An Overview of All API Types
Today’s developers use many different kinds of APIs to build their applications, especially cloud-native microservices-based applications.
An API (short for ‘Application Programming Interface’) is a software intermediary or layer that enables two applications to speak to one another.
As an example, every time you open up an app like Instagram to direct message someone or view a profile, you’re using an API. Each time you do something on Instagram, your phone will send data to a server over the internet.
This data acts as a request (e.g., for information) to the server. The server will then read your request and respond back to your phone with the data or information it needs to carry out your task. The process managing the communication is the API.
A simple analogy would be that of a restaurant. You’re the customer and you want to order food from the kitchen (i.e., server). You’ll call up a waiter (i.e., the API) to take your order to the back and, in turn, the kitchen will ask the waiter to send the food to you.
In this blog post, we’ll take a look at each of the major different API types.
A Look at Each Type of API
REST (short for ‘Representational State Transfer’) is a web services API. REST APIs are a key part in modern web applications, including Netflix, Facebook, and many others.
For an API to comply with REST (i.e., be RESTful), it must follow the following 6 rules:
REST APIs do not allow the server (or receiving end) to retain the information they receive from the client/sender. The client sends information to the server in packets that the server can understand in isolation (i.e., without context from past packets).
- Client-Server Architecture
The client and server of a REST API should both be independent of each other. In other words, the changes you make on the server shouldn’t affect the client (and vice-versa).
This is called the “separation of concerns” and it enables each side to grow and scale on its own without needing (or affecting) the other.
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The client side of a REST API should have the ability to cache or store information for a certain period of time. This reduces the number of times the application needs to call on the API and, in turn, reduces server usage and saves resources.
Caching also enables developers to improve the user experience of their applications by making them faster and more efficient.
- Uniform Interface
- Layered System
The REST API should use different architecture layers, each contributing towards a clear hierarchy. Each layer is loosely coupled, which lets you encapsulate legacy code in one part of the API, while changing another part of the API to a new technology.
- Code on Demand
Code on Demand is an optional rule. It allows you to transmit code within an application through the API. However, because modern Web APIs use multiple languages, Code on Demand hasn’t caught on due to security and efficiency risks.
An RPC (Remote Procedure Call) APIs are the oldest and simplest types of API. The goal of an RPC is for the client to execute code on a server. The main benefit of RPC APIs is they make it easier for developers to create applications involving multiple programs or services.
There are two main types of RPC APIs:
These are the simplest API types. You can develop them by formatting your data in XML and, in turn, making simple requests to the server via HTTP.However, though easy to develop, XML-RPC APIs are tightly coupled. To make changes, a new developer would have to go through the XML-RPC’s documentation to understand how a change in one area could affect another.
A JSON-RPC is basically an RPC API coded in JSON. Like XML-RPC, JSON-RPC APIs are easy to develop and implement, but they too are tightly coupled, which makes it just as difficult to maintain or update as XML-RPCs.
A SOAP (Simple Object Access Protocol) API is similar to REST in that it’s a type of Web API.
SOAP entered the web development scene in the late 1990s, around the time service oriented architecture (SOA) took-off. SOAP was the first to standardize the way applications should use network connections to manage services.
SOAP is an official protocol defined by the World Wide Web Consortium (W3C) and it comes with strict rules, especially in terms of security. As an example, you must integrate ACID and other compliance measures into SOAP APIs.
However, those added security requirements make SOAP complex and, in some situations, very resource intensive. With the exception of niche use-cases, most developers prefer developing in REST (thanks to its lightweight architecture and emphasis on speed and efficiency) over SOAP.
More Tips on Kickstarting Your Cloud-Native Application Development:
- What Does Applications Modernization Mean?
- The Advantages and Disadvantages of Microservices
- Grasping Software Architecture: Monolithic vs Microservices
Today, APIs play a key role in the development of microservices applications. But to effectively use APIs in cloud applications, you also need to deploy many powerful — and complex — tools, such as containers, container orchestration systems, service meshes and more.
This is a challenge for every IT team, big or small, when they lack experience and expertise in cloud development or cloud services. Building that knowledge base alone could eat away at precious time, which your competitors can use to not just take the lead, but take over the market.