Introduction to REST API

Before starting about REST API let’s see what an API is.

What is API?

API is the acronym for Application Programming Interface, which is a software intermediary that allows two applications to talk to each other. Now, Let’s see what is REST API

What is REST API?

REpresentational State Transfer (REST) is an architectural style that defines a set of constraints to be used for creating web services. REST API is a way of accessing web services in a simple and flexible way without having any processing. All communication done via REST API uses only HTTP requests.

How the RESTAPI works?

The REST API works almost in the same way as any website. The call is made from the client to the server, and the data is received back via the HTTP protocol. You can also use them to provide means of accessing resources available on the server required for the client through the web browser by using request headers, request body, response body, status codes, etc.

HTTP Methods

HTTP methods or HTTP verbs form the main part of uniform interface constraint, followed by REST, which determines what actions have to be followed to get the requested resource. The most common methods include GET, POST, PUT, and DELETE.

• GET retrieves resources.
• POST submits new data to the server.
• PUT updates existing data.
• DELETE removes data. The verbs map to CRUD operations. With the two principles we discussed above in mind, we should create routes like GET /articles/ for getting news articles. Likewise, POST /articles/ is for adding a new article , PUT /articles/:id is for updating the article with the given id. DELETE /articles/:id is for deleting an existing article with the given ID.

Handle errors gracefully and return standard error codes

Common error HTTP status codes include:

• 400 Bad Request — This means that client-side input fails validation.
• 401 Unauthorized — This means the user isn’t not authorized to access a resource. It usually returns when the user isn’t authenticated.
• 403 Forbidden — This means the user is authenticated, but it’s not allowed to access a resource.
• 404 Not Found — This indicates that a resource is not found.
• 500 Internal server error — This is a generic server error. It probably shouldn’t be thrown explicitly.
• 502 Bad Gateway — This indicates an invalid response from an upstream server.
• 503 Service Unavailable — This indicates that something unexpected happened on server side (It can be anything like server overload, some parts of the system failed, etc.).

Best REST Clients and Testing Tools

Swagger

Swagger is an API testing tool that allows users to start their functional, security, and performance testing right from the Open API Specifications. Some pros:

• Supports API documentation, development, design, and testing.
• Swagger offers many open source features for the OpenAPI specification.

Postman REST Client

With Postman, you can monitor the API, create automated tests, perform debugging, and run requests. Some pros:

• Smooth automated testing.
• Co-working features for easy sharing and management.
• Supports Swagger and RAML files.

Katalon Studio

Katalon Studio provides a common place to create and perform API/Web services, UI functional, and mobile testing. Some pros:

• Has one of the most secure assertion libraries.
• It’s a complete package and framework.
• Supports a data-driven approach.