**Course Title:** API Development: Design, Implementation, and Best Practices **Section Title:** API Versioning and Maintenance **Topic:** Implement API versioning in the existing RESTful API. (Lab topic) **Overview** In this lab, we will implement API versioning in an existing RESTful API. API versioning is an essential aspect of API management, as it allows you to manage changes to your API without breaking existing integrations. We will explore the different versioning strategies and implement URI versioning in our existing API. **Objectives** * Understand the importance of API versioning * Learn different API versioning strategies * Implement URI versioning in an existing RESTful API * Learn how to handle different versions of an API **Pre-requisites** * Familiarity with RESTful APIs * Understanding of API design principles * Knowledge of Node.js and Express (for the lab exercise) **Why API Versioning?** API versioning is crucial to ensure that changes to your API do not break existing integrations. As your API evolves, you may need to make changes to the API endpoints, request/response formats, or business logic. Without proper versioning, these changes can break existing integrations, leading to frustrated users and lost business. **API Versioning Strategies** There are several API versioning strategies, including: 1. **URI Versioning**: Including the version number in the URI (e.g., `/v1/users`) 2. **Header Versioning**: Including the version number in a custom header (e.g., `Accept-Version: v1`) 3. **Query Parameter Versioning**: Including the version number as a query parameter (e.g., `users?version=1`) 4. **Media Type Versioning**: Including the version number in the media type (e.g., `application/vnd.example.v1+json`) **Implementing URI Versioning in the Existing API** For this lab, we will implement URI versioning in an existing RESTful API using Node.js and Express. We will create a new route `/v1` and update the existing endpoints to include the version number. **Lab Exercise** Create a new folder for your lab project and initialize a new Node.js project using `npm init`. Then, install Express and create a new file `app.js` with the following code: ```javascript const express = require('express'); const app = express(); // Existing endpoints app.get('/users', getUsers); app.get('/users/:id', getUser); app.post('/users', createUser); app.put('/users/:id', updateUser); app.delete('/users/:id', deleteUser); // Versioned endpoints app.get('/v1/users', getUsersV1); app.get('/v1/users/:id', getUserV1); app.post('/v1/users', createUserV1); app.put('/v1/users/:id', updateUserV1); app.delete('/v1/users/:id', deleteUserV1); // Implement versioned endpoint logic here... // Existing endpoint logic... function getUsers(req, res) { // ... } function getUser(req, res) { // ... } // ... ``` **Bonus Exercise** Implement header versioning and query parameter versioning in your existing API. You can use the `Accept-Version` header or `version` query parameter to determine the version number. **Conclusion** In this lab, we implemented URI versioning in an existing RESTful API using Node.js and Express. API versioning is an essential aspect of API management, and there are several strategies to choose from. By implementing versioning, you can manage changes to your API without breaking existing integrations. **Additional Resources** * [SemVer](https://semver.org/) for versioning guidelines * [Express documentation](https://expressjs.com/en/guide/routing.html) for routing and middleware information **Leave a comment below if you have any questions or need help with the lab exercise!** In the next topic, we will explore **Introduction to cloud platforms for API deployment (AWS, Heroku, etc.)**.