Node.js Workflow Library

This Node.js Workflow library is designed to manage workflows, control transitions, handle events and listeners, manage errors and rollbacks, define rules, provide extensible plugin support, and optimize performance. It is inspired by the Laravel Workflow library.

Features

• States: Represent different stages of the workflow.
• Transitions: Define transitions from one state to another.
• Events and Listeners: Events triggered at specific points in the workflow and listeners responding to those events.
• Error Handling and Rollback: Manage errors and perform rollbacks if necessary.
• Rule Engine: Define and evaluate rules for transitions in the workflow.
• Monitoring and Logging: Monitor and log the workflow.
• Internationalization and Localization: Support for multiple languages.
• Advanced Security Features: Provide user authorization and authentication.
• Extensibility: Extend the workflow using a plugin system.
• Performance and Scalability: Suitable for large-scale and high-performance applications.

Installation

npm install nodejs-workflow

Usage

Defining a Workflow

Create a workflowService.ts file and define the workflow:

import {WorkflowManager, State, Transition} from 'nodejs-workflow';

const workflowDefinition = {
    states: [
        {name: 'initial'},
        {name: 'in_progress'},
        {name: 'completed'}
    ],
    transitions: [
        {from: 'initial', to: 'in_progress', condition: 'canStart'},
        {from: 'in_progress', to: 'completed', condition: 'canComplete'}
    ],
    events: [
        {name: 'taskStarted', callback: () => console.log('Task started')},
        {name: 'taskCompleted', callback: () => console.log('Task completed')}
    ]
};

const workflowManager = new WorkflowManager(workflowDefinition, {storageType: 'memory'});
workflowManager.addRule('canStart', () => true);
workflowManager.addRule('canComplete', () => true);

export {workflowManager};

States and Transitions

To manage states and transitions:

workflowManager.transitionTo('in_progress');
console.log(workflowManager.getCurrentState()?.name); // 'in_progress'

Triggering Events

To manage events and listeners:

workflowManager.on('customEvent', () => console.log('Custom event triggered'));
workflowManager.triggerEvent('customEvent');

###Error Handling and Rollback To handle errors and perform rollbacks:

workflowManager.addRule('canStart', () => false);
workflowManager.transitionTo('in_progress');
console.log(workflowManager.getCurrentState()?.name);

Using Translations

To support multiple languages:

workflowManager.addTranslations('es', {'hello': 'hola'});
workflowManager.setLocale('es');
console.log(workflowManager.translate('hello')); 

User Authorization

To manage user authorization and authentication:

workflowManager.addUser({ id: 'user1', roles: ['admin'] });
workflowManager.authenticate('user1');
console.log(workflowManager.authorize(['admin']));

Using Plugins

To extend the workflow using a plugin system:

const customPlugin = {
    initialize: (workflowManager) => {
        console.log('Plugin initialized');
    }
};
workflowManager.registerPlugin(customPlugin);
workflowManager.initializePlugins();

API Integration and Swagger

To create an API with Express.js and document it with Swagger:

API Controller

Create a workflowController.ts file:

import {Request, Response, Router} from 'express';
import {workflowManager} from '../services/workflowService';

const router = Router();

/**
 * @swagger
 * /state:
 *   get:
 *     summary: Get current state
 *     responses:
 *       200:
 *         description: Current state
 */
router.get('/state', (req: Request, res: Response) => {
    const currentState = workflowManager.getCurrentState();
    res.json({currentState: currentState ? currentState.name : null});
});

/**
 * @swagger
 * /transition:
 *   post:
 *     summary: Transition to a new state
 *     requestBody:
 *       required: true
 *       content:
 *         application/json:
 *           schema:
 *             type: object
 *             properties:
 *               state:
 *                 type: string
 *     responses:
 *       200:
 *         description: Transition success
 */
router.post('/transition', (req: Request, res: Response) => {
    const {state} = req.body;
    try {
        workflowManager.transitionTo(state);
        res.json({success: true});
    } catch (error) {
        res.status(400).json({success: false, message: error.message});
    }
});

export {router as workflowRouter};

Swagger Configuration

Create a swagger.ts file:

import swaggerJSDoc from 'swagger-jsdoc';
import swaggerUi from 'swagger-ui-express';
import {Application} from 'express';

const options = {
    definition: {
        openapi: '3.0.0',
        info: {
            title: 'Node.js Workflow API',
            version: '1.0.0',
            description: 'A simple API for managing workflows'
        }
    },
    apis: ['./src/controllers/*.ts']
};

const swaggerSpec = swaggerJSDoc(options);

const setupSwagger = (app: Application) => {
    app.use('/api-docs', swaggerUi.serve, swaggerUi.setup(swaggerSpec));
};

export {setupSwagger};

Main File

Create an index.ts file:

import express from 'express';
import bodyParser from 'body-parser';
import {workflowRouter} from './controllers/workflowController';
import {setupSwagger} from './swagger';

const app = express();
const port = process.env.PORT || 3000;

app.use(bodyParser.json());
app.use('/api', workflowRouter);

setupSwagger(app);

app.listen(port, () => {
    console.log(`Server is running on http://localhost:${port}`);
});

Testing

Create a workflow.test.ts file:

import request from 'supertest';
import express from 'express';
import bodyParser from 'body-parser';
import { workflowRouter } from '../src/controllers/workflowController';
import { setupSwagger } from '../src/swagger';

const app = express();
app.use(bodyParser.json());
app.use('/api', workflowRouter);
setupSwagger(app);

describe('Workflow API', () => {
  it('should get the current state', async () => {
    const response = await request(app)
      .get('/api/state')
      .set('Authorization', 'your-secure-token');
    expect(response.status).toBe(200);
    expect(response.body.currentState).toBe('initial');
  });

  it('should transition to a new state', async () => {
    const response = await request(app)
      .post('/api/transition')
      .send({ state: 'in_progress' })
      .set('Authorization', 'your-secure-token');
    expect(response.status).toBe(200);
    expect(response.body.success).toBe(true);
  });

  it('should return 401 for unauthorized requests', async () => {
    const response = await request(app).get('/api/state');
    expect(response.status).toBe(401);
  });
});

Starting and Testing the Project

To start the project:

npm start

You can access the Swagger documentation at http://localhost:3000/api-docs.

Summary

This library provides a comprehensive and flexible solution for managing workflows. With its wide range of features, it can be used even in large-scale and high-performance applications. Its easy setup, flexible configuration, and powerful features ensure a user-friendly experience.

Example Project Structure

Here is an example of how you can structure your project to use the Node.js Workflow library:

markdown Copy code

Example Project Structure

Here is an example of how you can structure your project to use the Node.js Workflow library:

nodejs-workflow-example/
├── src/
│ ├── controllers/
│ │ └── workflowController.ts
│ ├── middleware/
│ │ └── authMiddleware.ts
│ ├── services/
│ │ └── workflowService.ts
│ ├── index.ts
│ └── swagger.ts
├── test/
│ └── workflow.test.ts
├── .gitignore
├── jest.config.js
├── package.json
├── tsconfig.json
└── README.md

Detailed File Descriptions

1. src/controllers/workflowController.ts: Manages the API routes for workflow operations.
2. src/middleware/authMiddleware.ts: Example middleware for handling authorization.
3. src/services/workflowService.ts: Defines the workflow using the Node.js Workflow library.
4. src/index.ts: Main entry point for the Express application.
5. src/swagger.ts: Configures Swagger for API documentation.
6. test/workflow.test.ts: Contains tests for the API using Jest and Supertest.
7. .gitignore: Specifies files and directories to ignore in the version control.
8. jest.config.js: Configuration file for Jest.
9. package.json: Lists dependencies and scripts for the project.
10. tsconfig.json: TypeScript configuration file.
11. README.md: Documentation for the project.

Additional Setup

To ensure everything is set up correctly, follow these steps:

1. Install Dependencies:

   npm install

2. Compile TypeScript:

npm run build 

3. Run Tests:

npm test

4. Start the Server:

npm start

5. Start the Application:

npm start

Example Middleware

Here is an example of an authorization middleware you might include in src/middleware/authMiddleware.ts:

import { Request, Response, NextFunction } from 'express';

export const authMiddleware = (req: Request, res: Response, next: NextFunction) => {
  const token = req.headers.authorization;
  if (token === 'your-secure-token') {
    next();
  } else {
    res.status(401).json({ message: 'Unauthorized' });
  }
};

Example API Calls

Once your application is running, you can test it using tools like Postman or curl. Get Current State

curl -X GET "http://localhost:3000/api/state" -H "Authorization: your-secure-token"

Transition to a New State

curl -X POST "http://localhost:3000/api/transition" -H "Authorization: your-secure-token" -H "Content-Type: application/json" -d '{"state": "in_progress"}'

Summary

This comprehensive guide provides all the necessary steps to set up and use the Node.js Workflow library effectively. By following these instructions, you can manage complex workflows in your applications with ease, leveraging features like state management, event handling, error handling, rule evaluation, and more. The integration with Express and Swagger ensures that your workflows can be exposed via a robust API with proper documentation.