Recently, organizations have started to move toward a new approach for the development of their applications. This approach focuses on the development of the application when composed of several small services that are good at providing a single functionality and providing it well. These small services are known as microservices.

These microservices model the functionality of a subset of an enterprise domain. For example, there could be a service in the infrastructure that is responsible for handling the user credential and authentication, another service that could be handling the functionality of emails, and yet another service that processes the paychecks of the employees.

All of these services communicate over the network by the mechanism of passing messages or through making API calls from one service to another service through the use of APIs exposed by the service so as to achieve a particular use case.

Now, in contrast to traditional applications that were large and required middleware that could handle the transformation of the data from the format supported by one application to the one supported by another application and then transporting that data securely, microservices require either an API through which one service can directly talk to the other or a small message broker through which the data can be transported from one microservice to another in the form of messages.

This has changed how Enterprise Application Integration used to happen, because now, there are no complex middleware solutions present in the infrastructure providing the glue layer to connect the different applications inside the infrastructure.

So, let's take a look at why the traditional approaches do not work in the microservices architecture and try to understand the new alternatives that have come up to facilitate the integration of application in the enterprise.