The Critical Role of APIs in Microservices Architectures

February 2, 2023 Lakshmi Balu

The first thing to know when exploring APIs vs microservices is that there’s not a mutually exclusive relationship between these two technical approaches. Instead, you want to build an understanding of how these two technologies complement each other—and they do, in a big way.

Organizations don’t need to embrace either an API-first or microservices-first strategy. This is not an either-or situation, but rather, APIs and microservices are two components that help each other and make it possible to build software that is easier and faster to deploy today and update in the future. 

Microservices-based architectures often include an API model that allows services to communicate with each other. Using microservices, an application is broken up into smaller elements called services. While these services are interconnected, they are designed so that each service can work independently and serves only one business need. This “loose coupling” is an inherent aspect of a microservices-based architecture. APIs are the protocols that enable those services to communicate. Let’s dig into each of these concepts more deeply.

What are APIs?

APIs (short for application programming interfaces) are defined as a part of an application that talks with other applications, services, systems, and smart devices. They are not visible interfaces but rather they provide secure data migration and transfer between applications or services in the background. 

Modern software architectures—including cloud native architectures—must be fast, accurate, and easy to update and maintain. For an end user to access the functionality of an application, the average wait time should be as short as possible. An API-first model makes data transfer between services and applications as fast as possible. The right API design can improve the developer experience, especially when working with complex, distributed systems like microservices. Exposing data through the API layer improves data migration and quality, so developers don’t have to worry about it. Mastery of APIs is critical for companies that want to unlock innovation.

APIs: The connectors for continuous IT modernization and innovation 

With the ever-changing landscape of IT and application modernization, APIs are here to stay. World business leaders and technology analysts recognize the importance of APIs, as they can enable critical business outcomes, such as:

  • Code reusability/API reusability 

  • Cost effectiveness 

  • Higher ROI

  • Speed to market

There are several types of API architectures. Here are a few commonly used API formats:

  • RESTfull API (representational state transfer) – Lightweight protocols that are extensively used in mobile application development and Internet of Things (IoT) 

  • RPC (remote procedural call) – An action-oriented and lightweight protocol that is popular in client-server-based architecture

  • SOAP (simple object access protocol) – An older protocol, based on XML and popular in more monolithic architecture. However, it is expensive and generally not suitable for modern application development.

  • GraphQL (graph query language) – GraphQL APIs get all the data your app needs in a single request. Apps using GraphQL can be quick even on slow mobile network connections and have become particularly popular in this space.

What are microservices?

Microservices are an architectural design pattern in which a distributed application is built, with each application function operating as an independent service. 

The salient features of microservices architecture are:

  • An application is divided into smaller, loosely coupled services

  • Microservices are invoked from multiple clients through APIs

  • Infrastructures can be distributed across cloud and data centers 

  • Compartmentalization enables the adding and updating of new features without altering the entire application

Enterprise applications built in the past 20 years are often considered “monolithic” by today’s standards. These applications were often tasked with vast scopes and could not be updated frequently. Today, enterprise organizations want their applications to work securely and consistently across distributed systems, environments, and clouds. Many large enterprises, some functioning in highly regulated industries, are realizing tremendous improvements in application performance, security, stability, and scalability by breaking down tightly coupled, monolithic applications into sets of microservices. Cloud native architecture accommodates communication with other applications, devices, and end users via lightweight APIs. This allows developers to compartmentalize long, complex chunks of code into smaller chunks that are easier to change, update, or debug.

Of course, breaking down these monoliths is not a simple "rip and replace" matter, and every organization needs to evaluate its own individual needs, existing technology, organizational structure, and objectives, then design a thoughtful approach that makes sense for them. Fortunately, cloud companies like VMware have been partnering with big enterprise businesses to devise their innovation strategies and have been successful in implementing microservices and APIs to break down monolithic architecture into distributed and independent systems.

APIs in microservice architecture

Microservices using APIs are critical to achieving faster application development and delivery. APIs can empower microservices with the following capabilities:

  • Access and exchange data securely by providing an abstraction layer between the API consumer and the business logic 

  • Communicate and provide functionality to multiple applications and devices 

  • Ability to access APIs securely without resulting in any data leakage. In the case of confidential data like sensitive health care- or banking-related information, a secure API safeguards the data it processes by restricting its accessibility to only authorized applications, users, and servers. This ensures adherence to compliance frameworks like HIPAA and GDPR.

These factors make API-driven microservices-based architecture more reliable, sustainable, and manageable. 

Best practices for implementing microservices and APIs

Not every monolith needs to be replaced by microservices-based architecture. Business leaders need to evaluate organizational needs and determine whether they’ll see positive ROI from this kind of modernization undertaking. 

If so, they’ll want to follow some well-established best practices for implementing API-driven, microservices-based architecture. Here are a few to keep in mind:

  • Ensure management understands the logic behind adopting a microservices architecture, and evaluate its potential benefits, such as easy scalability and workload distribution to create a secure and fast-functioning application

  • Each microservice should be designed to execute a single business task

  • Instead of microservices calling other services for a specific function, APIs can do that on their behalf. APIs can communicate and deliver data without the microservices getting to know all the nuances of an API.

Microservices with APIs are the stepping stones to modernizing applications, but implementing them to help break down monoliths does not happen overnight, and the process must be carefully planned and expertly executed. Big players like Amazon and Netflix have excelled by implementing microservices, but others, such as Twitter and Airbnb, have said their own efforts to break down their monolithic architectures into microservices did not have the desired results.

Microservices-based, API-driven architecture is a proven digital transformation strategy, helping organizations become cloud agnostic. APIs are those catalysts that drive faster go-to-market without code conflicts, enabling each team of developers to push code with fewer interdependency issues. Finally, businesses that have adopted microservices-style architecture are better able to proactively respond to customer needs and innovate faster as their developers can furnish new features quickly when customers need them. 

To learn more about breaking down monolithic architectures and implementing microservices and APIs responsibility, see these resources:

About the Author

Lakshmi Balu

Lakshmi Balu is part of the field sales services team at VMware. She is passionate about the VMware Tanzu portfolio and is keen on tracking current trends in enterprise application development, ranging from financial tech and healthcare to high-tech verticals, and how VMware plays an important role in innovation in the digital space.

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