Similarities, differences and how ESB and microservices relate to their respective architecture models.

Companies have been using the enterprise service bus (ESB) for decades to connect applications to each other. Typically, these applications were monolithic — built comprehensively by including all services needed within the app. Then came the expansion of cloud services and separate, pluggable microservices. Because microservices represent a fundamental shift in the way enterprises manage their resources, it’s helpful to explore the role both ESB and microservices play to understand the advantages of one over the other.

What is an enterprise service bus?

An ESB, or enterprise service bus, is an integration approach that uses a centralized software component to create integrations between applications. To create an ESB, developers build a communication bus between different applications. Then, they enable each application to talk to the bus, which in turn allows sharing of data and communications between the connected applications. This standardized approach to application integration means DevOps won’t have to build custom, point-to-point integrations for each application.

It helps to view ESB in the context of how it is used in the overall computing architecture. ESBs are the building blocks of SOA, or service-oriented architecture, an architecture approach designed to foster communication between services through loose coupling. SOA is the overarching approach to a system’s architecture, and ESB is the communication tool that makes the approach possible.

For more background on how ESB fits into SOA architecture, read “ESB and SOA”.

What are microservices?

Microservices are a cloud-native architecture approach in which a single application is composed of many independently deployable components, or services. A departure from the traditional, monolithic application approach of large, tightly coupled applications, microservices instead make use of containers. Using containers creates a scalable and distributed system that avoids the bottlenecks of a central database.

Microservices are separated by their business capability. For example, an application’s cart, customer data and product information are all stored within its own database and communicate in real-time through APIs, event streaming or messaging protocols to create the application’s overall functionality.

The key difference between ESB and microservices

The main distinction between ESB and microservices is that an ESB is an integration tool, while microservices are just as the name suggests — small service components that are combined to create an application.

An ESB is a centralized, standardized hub that inputs, transforms and outputs data so various applications and services can communicate easily. Microservices are free of dependencies on other microservices. They can be plugged in and out of applications as needed. While they take different approaches, ESB and microservices are after the same goal — make cloud-based application development and operations easier and more efficient.

To fully understand the difference between ESB and microservices, it’s helpful to look at not just how they compare, but also at how ESB and microservices relate to their respective architecture models.

A microservices architecture is made up of many highly specialized services that development teams connect to build an application’s functionality. As microservices architecture design continues to advance, the benefits of decoupling services increase; they are more agile, scalable and responsive to the needs of organizations today.

ESB, on the other hand, is a product initially designed for the pre-cloud, legacy system era. Integrations take longer to develop and are less flexible than if you take a microservices architecture approach. The centralized integration hub of an ESB can make troubleshooting problems easier than identifying the cause within your microservices. However, without fault tolerance, the ESB can also be a single point of failure for the whole enterprise, which results in a bigger overall problem to fix.

To learn more about the distinction between ESB and SOA architecture and microservices architecture, read, “SOA vs. Microservices: What’s the Difference?

ESB pros and cons

Some benefits and drawbacks of using ESB include the following:

  • Pro: You can easily reuse services. Once a service is connected via the ESB, those services can connect to others with minimum effort. 
  • Pro: Enables better governance and monitoring. Because ESB is a centralized hub for integrating applications, it can also serve as a central point to govern service usages and monitor statistics.
  • Pro: Deploying applications is simpler. All service routing and orchestration capabilities are built into the ESB, making deployment easier.
  • Con: Causes risk to availability. The bus itself can be a single point of failure because of an ESB’s central role in orchestrating all systems on the network.

Microservices pros and cons

Some benefits and drawbacks of using microservices include the following:

  • Pro: Gives DevOps more flexibility. Teams can use different stacks and different programming languages for different components.
  • Pro: Microservices enable agile development by allowing the addition of new features or functionality without changing the entire application.
  • Pro: Low dependencies between services means implementing continuous delivery is easier, and teams can deploy faster.
  • Pro: Components can be scaled independently without having to scale entire applications.
  • Con: Microservices are extremely flexible and agile, but they do create more complexity. With independent services deployed in more places, problems with one service can affect multiple applications.

Will microservices architecture replace ESB?

The short answer is no. An ESB can connect both small, specialized web services and older, enterprise-wide services and applications. This makes it the best solution for integrating large on-premises solutions with SaaS solutions and other cloud-based environments.

Yet, in recent years, microservices have become the preferred architecture model in many organizations. There are several reasons why microservices have the advantage over ESB and SOA today:

  • They can be changed independently to create greater agility.
  • They can be scaled independently to make better use of cloud-native infrastructure.
  • They can provide the resilience required for 24/7 online operations.

Here are some use cases for when microservices would be the preferred architecture approach:

  • Streaming services: The ability to rapidly scale up or down is essential for the large fluctuations in data and traffic that come with audio and video streaming applications.
  • Flexibility when adding new features: Consumers today are looking for constant updates and customizations. Microservices make adding new features easier because they enable DevOps to choose the language that best fits the skillset and the implementation technology that best fits the performance requirements.
  • Internet of Things (IoT): One IoT product can have millions of endpoints collecting data 24/7. Microservices, with their decoupled architecture and scalability, can help manage large-data demands that come with IoT.
  • Secure data: Using cloud services for data integration and storage can be complicated by regulations and compliance requirements. With microservices, data is run in isolation. Development teams maintain full control over the data, making compliance with HIPAA and GDPR easier.

While microservices have the edge today, ESB is likely to adapt architectural aspects of microservices to meet demand. The rise in container technology and the need to integrate multiple cloud environments will influence how ESB architecture is used and they ways in which it will evolve and become more modern.

ESB, microservices and IBM

As companies today look for an undisruptive solution to shift IT infrastructure toward the hybrid cloud, they will need a modern approach to integration. For many companies, this will include transforming workloads based on SOA and ESB patterns to a more lightweight and flexible model.

Companies can leverage the scalability and flexibility of the cloud by deploying independent microservices, while ensuring legacy systems remain relevant with evolving ESB offerings. Using automation can standardize the process, regardless of the approach, making the transition faster and more efficient. IBM gives you access to AI-powered Automation capabilities, including prebuilt workflows, to help accelerate innovation and digital transformations.

Take the next step

Learn how IBM Cloud Integration Solutions can speed integration development by up to 300%, reduce costs by over 33% and increase overall operational efficiency.

Explore modernizing integrations and leveraging middleware investments with IBM Cloud Pak® for Integration. This hybrid integration platform uses an automated, closed-loop approach that supports multiple styles of integration within a single, unified experience.

Get the full picture of where your organization needs to go to advance its integration technology. IBM’s Integration Maturity Assessment provides a critical look at your organization’s integration maturity and what actions you can take to get to the next level.


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