All about Microservices and it's design patterns

Microservices have become one of the solutions for building an application. various problems can be solved using microservices. but still, many skilled professionals still face difficulties using this architecture. so in order to overcome this developers can find suitable patterns in these problems and they need to create solutions that are reusable so that they can improve the performance of the application. so in this blog microservices design patterns, I will explain detail about major patterns necessary to build successful microservices.

What are Microservices?

It is an architectural style in which applications are gathered as a collection of small autonomous services modeled around the business domain. each service in the microservice architecture is self-contained and implements only one business capability. in this blog, I'm going to explain four major design patterns of Microservices like Aggregator, API Gateway, chain of responsibility, asynchronous messaging

Aggregator pattern:

The term Aggregator in the computer world indicates a website or program that gathers relevant items of data and displays them. even in microservices patterns. it is a basic web page that provides various services to get relevant information or achieve the required functionality. 

Also since the output source is separated about breaking monolithic architecture at microservices. this pattern proves to be useful when you need an outcome by combining data from various services. so let's assume if we have two services each having its own database then an aggregator having a unique transaction-id would gather data from each individual microservice implement as a business need after some time data collected can be used by the respective services for that collected data is required. Mostly this design pattern is based on the dry principle. by following this principle, you can abstract away the logic of complex microservices and combine that custom business logic into a single service.

API Gateway design patterns:

Microservices are built on the way that each of their services has individual functionality. but when their applications are cut down into small services then there may be a few difficulties developers can face. these problems could be as follows

1. How I can get information from multiple microservices?
2. Various UI requires various data to respond to the same backend database service
3. How to process data according to the consumer needs from reusable microservices
4. How to manage multiple protocol requests?

How to solve this problem? then the solution could be API Gateway Design Pattern. not only the above-mentioned concerns API Gateway design pattern solves many other problems. this design pattern is also considered a proxy service to route a request to the required microservice. unlike aggregator service, it can send requests to various services and likewise aggregate the output back to composite or the consumer service. API gateway also functions as a beginning point for all the microservices and creates fine-grained APIs for various types of customers.

with the support of the API Gateway design pattern they can convert the protocol request from one type to another Additionally, it can likewise offload the verification/approval obligation of the microservice.

so once a customer sends a request, these requests are passed to API Gateway. which act as a beginning point to carry forward the customer requests to accurate microservices then with the support of a load balancer a load of request is managed and the request is sent to the appropriate services. microservices use service discovery which performs as a tourist guide to find the appropriate direction of communication between each of them. microservices use a stateless server like HTTP request/message bus for communication among them.

Chain of Responsibility Pattern:

Chain of Responsibility Pattern delivers a solitary result which is a mix of various chained outputs. So, if you have three services arranged up in a chain, then, the request from the customer is first received by Service A. Then, this service communicates with the next Service B and gathers information. In the end, the second service interacts with the third service to create a combined result. All these services use either synchronous HTTP requests or responses for messaging. Also, until the request is accepted through all the services and the respective responses are generated, the customer doesn’t get any results. So, it is always recommended not to make a long chain, as the customer will wait until the chain is finished. one of the major aspects everyone needs to understand is that demand from Service A to Service B might appear to be unique from Service B to Service C. Likewise the reaction from Service C to Service B might appear to be totally unique from Service B to Service A.

Asynchronous Messaging Design Pattern:

The above-mentioned pattern uses synchronous messaging. in that customer need to face a lot of difficulties like sometimes they get blocked or need to wait for a long time. so if you want your customers need not wait for long hours then you can opt for Asynchronous Messaging. in this type of design pattern all the services can communicate with each other but at the same time, it is not required to communicate with each other in an ordered way. So, if you consider three services: Service A, Service B, and Service C. The request from the customer can be directly sent to Service C and Service B at a time. These requests will be in a queue. Apart from this, the request can also be sent to Service A whose response need not have to be sent to the same service through which request has come.