# Workflow Engine API

Overview

A configurable state machine-based workflow engine built with .NET Core Web API. Enables defining, managing, and executing workflow instances with state transition validation and history tracking.

Key Features

• Define custom workflows with states and actions
• Start and manage workflow instances
• Execute state transitions with validation
• Track complete workflow history
• RESTful API with Swagger documentation

Quick Start

Prerequisites

• .NET 8.0 SDK
• Visual Studio 2022 or VS Code

Running the Application

# Clone and run
git clone https://github.com/Chimankarparag/Infonetica_Task.git
cd WorkflowEngine
dotnet restore
dotnet build
dotnet run

Access the application:

• API: http://localhost:5217
• Swagger UI: http://localhost:5217/swagger

API Endpoints

Workflow Definitions

Method	Endpoint	Description
GET	/api/WorkflowDefinition	List all definitions
GET	/api/WorkflowDefinition/{id}	Get definition by ID
POST	/api/WorkflowDefinition	Create definition

Workflow Instances

Method	Endpoint	Description
GET	/api/WorkflowInstance	List all instances
GET	/api/WorkflowInstance/{id}	Get instance by ID
POST	/api/WorkflowInstance/start/{definitionId}	Start instance
POST	/api/WorkflowInstance/{id}/execute	Execute action

Execute Workflow Actions

# Start instance
curl -X POST http://localhost:5217/api/WorkflowInstance/start/{definitionId}

# Execute action
curl -X POST http://localhost:5217/api/WorkflowInstance/{instanceId}/execute \
-H "Content-Type: application/json" \
-d '{"actionId": "submit"}'

Project Structure

WorkflowEngine/
├── Controllers/
├── Models/
├── Services/
└── Storage/

Technical Details

Implementation

• .NET 8.0 and ASP.NET Core Web API
• In-memory storage
• RESTful API with JSON payloads
• Swagger/OpenAPI documentation

Assumptions

• Single-user system (no auth)
• In-memory data storage
• Unique IDs within workflows
• Linear workflow progression

Limitations

• No persistent storage
• No concurrent execution handling
• No workflow versioning
• Basic validation only
• No conditional transitions
• No automatic transitions/timeouts

Validation Features

• Workflow definition validation
• State transition validation
• Action execution validation
• History tracking of all transitions

Example and Test API

1. Create a Workflow Definition

Endpoint: POST /api/WorkflowDefinition

Request Body:

{
  "name": "Document Approval",
  "states": [
    {
      "id": "draft",
      "name": "Draft",
      "isInitial": true,
      "isFinal": false,
      "enabled": true,
      "description": "Initial draft stage"
    },
    {
      "id": "review",
      "name": "Review",
      "isInitial": false,
      "isFinal": false,
      "enabled": true,
      "description": "Under review"
    },
    {
      "id": "approved",
      "name": "Approved",
      "isInitial": false,
      "isFinal": true,
      "enabled": true,
      "description": "Final approved state"
    }
  ],
  "actions": [
    {
      "id": "submit",
      "name": "Submit for Review",
      "enabled": true,
      "fromStates": ["draft"],
      "toState": "review",
      "description": "Submit document for review"
    },
    {
      "id": "approve",
      "name": "Approve Document",
      "enabled": true,
      "fromStates": ["review"],
      "toState": "approved",
      "description": "Approve the document"
    }
  ]
}

Expected Response:

Status: 201 Created

Response contains a valid definitionId

2. Start a Workflow Instance

Endpoint: POST /api/WorkflowInstance/start/{definitionId}

Use the definitionId returned from step 1.

Expected Response:

Status: 201 Created

Response contains an instanceId

3. Get Workflow Instance by ID

Endpoint: GET /api/WorkflowInstance/{id}

Use the instanceId from step 2.

Expected Response:

Shows workflowDefinitionName, currentStateId as draft

History is an empty list

4. Execute Action: "submit"

Endpoint: POST /api/WorkflowInstance/{id}/execute

Request Body:

{
  "actionId": "submit"
}

Expected Response:

Status: 200 OK

Message: "Action executed successfully"

Instance state changes from draft to review

5. Execute Action: "approve"

Endpoint: POST /api/WorkflowInstance/{id}/execute

Request Body:

{
  "actionId": "approve"
}

Expected Response:

Status: 200 OK

Message: "Action executed successfully"

Instance state changes from review to approved

6. Invalid Action Test (After Final State)

Endpoint: POST /api/WorkflowInstance/{id}/execute

Request Body:

{
  "actionId": "submit"
}

Expected Response:

Status: 400 Bad Request

Message: "Action cannot be executed from current state: approved"

7. Get All Workflow Instances

Endpoint: GET /api/WorkflowInstance

Expected Response:

List of all instances

Each entry includes id, currentStateId, createdAt, updatedAt

8. Get All Workflow Definitions

Endpoint: GET /api/WorkflowDefinition

Expected Response:

List of all defined workflows

9. Get Workflow Definition by ID

Endpoint: GET /api/WorkflowDefinition/{id}

Use the definitionId from step 1.

Expected Response:

Complete workflow definition with states and actions