RESTful API Explained: The Ultimate Guide (Part 1)

At the outset, allow me to share that RESTful APIs are designed to be stateless. This means that each request contains all the necessary information for the server to understand and fulfil the request. This allows for scalability and simplicity in the design of the API.

REST is the use of hypermedia, which involves including links in the API response that allow clients to navigate to related resources.

I’m sure you’re curious to know more. Let’s begin!

Key Concepts of REST API

REST is a robust and commonly used approach for crafting web services that prioritize simplicity, scalability, as well as ease of use.

Fig 1: Key concepts of REST API

• Platform independence: REST API allows clients to interact with web services using standard HTTP methods. This can be easily implemented on different platforms and programming languages. This makes it easier to develop web services that can be accessed by a wide range of clients.
• Scalability: REST API is designed to be stateless. This means that each request contains all the necessary information for the server to understand and fulfil the request. This allows for scalability and simplifies the REST API design. It can handle large amounts of traffic without impacting performance.
• Flexibility: REST API allows developers to design APIs that can be used for a wide range of purposes, including data retrieval, data manipulation and even authentication. This makes it possible to build powerful web services that can be used in a variety of contexts.
• Interoperability: REST API is based on open standards such as HTTP, JSON, and XML. This makes it possible for different systems to communicate with each other. This enables the development of integrated systems and services, which can be accessed by a variety of clients.
• Ease of use: REST API is designed to be easy to use, with simple and consistent interfaces that are easy to understand and work with. This makes it easier for developers to build web services and for clients to use them.

Now, allow me to explain how REST API works.

How REST API Works

It’s time for a REST API example!

Let’s take an example of building an e-commerce platform.

Here we must create a REST API to allow users to create, read, update, and delete product data from the collection.

Here, we can create a structure of REST as shown below.

1. Define the resources and their URLs:

• Products: /products
• Individual Product: /products/{productid}

2. Define the HTTP methods to perform CRUD operations on the product:

• GET: Read a product
• POST: Insert a product
• PUT: Update a product
• DELETE: Delete / Remove a product

3. Implement the API endpoints:

• GET /products: Returns a list of all products.
• POST /products: Inserts a new record of a product.
• GET /products/{ productid }: Display a product’s properties with the input ID parameter.
• PUT /products/{ productid }: Updates the entire product properties with the input ID parameter.
• DELETE /products/{ productid }: Deletes the product of input ID parameter.

Create:

To create a new product, you must make a POST request to the /products endpoint with the data for the new product in the request body. The server would create a new product and return a response with the HTTP status code 201 (Created) and the URL of the newly created product in the Location header.

Display:

To display an information about a specific product, you will make a GET request to the /products/{productid } endpoint with the ID of the product you want to retrieve. The server would return a response with the HTTP status code 200 (OK) and the product data in the response body.

Update:

To update an existing product, you have to make a PUT request to the /products/{ productid } endpoint with the updated data for the product in the request body. The server would update the product and return a response with the HTTP status code 200 (OK).

Delete / Remove:

To delete a product, you have to make a DELETE request to the /products/{ productid } endpoint. The server would delete the product and return a response with the HTTP status code 204.

Let’s turn to the design principles now.

RESTful API Design Principles

When designing a RESTful API, it is important to follow certain principles. These are to ensure that the API is easy to use, scalable and maintainable. Here are some key design principles for RESTful APIs:

Fig 3: Key design principles for RESTful APIs

• Use resource-based URLs: RESTful APIs are based on resources. So, it’s important to use URLs that reflect the resources being accessed. This makes it easier for clients to understand the structure of the API and navigate it.
• Use HTTP methods correctly: The HTTP methods (GET, POST, PUT, DELETE, etc.) should be used correctly for their intended purposes. For example, use GET for retrieving resources and POST for creating resources. Use PUT for updating resources and DELETE for deleting resources.
• Use HTTP status codes correctly: HTTP status codes should be used correctly to provide meaningful feedback to clients about the status of their requests. For example, use

1. 200 for successful requests
2. 201 for successful resource creation
3. 404 for resource not found
4. 400 for bad requests
5. 500 for server errors

• Use JSON for data exchange: JSON (JavaScript Object Notation) is a lightweight and easy-to-use format for data exchange in RESTful APIs. It’s also widely supported by different programming languages and platforms.
• Support filtering and sorting: RESTful APIs should provide support for filtering and sorting resources. This is to make it easier for clients to retrieve the data they need. This can be done using query parameters in the URL.
• Use hypermedia: Hypermedia (links) should be used to provide clients with information about related resource and actions that can be taken on those resources. This makes the API more discoverable and easier to use.
• Version your API: As your API evolves, it’s important to version it. This is to ensure that clients can continue to use older versions while new versions are developed. This can be done using version numbers in the URL.

Overall, following these design principles can help ensure that your RESTful API is easy to use, scalable and maintainable over time.

REST does have certain cons. Here they are.

Cons of REST

Here are some of the cons of REST:

• Statelessness: REST is designed to be stateless, meaning that it does not retain any information about the client between requests. While this can make the system more scalable, it can also make it more difficult to implement certain features, such as sessions or user authentication.
• Performance issues: In some cases, REST can be slower than other approaches, such as RPC (Remote Procedure Call), due to the overhead of transmitting data over HTTP.
• Limited support for real-time communication: REST is primarily designed for request-response communication and does not provide built-in support for real-time communication, such as WebSockets.
• Lack of discoverability: While REST provides a standard way of accessing resources, it does not provide a standardized way of discovering them. This can make it difficult for clients to find and use resources in a system.

Now, what about the future? Let’s take a look.

The Future of REST API

RESTful APIs have become a standard way to build web services. They are widely used in various applications, from mobile apps to IoT devices. The future of REST API is expected to continue growing and evolving, driven by the following trends:

Fig 4: Trends driving the future of REST API

• Microservices architecture: The trend towards microservices architecture has increased the use of RESTful APIs to enable communication between different RESTful services. This allows organizations to break down their applications into smaller, more manageable services. These can be developed, deployed, and scaled independently.
• Internet of Things (IoT): IoT devices are increasingly using RESTful APIs to communicate with each other and with the cloud. RESTful APIs allow devices to send and receive data over the internet in a standardized way. This makes it easier to build and scale IoT applications.
• Artificial Intelligence (AI) and Machine Learning (ML): RESTful APIs are being used to integrate AI and ML services into applications. This allows developers to use pre-built AI and ML models and services. The purpose is to enhance their applications without needing to build the models themselves.
• GraphQL: GraphQL is a query language that enables clients to request exactly the data they need, and nothing more, from an API. It is becoming increasingly popular as an alternative to RESTful APIs. The reason is, it offers more flexibility and allows clients to avoid over-fetching and under-fetching data.
• Serverless computing: Serverless computing is where applications are built and run without the need to manage servers. Its rise has increased the use of RESTful APIs as the communication layer between services. Serverless architectures often rely on API Gateway services to handle the routing and security of requests.

RESTful APIs are likely to continue to play an important role in the development of web services. It is driven by the increasing demand for microservices, serverless computing, IoT, and AI and ML integration. As the technology and tools for building RESTful APIs evolve, developers will continue to find new ways to create robust and scalable applications.

Can REST get replaced in the future?

It’s important to note that RESTful APIs have been around for many years and have proven to be a reliable and flexible way to build web services. There are some emerging technologies and approaches that are gaining popularity. Those could potentially replace REST in the future. Here are a few examples:

• GraphQL: GraphQL is a query language for APIs that was developed by Facebook. It allows clients to request only the data they need and is often seen as a more efficient and flexible alternative to REST.
• gRPC: gRPC is a high-performance, open-source RPC framework that was developed by Google. It uses protocol buffers for serialization and is designed to be fast, efficient, and language independent.
• Event-driven architectures: Event-driven architectures are becoming increasingly popular. They are relevant especially in the context of microservices. In this architecture, services communicate with each other using events rather than request/response interactions.

Emerging technologies are not necessarily direct replacements for RESTful APIs, and in many cases, they may be used alongside RESTful APIs. For example, GraphQL can be used to query data from a RESTful API. gRPC can be used to handle low-latency, high-throughput communication between microservices.

Well, I trust you enjoyed getting acquainted with REST!

To know more and to make it a go-to practice in your daily development tasks, delve into the best practices of Restful API in part 2 of my blog.

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