If you have been in the industry for more than six to eight years, monolithic applications are not new to you. Even today, a lot of old applications that are in production follow monolith design architecture. Well, let's try to understand what a monolith design is and what the word monolith means to you.

If you look at these definitions and try to apply them to a software application, it will be clear what we mean when we say the application follows a monolith design. We are talking about the following characteristics:

• Single: In the case of an application, we are talking about a single piece of code or a deployable. An application that can and should be deployed on a single machine.
• Indivisible: We cannot break the application down; there is no easy way to divide the application code or deployable.
• Slow to change: This is more of an implication of monolith design. It is a well-known fact that changing a small piece of code is easier than a big, monolith code, especially since you don't know what implications such a change will have.

The following diagram shows the architecture of a monolithic design based on a Java application:

We can see the whole application is deployed as a single deployable, that is, a WAR or EAR file. The design looks very simple, but it does hide a lot of complexities. The single deployable, in this case, a WAR file or EAR file, might have a lot of functionality implemented.

Let's take an example: say we have to implement an application for our company where we can manage data for employees. Let's call this the Employee Management System, which should be able to handle core requirements such as maintaining employee data, project data, hierarchy, attendance, leave data, salary, and financial information. In addition to these core requirements, our application would also handle additional requirements, such as reporting needs for management.

In a monolith design, we code all this functionality and build it into a single deployable. If you have been in the software industry for more than 10 years, you have probably seen and worked on some applications that follow this design. The design has been good for small and simple applications, but as the complexity of the application increases, it gets challenging to manage a monolith design.