Four ways to integrate legacy systems

Legacy systems are a fact of life for most businesses today. Even the biggest, most cutting-edge companies have some legacy applications.

In this article, we'll examine four different methods that can help you integrate your legacy applications into your current operations, including enterprise service bus (ESB), application programming interfaces (API), integration platforms (iPaaS) and robotic process automation (RPA).

Enterprise service bus (ESB)

An ESB is a software layer that allows different applications to communicate with each other. It can be used to integrate a large number of applications and systems, including legacy systems, cloud applications and mobile apps.

The ESB architecture consists of five main components:

  • Messaging bus: Tracks what messages need to be sent between two or more components in real-time.
  • Service registry: Stores information about available services so developers can use the service during development and deployment phases.
  • Service repository: Stores metadata about all the services that are available for use in an organization, such as their description and capabilities (the types of data they can handle).
  • Business activity monitor (BAM): Monitors activity across multiple business assets to provide near-real-time visibility into a business process or system's health state based on key performance indicators (KPIs).
  • Application server gateway (ASG): Enables developers to connect applications using web services protocols such as SOAP over HTTP/HTTPS

Application programming interfaces (API)

An API is a set of programming instructions that allow software components to communicate with each other. These APIs can be used to integrate different systems and applications, allowing for greater flexibility and functionality in the end product. They are commonly used in modern software systems and you may have seen APIs in action without knowing it: when you install an app from the App Store or Google Play Store on your smartphone, your phone communicates with these third-party applications through an API that allows them to function as promised.

APIs are also widely used in cloud computing environments since they provide a way for data storage services (e.g., Dropbox) to interact with their users’ data while still maintaining privacy policies around this information.

Integration platforms (iPaaS)

Integration platforms (iPaaS) are a good choice when you want to integrate systems without the need for a lot of coding. These solutions usually have a high learning curve, so be sure that your team is ready to learn and apply new skills before choosing them over other methods.

In general, iPaaS solutions are more expensive than other options, but they can save time and money in the long run if they're used properly.

Robotic process automation (RPA)

RPA is a type of software that mimics human actions. It can be used to automate tasks that are repetitive, rule-based and predictable. RPA can be used to automate processes and activities in the back office.

When used correctly, RPA can cut down on manual errors while increasing process efficiency by up to 50%.

RPA is particularly useful for automating business processes that involve complex logic or decision making. This includes tasks such as:

  • Customer support calls or emails with pre-defined responses;
  • Processing incoming invoices;
  • Handling requests for approval from management;

Understanding the pros and cons

  • ESB: This method is a centralized hub for connecting different applications. It's often used to connect legacy systems with modern ones and can be useful in large-scale integration projects.
  • API: An API (application programming interface) is a method of communication between applications. It's typically used when creating new apps from scratch, but some companies use it as an addition to ESBs because they need more control over their integration processes than an ESB would provide them with. APIs are also great for integrating apps across different platforms since they're usually standardized across multiple types of software, like Android and iOS devices or Windows PCs versus Macs.
  • iPaaS: An iPaaS (integration platform as a service) provides developers with tools that allow them to build, test and deploy applications quickly without having to worry about infrastructure or other technical aspects related specifically towards integrating legacy systems into newer ones at scale - which might not be ideal given how complex these tasks can become!


If you’re looking to integrate your legacy systems, there are many different methods to choose from. Each has its own benefits and drawbacks, so it’s important to know what they are before deciding which one is right for your business.

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