Introduction
You may have heard the term API and wondered what it is and what it does. A web API is a set of tools that allow website developers to send and receive instructions and data by connecting to web servers. Many of the websites and web applications we use today are powered by APIs.
In web applications, front-end code does not communicate directly with the database. Instead, data is sent and received through a layer called an API. The API acts as an intermediary layer between the back-end, database operations, and the front-end applications that the user interacts with.
Essentially an API layer:
- Ensures that a web page is allowed to send and receive requests.
- It verifies the correct format of the request before sending it to the backend.
- Returns data in the expected format along with some additional information.
- Tells the web page why the data was not returned.
Types of APIs
There are different types of APIs with different levels of security and privacy. There are 4 main types of APIs, each of which we will explore below:
1- Public APIs
Public APIs, also known as external APIs, are made available to developers and other users with minimal restrictions. Using this type of API may require you to register and use an API key, or they may be completely open. This type of API is intended for external users to access data or services.
2- Internal APIs
Unlike open APIs, internal APIs are designed to be hidden from external users. They are used within a company to share resources. They allow different teams or departments of a business to consume each other's tools, data, and applications.
3. Partner APIs
These types of APIs are technically very similar to open APIs, but they have limited access and are often controlled through a third-party API gateway. They are usually intended for a specific purpose, such as providing access to a paid service.
4. Hybrid APIs
Hybrid APIs allow developers to access endpoints in a single call. This endpoint can have multiple endpoint properties in a single API, or it can be a service or resource. Hybrid APIs are especially useful in microservice architectures, where information from multiple services may be required to perform a task. Using hybrid APIs can reduce latency and improve user experience of an application, because a single call can return all the required items.
Types of API protocols
We can also categorize APIs by protocol type. An API protocol consists of rules that determine what information an API can share with clients and how it shares the data. RPC, SOAP and REST These are some of the most popular API protocols in use today. We will go into more detail about each of these protocols below.
Remote Procedure Call (RPC)
The RPC protocol is the simplest of the three architectures. Unlike REST and SOAP, which facilitate data transfer, RPC APIs invoke processes. In other words, they execute scripts on the server. RPC APIs may use JSON or XML in their calls.
Service Object Access Protocol (SOAP)
SOAP is a protocol for transferring data across a network and can be used to build APIs. SOAP specifies exactly how messages should be sent and what should be included in them. This makes SOAP APIs more secure than REST APIs.
Representational State Transfer (REST)
Most web APIs today are built on REST. REST is a set of guidelines for scalable, lightweight, and easy-to-use APIs. A REST API is an API that follows the REST guidelines and is used to transfer data from a server to a requesting client.
In summary, REST API guidelines include the following:
- Client-Server Decoupling: All client-server interactions should be in the form of a request from the client followed by a response from the server.
- Uniform interface: All requests and responses must use HTTP as the communication protocol and be formatted in a specific way to ensure compatibility between the client and the server.
- Independence: Each client-server interaction should be independent of other interactions. The server does not store any data from client requests and does not remember anything from past interactions.
- Layered system: Requests and responses must always be formatted in the same way, even when sent through intermediate servers between the client and the API.
- Cacheable: Using these guidelines, REST APIs can be used for fast, easy, and secure data transfer, making them a popular choice among developers.
Types of APIs in terms of use cases
Another classification for APIs can also be categorized in terms of use cases, which include:
open API
Structurally, open API is a standard format for defining the structure and syntax of standard REST APIs. Open API documents are both machine-readable and human-readable, allowing anyone to easily determine how each API works. Engineers can use open API to program and design servers, develop, and run tests.
API gateway
Most enterprise APIs are deployed through an API gateway. API gateways typically perform the typical tasks that are used in a system of API services, such as user authentication, rate limiting, etc. An API gateway service accepts a remote request and returns a response.
web API
An application known as a web API is a type of interface that has a set of functions. This set of functions allows programmers to access some specific features or data of an application. WEB API, as the name suggests, is an API that accesses the web using the HTTP protocol. It can help you create and develop REST services for HTTP.
What is the use of API?
As explained in the definition of what is an API, APIs enable companies to open up the data and functionality of their applications to external third-party developers, business partners, and internal departments of their company. This allows services and products to communicate with each other and use each other's data and functionality through a documented interface. Developers do not need to know how to implement an API. They simply use an interface to communicate with other services and products of the company.
What is an API key?
An API key is a unique identifier used to authenticate calls to an API. An API key is a string of letters and numbers that identifies the client. The key grants or denies requests based on the client's access permissions and tracks the number of requests made for usage and billing purposes. By restricting access to only those who have the key, a company can control the number of calls made to its API and ensure that only a specific, trusted group of customers can access its server resources.
GraphQL
GraphQL is an open source query language used to serve data to mobile and web applications. It is similar to REST in that it is used to fetch data for the application, but its approach to how the data is retrieved is completely different. While REST APIs are great and the most widely used, GraphQL introduces a new API technique that can be used to improve efficiency and flexibility.
What is the difference between software and API?
The biggest difference between software and APIs is how they affect the user. Both provide some form of connectivity, while APIs are intended for use by software programs, software programs are intended for use by humans.
APIs are usually just part of a particular piece of software, and most of the applications you use depend on multiple APIs in some capacity.
Apps, on the other hand, are much more flexible. Apps may use multiple APIs to help the user accomplish a task. APIs are designed to integrate easily with your software of choice and can be used specifically for workflows and individuals.
