 Quick Start

Installation

# Clone the repository
git clone https://github.com/your-org/mcp-bpmn.git
cd mcp-bpmn

# Install dependencies
npm install

# Build the project
npm run build

# Run tests (optional)
npm test

Configuration

For Claude Desktop

Add to your Claude Desktop configuration file:

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "mcp-bpmn": {
      "command": "node",
      "args": ["/absolute/path/to/mcp-bpmn/dist/server/index.js"]
    }
  }
}

For Other MCP Clients

Use the compiled CommonJS bundle:

node dist/server/bundle.cjs

📚 API Reference

Stateful Context Management

MCP-BPMN uses a stateful API design where you work with one diagram at a time. All operations apply to the current diagram context, eliminating the need for processId parameters.

Creation Tools

new_bpmn

Create a new BPMN process or collaboration diagram and set it as the current context.

{
  name: "Order Processing",
  type: "process" // or "collaboration" (optional, defaults to "process")
}

new_from_mermaid

Create a new BPMN diagram from Mermaid code and set it as the current context.

{
  name: "My Process",
  mermaidCode: "graph TD\n  A[Start] --> B[Task] --> C[End]"
}

File Operations

open_bpmn

Open an existing BPMN file and set it as the current context.

{
  filename: "my-process.bpmn"
}

open_mermaid_file

Open and convert a Mermaid file to BPMN, setting it as the current context.

{
  filename: "my-flowchart.mmd"
}

save

Save the current diagram to its file (requires filename to be set).

{}

save_as

Save the current diagram with a new filename.

{
  filename: "my-process.bpmn"
}

close

Close the current diagram and clear the context.

{}

current

Get information about the current diagram.

{}

Element Manipulation Tools

add_event

Add events (start, end, intermediate, boundary) to the current diagram.

{
  eventType: "start", // start, end, intermediate-throw, intermediate-catch, boundary
  name: "Order Received",
  eventDefinition: "message", // optional: message, timer, error, signal, etc.
  position: { x: 100, y: 200 } // optional
}

add_activity

Add activities (tasks, subprocesses) to the current diagram.

{
  activityType: "userTask", // task, userTask, serviceTask, scriptTask, etc.
  name: "Review Order",
  position: { x: 250, y: 200 }, // optional
  properties: { assignee: "reviewer" } // optional
}

add_gateway

Add gateways for branching logic to the current diagram.

{
  gatewayType: "exclusive", // exclusive, parallel, inclusive, eventBased
  name: "Payment Check",
  position: { x: 400, y: 200 } // optional
}

connect

Connect two elements with a sequence flow in the current diagram.

{
  sourceId: "StartEvent_1",
  targetId: "UserTask_1",
  label: "Start Flow", // optional
  condition: "amount > 1000" // optional, for conditional flows
}

add_pool

Add a pool (participant) to a collaboration diagram.

{
  name: "Customer",
  position: { x: 100, y: 100 }, // optional
  size: { width: 600, height: 250 } // optional
}

add_lane

Add a lane to a pool (not yet fully implemented).

{
  poolId: "Participant_1",
  name: "Sales Department",
  position: "bottom" // optional
}

Query and Manipulation Tools

list_elements

List all elements in the current diagram.

{
  elementType: "bpmn:Task" // optional filter
}

get_element

Get details of a specific element.

{
  elementId: "UserTask_1"
}

update_element

Update element properties.

{
  elementId: "UserTask_1",
  name: "Updated Task Name",
  properties: { assignee: "john.doe" }
}

delete_element

Delete an element and its connections.

{
  elementId: "Task_1"
}

Utility Tools

export

Export the current diagram as BPMN 2.0 XML.

{
  format: "xml", // only xml is currently supported
  formatted: true // optional, defaults to true
}

validate

Validate the current diagram structure.

{}

auto_layout

Apply automatic layout to position elements in the current diagram.

{
  algorithm: "horizontal" // currently only horizontal is supported
}

File Management Tools

list_diagrams

List all saved BPMN diagrams.

{}

delete_diagram_file

Delete a saved diagram file.

{
  filename: "old-process.bpmn"
}

get_diagrams_path

Get the storage path for diagrams.

{}

🔄 Context Management

The MCP-BPMN server uses a stateful design where you work with one diagram at a time:

1. Create or Open: Start by creating a new diagram (new_bpmn, new_from_mermaid) or opening an existing one (open_bpmn, open_mermaid_file)
2. Manipulate: All operations (add_event, connect, etc.) apply to the current diagram
3. Save: Save your work with save or save_as
4. Close: Close the current diagram with close

If you try to perform operations without a current context, you'll get a helpful error message:

No current context. Please create a diagram first with:
  - new_bpmn(name) to create a new BPMN diagram
  - new_from_mermaid(name, mermaidCode) to convert from Mermaid
  - open_bpmn(filename) to open an existing BPMN file
  - open_mermaid_file(filename) to convert a Mermaid file

💡 Examples

Example 1: Creating an Approval Process from Scratch

// Step 1: Create a new process (sets it as current context)
await new_bpmn({ name: "Approval Workflow" });

// Step 2: Add elements (all operations apply to current diagram)
await add_event({ eventType: "start", name: "Request Received" });
await add_activity({ activityType: "userTask", name: "Review Request" });
await add_gateway({ gatewayType: "exclusive", name: "Approved?" });
await add_activity({ activityType: "serviceTask", name: "Process Approval" });
await add_activity({ activityType: "userTask", name: "Handle Rejection" });
await add_event({ eventType: "end", name: "Complete" });

// Step 3: Connect elements
await connect({ sourceId: "StartEvent_1", targetId: "UserTask_1" });
await connect({ sourceId: "UserTask_1", targetId: "ExclusiveGateway_1" });
await connect({ sourceId: "ExclusiveGateway_1", targetId: "ServiceTask_1", label: "Yes" });
await connect({ sourceId: "ExclusiveGateway_1", targetId: "UserTask_2", label: "No" });
await connect({ sourceId: "ServiceTask_1", targetId: "EndEvent_1" });
await connect({ sourceId: "UserTask_2", targetId: "EndEvent_1" });

// Step 4: Apply auto-layout for proper positioning
await auto_layout();

// Step 5: Save and export the diagram
await save_as({ filename: "approval-workflow.bpmn" });
const xml = await export();

Example 2: Bootstrap from Mermaid (Recommended for Lower Token Usage)

// Step 1: Create from Mermaid syntax (much more concise!)
await new_from_mermaid({ 
  name: "Approval Workflow",
  mermaidCode: `
    graph TD
      A((Request Received)) --> B[Review Request]
      B --> C{Approved?}
      C -->|Yes| D[Process Approval]
      C -->|No| E[Handle Rejection]
      D --> F((Complete))
      E --> F
  `
});

// Step 2: Apply auto-layout (Mermaid conversion includes basic layout)
await auto_layout();

// Step 3: Make additional edits if needed
await update_element({ 
  elementId: "UserTask_1", 
  properties: { assignee: "reviewer" }
});

// Step 4: Save and export
await save_as({ filename: "approval-workflow.bpmn" });
const xml = await export();

Example 3: Working with Multiple Diagrams

// Create first diagram
await new_bpmn({ name: "Process A" });
await add_event({ eventType: "start" });
await add_activity({ activityType: "task", name: "Task A" });
await save_as({ filename: "process-a.bpmn" });

// Create second diagram (automatically closes the first)
await new_bpmn({ name: "Process B" });
await add_event({ eventType: "start" });
await add_activity({ activityType: "task", name: "Task B" });
await save_as({ filename: "process-b.bpmn" });

// Go back to first diagram
await open_bpmn({ filename: "process-a.bpmn" });
await add_event({ eventType: "end" });
await save();

// Check current diagram info
const info = await current();
console.log(info); // Shows: { name: "Process A", filename: "process-a.bpmn", ... }

🗂️ File Storage

BPMN diagrams are automatically saved to your local filesystem:

• Unix/Linux/Mac: ~/mcp-bpmn/
• Windows: %USERPROFILE%\mcp-bpmn\

Custom path via environment variable:

export MCP_BPMN_DIAGRAMS_PATH=/custom/path

Files are named: {ProcessId}_{ProcessName}.bpmn

🏗️ Architecture

Technology Stack

• TypeScript - Type-safe development
• Node.js - Runtime environment
• MCP SDK - Model Context Protocol implementation
• Jest - Testing framework

Key Components

• SimpleBpmnEngine - Core BPMN XML generation without browser dependencies
• DiagramContext - Stateful context management for current diagram
• AutoLayout - Smart positioning algorithm with branch handling
• BpmnRequestHandler - MCP request processing
• MermaidConverter - Mermaid to BPMN conversion
• TypeMappings - BPMN element type conversions
• IdGenerator - Consistent ID generation

Project Structure

mcp-bpmn/
├── src/
│   ├── core/           # Core BPMN engine
│   ├── server/         # MCP server implementation
│   ├── utils/          # Utilities (layout, ID generation)
│   ├── types/          # TypeScript type definitions
│   └── config/         # Configuration
├── tests/
│   ├── unit/          # Unit tests
│   ├── integration/   # Integration tests
│   └── e2e/           # End-to-end tests
├── dist/              # Compiled output
└── docs/              # Documentation

🧪 Development

Available Scripts

npm run build        # Build TypeScript
npm run build:bundle # Build CommonJS bundle
npm run build:watch  # Build with watch mode
npm test            # Run all tests
npm run test:unit   # Run unit tests only
npm run test:e2e    # Run end-to-end tests
npm run lint        # Run ESLint
npm run dev         # Development mode with hot reload
npm start           # Start the MCP server

Testing

The project includes comprehensive test coverage:

• Unit Tests: Core functionality testing
• Integration Tests: Handler and tool testing
• E2E Tests: Full MCP protocol testing

Run tests with:

npm test                    # All tests
npm run test:coverage       # With coverage report
npm run test:watch         # Watch mode

📈 Performance

• Fast XML Generation: Direct XML string building
• Efficient Layout: O(n) complexity for standard flows
• Minimal Dependencies: No browser or heavy libraries
• Bundled Size: ~48KB CommonJS bundle

🐛 Known Limitations

• SVG export not yet implemented (XML only)
• Vertical layout algorithm pending
• Lanes within pools not fully implemented
• Complex gateway merging patterns need manual positioning

🚧 Roadmap

• SVG export support
• Vertical and radial layout algorithms
• Enhanced BPMN validation framework
• Mermaid diagram import/export (Completed!)
• Natural language to BPMN conversion
• Integration with Camunda/Activiti engines
• Subprocess expansion support
• Message flow between pools
• BPMN execution simulation

🤝 Contributing

Contributions are welcome! Please:

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

Code Style

• TypeScript with strict mode
• ESLint configuration provided
• Jest for testing
• Conventional commits

📝 License

MIT License - see LICENSE file for details.

📞 Support

• Issues: GitHub Issues
• Discussions: GitHub Discussions
• Documentation: See /docs folder for detailed guides

🙏 Acknowledgments

• Built on the Model Context Protocol specification
• Inspired by bpmn-js for BPMN standards
• Thanks to the Anthropic team for MCP development