ESB vs. Microservices: Understanding Key Differences

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We're delving into ESB vs. Microservices. The Enterprise Service Bus (ESB) has reigned for more than a decade as the preferred method for connecting monolithic business applications. However, with digital transformation and cloud-services rising to the forefront – forethinking enterprises are racing to achieve greater agility. They're doing this by (1) breaking up monolithic applications into “microservices” and (2) loosely connecting them to establish a “pluggable,” service-based infrastructure.

While ESBs continue to play a vital role in connecting monolithic business applications and supporting enterprise IT infrastructures, but the microservices movement is fundamentally changing the way enterprises manage their tech resources. 

However, the term “microservices” is often mischaracterized so we'll explain ESB vs. microservices in simple terms that anyone can understand.

Here are the key things to know about ESB vs. Microservices:

    • ESBs (enterprise service buses) are a centralized middleware that facilitates communication and integration between various services and applications within an enterprise.

    • Microservices are an approach to building applications that focuses on breaking down monolithic applications into independent, but loosely-connected “microservices.”

    • ESBs and microservices are both architectural approaches for integrating applications, but they have different strengths and weaknesses.

    • ESBs are better suited for integrating monolithic applications, while microservices are better suited for building scalable and resilient applications.

    • The best approach for an enterprise will depend on its specific needs and requirements.

What is an ESB?

To fully understand ESB vs. microservices, it’s important to look at both technologies separately. We’ll start with a brief explanation of ESB (enterprise service bus) technology.

ESBs establish data connections between monolithic applications. They provide users with a host of pre-built software adapters. ESBs also offer a secure and “pluggable” app integration hub that establishes a communication pathway between essential enterprise business systems. In this way, ESBs eliminate the need for custom-code, point-to-point integrations in many cases –  which speeds up system upgrades, facilitates adding/removing applications, and boosts overall business agility and growth capabilities. 

How do ESBs Work?

Enterprise Service Bus (ESB) works as a centralized middleware that facilitates communication and integration between various services and applications within an enterprise. It acts as a message broker, handling the routing, transformation, and mediation of messages exchanged between services. ESB enforces loose coupling, allowing services to interact without direct dependencies, and provides features like message queuing, service discovery, and protocol transformation to ensure seamless communication across the system.

Benefits of ESBs

ESBs offer several benefits in managing service-oriented architectures and integrating enterprise systems:

    1. Centralized Communication: ESB provides a central point for managing communication and integration between various services and applications, simplifying the process of connecting disparate systems.

    1. Protocol Transformation: ESB can handle different communication protocols, allowing services using different technologies to interact seamlessly.

    1. Message Routing: ESB efficiently routes messages to their intended destinations, enabling flexible and dynamic service interactions.

    1. Message Transformation: ESB can transform messages between different formats, ensuring data compatibility between services.

    1. Service Orchestration: ESB supports the orchestration of multiple services to perform complex tasks, streamlining business processes.

Key takeaway: The most important thing to remember about ESBs for this guide is that they focus on connecting the monolithic applications that serve an enterprise – and each of these applications performs a variety of services

What are Microservices?

The microservices architecture is an approach to building applications that focuses on breaking down monolithic applications into independent, but loosely-connected “microservices.” These microservices work together as a “pluggable” structure you can use to form an enterprise IT infrastructure.

How Do Microservices Work?

In a Microservices architecture, the application is composed of multiple services that can be developed, deployed, and scaled independently. These services communicate with each other using well-defined APIs, often leveraging REST (Representational State Transfer) or message queues.

Benefits of Microservices

As long as you have a way to connect and integrate the microservices together (usually with an iPaaS), you can program them in different languages, use disparate technology, and run them on different platforms. This makes development easier because (1) your team has the freedom to develop new microservices with their existing skillsets; and (2) you can choose whatever implementation technology best fits the performance requirements of the microservice.

Since each microservice can run independently, there is less chance that the failure of one service will result in the failure of the entire ecosystem. Even when one microservice synchronously invokes another. Using features like circuit breaker will stop the failure of one service from cascading throughout the application. This prevents resource exhaustion while the calling service waits for the failed service to respond – thus bolstering the resilience of the entire ecosystem.

Because microservices run in isolation from each other, sensitive information – like health data, financial data, business records, and other confidential information – is easier for developers to contain and protect from hacks and inadvertent exposure. Since developers maintain full control over access to the data in each microservice, achieving HIPAA and GDPR compliance is a faster and less expensive proposition.

Key takeaway: Whereas ESB technology builds an IT infrastructure by connecting applications (that perform multiple interdependent services), the microservices architecture connects a “hive” of “pluggable,” autonomously-running services.  

ESB vs. Microservices

In monolithic applications, an ESB connects all the features and functionality of each application run interdependently within a single instance. The monolith houses all of the code for each of the functions and services it performs. 

Monoliths start small, but as requirements grow, development teams bolt new functions on top of each. This happens until the monolith becomes interdependent, complex and difficult to untangle. This interdependence is problematic when making upgrades or changes. The code from different development teams working on different areas of the application invariably conflicts and collides. Ultimately, this happens until it’s impossible to manage application improvements. 

Eventually, it’s necessary to recode the entire application from scratch. Doing this is costly and could detract from other business priorities. Alternatively, you can dismantle the monolith into its component parts, and create a microservices architecture. 


A microservices architecture is different because the application exists as a network of small, autonomously running services. These microservices communicate with each other to create the larger application – usually by sending HTTP requests to their respective APIs. 

In this way, the microservices application is a honeycomb of “pluggable” services. They allow you to quickly develop, add, or remove features without affecting the larger whole.

Key takeaway: The microservices application architecture breaks down the traditional, monolithic application into its component parts because doing this allows them to run securely, and independently from each other. This provides a more agile framework for enterprise IT infrastructures because you can quickly, and inexpensively make adjustments to your suite of services in response to changing business requirements.

Defining Characteristics of Microservices

In this paragraph we'll define the characteristics of a microservices application:

    • Exists as a network of connected, modular components that perform separate functions or “services” within the application.

    • Each function or service meets a specific business need.

    • Each microservice operates independently, so it's easy to add, update, delete or switch out services without affecting the rest of the application.

    • The connected microservices that make up an application can be written in different programming languages.

    • Microservices are deployable on cloud servers and data centers, making it easy to quickly integrate new cloud-based microservices into an application.

    • When deployed on a scalable cloud platform, the latest cloud-based SaaS services are immediately available to your enterprise. 

    • Adding new microservices (or application functionality) does not affect the operation of other functions, so upgrades are simpler and easier to perform.

The Best Path to Take

A common architectural design pattern for a microservices architecture is to implement HTTP/REST with JSON. Microservices API connections are secure and reliable, but they are kept as “loose” as possible to facilitate the “pluggability” of services. Loose connections also prevent one service failure from negatively affecting the whole application. 

As for running and managing a microservices architecture, containerized environments and container orchestration are an excellent fit. By running each microservice in a separate container that houses the minimum-required executables and libraries for the service, each microservice is contained within a distinct, isolated environment. Integration with other microservices occurs by answering calls through a kernel or container orchestration tool. 

Docker is a popular solution for containerized environment and container orchestration. Kubernetes is also growing in popularity for container orchestration. 

Key takeways: The secret to integrating a microservices architecture lies in APIs exposed as REST/HTTP endpoints alongside JSON. Containerized environments and container orchestration also play an important role in running, managing, and integrating individual microservices.

Microservices in Action: Real-World Examples

With the rise of microservices, enterprises now have four paths to establish an IT infrastructure:

    1. A single monolithic application: A single monolithic application for all business systems (highly inefficient). 

    1. Multiple monolithic applications: An array of monolithic applications connected through an ESB – the traditional method (the prevailing model). 

    1. Hybrid ESB/microservices: A mix of monolithic applications and cloud-based microservices connected via ESB and iPaaS (where enterprises are currently headed).

    1. Full microservices: A complete microservices architecture where each business function runs as a compartmentalized, yet integrated service (the future).

Let’s look at three real-world examples of the last two microservices-based infrastructure paths into action:

1. Netflix

Netflix began adopting the microservices model in 2009 after scaling challenges led to frequent service outages. They were breaking down their monolithic application structure before the term microservices had even been coined, and their transformation began.

Netflix began by moving its non-customer facing movie encoding system to the Amazon AWS cloud, and over the two years, the platform moved all of its customer-facing web services to AWS. By 2012 the transition was complete, and Netflix consisted of hundreds of interconnected, cloud-based microservices. Netflix’s willingness to embrace the microservices movement is one of the most important contributors to the platform’s extraordinary growth.

2. SoundCloud

SoundCloud initially developed its platform as a monolithic Ruby on Rails application nicknamed “the Mothership.” The Mothership allowed hundreds of thousands of musicians to collaborate and share their music. However, SoundCloud faced scaling challenges that it couldn’t resolve with band-aid patches.

Instead of dismantling the Mothership completely, SoundCloud simply stopped adding features.  They started using separate microservices to add the new functionality they required. Gradually, SoundCloud started removing different functions from the monolith, replacing them with microservices. This has allowed SoundCloud to grow more freely with production-ready features and shorter feedback cycles.

3. Uber

Like SoundCloud and Netflix, Uber started as a monolithic application. As Uber experienced rapid growth, it experienced some struggles. They struggled to add new features, resolve bugs, and overcome technical debt in a single software depository (storage location for software packages). Moreover, developers required in-depth knowledge and experience with existing systems just to make a single change.

Drawing inspiration from Netflix and other rapid-growth companies, Uber decided to divide its monolithic application into multiple codebases to create a microservices architecture. Uber chose the microservices approach with the goals of “promoting clear ownership, offering better organizational scalability, and providing more resilience and fault tolerance through [its] commitment to microservices.” 

ESB vs. Microservices: Key Similarities

ESBs and microservices are both architectural concepts used to design and manage distributed systems, and they share some common principles despite their differences. One of the primary similarities is their focus on promoting loose coupling between services.

Whether you’re using a strictly microservice architecture or an ESB/microservice hybrid, we'll walk through how incorporating microservices into your operational strategy brings great benefits.

Both ESB and microservices aim to minimize direct dependencies between components, allowing each service to operate independently and be updated or replaced without affecting the entire system. This loose coupling enhances flexibility and maintainability, making it easier to evolve and scale the architecture over time.

ESB vs. Microservices: Key Differences

Here's a brief overview of the key differences between ESB and microservices:

    1. Definition and Purpose:

    • ESB: An Enterprise Service Bus is a middleware infrastructure that provides a centralized communication and integration platform for various services within an enterprise. It acts as a mediator, enabling different systems and applications to communicate and exchange data in a standardized and loosely coupled manner.

    • Microservices: Microservices is an architectural style that structures an application as a collection of small, independent, and loosely coupled services. Each service is dedicated to a specific business capability and can be developed, deployed, and scaled independently. Microservices promote the idea of breaking down complex applications into smaller, manageable components, making it easier to develop, maintain, and scale the system.

    1. Communication:

    • ESB: In an ESB architecture, communication between services often goes through the central ESB. Services connect to the ESB, and the ESB handles the routing and message transformation to ensure proper communication between services.

    • Microservices: Microservices communicate with each other directly, typically through lightweight protocols like HTTP/REST or messaging systems. There is no central component like an ESB; instead, each microservice knows how to interact with other microservices based on agreed-upon APIs.

    1. Centralization vs. Decentralization:

    • ESB: ESB provides a centralized approach to integration, where all communication flows through the ESB, allowing for centralized monitoring, logging, and management of services.

    • Microservices: Microservices advocate a decentralized approach. Each microservice operates independently and has its own database and domain logic. This decentralization allows for more flexibility and autonomy in development and deployment.

ESB vs. Microservices: Which is Best?

“If it ain’t broke, don’t fix it,” is a maxim that certainly applies here. Therefore, If your enterprise is running smoothly with an ESB and a suite of connected monolithic applications – there’s no reason to embrace the microservices revolution (yet).

On the other hand, here are some indicators that you’re ready for microservices: 

    • Growth hurdles: You’re facing growth hurdles because of bloated, monolithic applications that aren’t flexible or scalable enough to fulfill your changing business requirements.

    • Scaling challenges: You need the scaling flexibility of a cloud-based ecosystem that can handle real-time data integrations and massive data volume.

    • Building IoT networks: You’re building an IoT network with thousands or millions of IoT endpoints and the massive horizontal scaling requirements and large-volume data demands require cloud-based solutions. 

    • Advanced BI: You want to tap into more advanced ML and AI business intelligence that requires the powerful computation abilities of a cloud-based server. 

    • More focused app development: You’re building an application or software-as-a-service solution that provides a variety of services, but you want to focus your time on building one unique microservice. You can complete the application by adding the prebuilt microservices that support it.

    • Save money and time: You want to increase business agility, and save money and time when updating your IT infrastructure.   

In conclusion, If you’re ready to embrace microservices movement, consider using an iPaaS (integration platform as a service) platform. You'll be able to incorporate new microservices into your IT infrastructure while leaving your monolithic applications intact. From there, embark on the gradual process of isolating application functions into flexible, agile, and scalable cloud-based microservices.

DreamFactory: Automated, No-Code, API Generation for Your Microservices Architecture

Whether you’re trying to maximize the efficiency and agility of your enterprise IT infrastructure or building a new SaaS platform – the DreamFactory iPaaS offers a point-and-click, no-code interface that simplifies the process of building a microservices application architecture.  Try DreamFactory for free and start building APIs for microservices immediately. 

Frequently Asked Questions: ESB vs Microservices

What is an ESB?

An ESB is a middleware infrastructure that acts as a centralized communication platform in service-oriented architectures. It facilitates the integration of various services and applications within an enterprise, providing message routing, transformation, and mediation.

How do ESBs Work?

ESBs work as a message broker, handling the exchange of messages between services. They enforce loose coupling, enabling services to communicate without direct dependencies. ESBs also support protocol transformation, message queuing, and service orchestration to streamline communication.

What are Microservices?

Microservices are an architectural style that structures an application as a collection of small, independent services. Each service represents a specific business capability and operates independently. Microservices promote scalability, flexibility, and easier maintenance.

How Do Microservices Work?

Microservices work by breaking down a complex application into smaller, autonomous components. These services communicate with each other through lightweight protocols like HTTP/REST or messaging systems. Microservices allow independent development, deployment, and scaling of each service.

ESB vs. Microservices: Which is Best?

The choice between ESB and microservices depends on the specific requirements and complexity of the application. ESBs are suitable for centralized integration and legacy systems, while microservices offer more flexibility, scalability, and autonomy in distributed systems. Each approach has its trade-offs, and the decision should consider factors like organizational needs and development preferences.

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