What is REST?
REST (Representational State Transfer) can be defined as a set of guidelines that software uses to communicate over the internet for simple and scalable integrations. An API that follows these guidelines is known as a REST API (RESTful API).
When a client requests for a resource using a REST API, the server responds by transferring back the current state of that particular resource in a standardized representation. This means that REST APIs work by fielding requests for a resource and then returning all the relevant information about that resource. This information is translated into a format that clients can interpret without any issues.
REST is an architectural style or rather a set of guidelines. On the other hand, the OpenAPI specification is a standard way through which you can use text to describe the features of a REST API. For instance, if the postal code of a client can be retrieved using a REST API, then the OpenAPI specification will describe that API to show developers how to call the API in a way that it properly responds with the zip code that was requested.
Furthermore, if you would like to implement the OpenAPI specification with your API, you can use APITransform to upload your Postman collection to convert it to OpenAPI.
The Six Rules of REST APIs
1. Uniform Interface
This is a guideline that requires all requests and responses to follow a common protocol and provides a way through which messages are formatted. Since servers and applications come in different languages that make it difficult when it comes to working together, this uniform interface offers a common language for any client to interact with any REST API. If this was not there, then it would be a total mess to translate requests and responses between applications.
2. Client Server Separation
The server and the client can only interact in one way under the REST architecture. The client is mandated with sending a request to the server while the server can only send a response back to the client. All interactions between the two start from the client.
3. Layered System
Even though we have talked about API requests as just an interaction between the server and the client, there are typically many more servers between the two entities. These servers can be referred to as layers and provide security, handle traffic, and help in accomplishing different tasks. However, messages between the client and the server should be formatted the same way regardless of the layers that exist between them.
4. Stateless
Calls made within the REST API framework must be stateless. Apart from all the interactions being independent, each request and response must provide all the information that is required to complete an interaction. The server will not remember anything about past requests, meaning that it interprets every request as a new task.
5. Cacheable
When building REST APIs, developers are required to keep caching in mind. For instance, when a client makes a request and the server responds, the response needs to indicate if the resource provided can be cached and if it can, for how long.
6. Code on Demand
Even though this rule is not mandatory, it allows an API to send computer code to clients when responding to a request to allow the client to run the code in its backend.
An API that follows these rules is considered to be a RESTful API. If you look at some of the best marketing tools we have today, they have implemented APIs that adhere to all set rules required for them to be successful. Therefore, if you are looking into developing one, you need to adhere to these rules for your API to be successful.