1. A client-side user interface,
2. A server side-application,
3. A database.

It is unified and all the functions are managed and served in one place. If developers want to update or change something, they access the same code base. So, they make changes in the whole stack at once.

The application is packaged and deployed as a monolith.

Benefits of the Monolithic Architecture

1. Simple to develop
2. Easier debugging and testing
3. Simple to deploy. You just have to copy the packaged application to a server.
4. Less cross-cutting concerns. Cross-cutting concerns are the concerns that affect the whole application such as logging, handling, caching, and performance monitoring. In a monolithic application, this area of the functionality concerns only one application so it is easier to handle it.

Problems with the Monolith

The monolith is the giant program that has everything in it. Some of these things can be 500,000 or a million lines of code. They are very complicated and hard to deal with. And in fact, that complexity is the biggest problem of the monolith. There are a lot of internal connections and a lot of dependencies that make it almost impossible to work on. As a result, the monolith is very, very hard to update because of all the internal dependencies. It’s also hard to deploy just because it’s so large. It can take days sometimes to deploy a full-size monolith.

2. Microservices Architecture

The idea of the microservice is to take that monolith and make it tractable, to solve some of the problems associated with them. The microservice breaks the monolith up into a series of small services that talk to each other across the network.

Amicroservice architecture consists of “suites of independently deployable services” organized “around business capability, automated deployment, intelligence in the endpoints, and decentralized control of languages and data.”

Advantages of Microservices

1. Small. Something that you can understand fully simply by looking at the code.
2. it’s independently deployable. able to deploy a specific service without having to redeploy the system as a whole, which is a huge advantage over a monolithic system.
3. Hide it’s implementation details. In other words, if you, service A, know-how service B works, if service B changes you don’t want to have to change service A.
4. Modeled around business concepts. Is modeling the business concepts, is modeling the domain. So there’s a direct mapping there.
5. They are decentralized.
6. Highly observable.
7. Autonomous. they are highly isolated from one another.

Disadvantages of microservices

1. Complex testing over a distributed environment.
2. Distributed system. There are a lot of connections between multiple modules and databases. Therefore, requests, transactions, data management must be handled very carefully.
3. There is a higher chance of failure during communication between different services.
4. The developer needs to solve the problem, such as network latency and load balancing.