In modern architecture, monolithic architecture and applications have become a thing of the past, and every organization is moving forward to break them down. After all, moving away from monoliths is a logical decision since its more complicated and there are also many dependencies and issues with deployment and testing.

For most developers, microservices seem like the most obvious solution to replace monoliths. But in this article, we will be discussing how self-contained systems can also be a successful option for breaking down monoliths.

Microservices

One of the most obvious benefits of microservices is that it allows users to do continuous deployment and change, debug, or replace a part of the application without affecting the rest of the application. Using microservices architecture means, if anything goes wrong in a part of the application, it is contained in that very part, and the rest of the application continues to work without a glitch.

However great microservices may sound, transforming a monolith into microservices architecture is easier said than done. Depending on the size of the monolithic core, it can take a few months to years, just to convert a monolithic core into multiple microservices.

Pros

•     Maintaining microservices is comparatively much easier because each one of them has its own purpose and built with a laser-like focus on that very purpose. It also allows developers to jump in and out of microservices quickly. They are easy to run and quick to deploy.
•     Since all the microservices in an application are isolated from each other, if one part fails, it does not affect the other and does not lead to downtime. For instance, even if the microservice that handles adding new orders is down, your customers would still be able to check the status of their existing orders.

Cons

•     Every application may have hundreds of microservices, making them operationally complex. Developers cannot manage it all at once on the same server or deploy them one by one. Instead, they will require automation to handle everything.
•     Communicating messages from one microservice to another takes a lot of effort because developers need to make sure the data is transferred sensibly and consistently. More often than not, you will have to create a new microservice to handle transfer and authentication of data.

Even with those cons, microservices are still preferred over monoliths. The initial time taken to break down a monolith into microservices may be a lot but after that, what you get is an easy to manage architecture.

Though, if the initial costs and time for creating microservices is a lot for your organization and handling monolithic applications has become incredibly complicated, you might want to consider the self-contained system as an option.

Self-Contained System

Self-Contained Systems (SCS) are similar to microservices in the way that they allow you to breakdown a monolith into smaller and independent parts. But, there are many differences between SCS and microservices:

•     In SCS, you break a monolith down into replaceable and autonomous web applications, which isn’t the case with microservices
•     The SCS units are within software and larger than microservices
•     SCSs have their own autonomous user interface (UI), data storage, and business logic, making them more customizable than microservices
•     While API level integration of SCS is possible, UI level is a more preferred integration

Since SCS is bigger than microservices, when you break down a monolith, creating SCSs takes much lesser time than microservices. Instead of being a complete redesign, SCS makes an application more agile by dividing it into small steps to reduce chances of failure.

Pros

•     One of the biggest advantages of a self-contained system is that you can build several SCS units, each with different databases and languages.
•     With monolith broken down, you can easily handle the coding and deployment of the application. Since the data is internal, you do not need to worry about how messages get passed from one SCS unit to another.

Cons

The line between SCS and microservice does exist, but it is slightly blurry, which means, it can be difficult for you to define an SCS architecturally. There is a lot more planning that goes into it before you can begin to break a monolith down into a self-contained system

Choosing Between Microservices Vs Self-Contained Systems

If you want to break down a monolithic and your end goal is microservices, you could still start with a self-contained system and then move towards microservices. Though you have to be patient while breaking down SCS units to make your software more agile.

As mentioned above, planning is more important than ever otherwise you might end up with SCS units that get bulkier and bigger with time. If that does happen, you will have to start breaking them into microservices.