Monolith to Microservices

Background

In its original use, the term "monolithic" described enormous mainframe applications with no usable modularity.

In software engineering, a monolithic application describes a single-tiered software application in which the user interface and data access code are combined into a single program from a single platform. For example, a database full of tables or a client-side user interface with HTML pages or JS.

The design philosophy is that the application is not just responsible for a particular task, but can perform every step needed to complete a particular function.

A microservices architecture breaks the action into a collection of smaller independent units communicating with all the other user APIs (Application Programming Interfaces). These units carry out every application process as a separate service, so all the services have their logic and database as well as perform their specific functions.

Microservice vs Monolith

Some of the big cons of monolithic architecture are:

• Longer development process. It is harder to implement changes in such a large and complex application with very tight coupling. Any code change affects the whole system, so it has to be thoroughly coordinated. This makes the overall development process much longer.
• Scalability. You cannot scale components independently, only the whole application.
• New technology barriers. It is extremely problematic to apply new technology in a monolithic application because then the entire application has to be rewritten.

The microservices approach offers tangible benefits including an increase in scalability, flexibility, agility, and other significant advantages, such as:

• Utilizing 100% of the cloud. In concert with cloud technologies, using microservice architecture in a product can utilize the full range of the cloud capabilities, and empower products to work faster, better, and with less downtime.
• Independent components. - Services can be deployed and updated independently, which gives more flexibility.
• Resilience. - A bug or shutdown in one microservice has an impact only on the particular service and does not influence the entire application.
• Easier understanding. - Split up into smaller and simpler components, a microservice application is easier to understand and manage. You just concentrate on a specific service that is related to a particular business goal.
• Scalability. - Each element can be scaled independently. As a result, the entire process is more cost-time-effective than with monoliths, where the whole application has to be scaled even if this is unnecessary.
• Agility and more freedom of action. -It is much easier to add new features to a microservice application than to a monolithic one.

Which architecture suits you best?

It is a decision that must be made with extra care while considering what suits your business needs and software solution the best - both approaches have pros and cons. Choosing a monolithic architecture can benefit us if we are developing a small application that does not demand much business logic and scalability, small teams, a simple product, a need for a quick launch, or the need to create a simple POC. Choosing a microservices architecture will suit more complex applications, a product with a clear future plan for expansion, one that contains a variety of different services, and a large user base and data.

Migrating from Monolith to Microservices: Stop adding new services and features to your monolith. For the first few months, as your initial teams build out their microservices, it should be business as usual. Once you have some useful implementation patterns and have tailored the process to your organization, you'll want to create a plan for breaking apart the monolith.

At this point, carefully consider any changes you make to your monolith. If possible, add new features as microservices that are decoupled from your monolith.

Your first few microservices shouldn't rely on your monolith, otherwise, your new service will be bound to the monolith release cadence. At some point, however, your microservices will need to interact with your monolith. Try to keep the coupling as loose as possible, and to keep the monolith domain model out of your microservice.

Here at Compie we have already made several successful transitions of very complex and large monolithic applications to microservices, both on cloud and on-premises. Need help making such a transition for your products? Contact us and find out how our expert architects and tech leads can help!