Microservices Design Patterns

What is Microservice Architecture?

Microservices is an architecture in which all system components are separated into distinct components that may be designed, deployed, and scaled independently.

Microservices, also known as microservice architecture, is an architectural approach that builds an application as a set of small autonomous services based on a business domain. Each service in a Microservice Architecture is self-contained and implements a single business feature. In recent years, the use of microservices in programming has risen, and in today's market, Microservices have become the go-to solution for building an application.

The following are some principles to follow when designing a microservice-oriented application.

• Independent: Each microservice should be deployable separately.
• Coupling: All microservices should be loosely connected such that changes in one do not affect the other.
• Business Goal: Each service unit in the application should be the smallest and capable of achieving a single business goal.
• Decentralized governance: Each team has autonomy in making decisions related to their specific microservice, promoting rapid development and innovation.
• Scalability: Microservices architecture allows for scaling individual services based on specific needs, improving overall system scalability.
• Resilience: Failure in one microservice does not impact the entire system, ensuring resilience and fault tolerance.
• Domain-driven design: Microservices are designed around specific business domains, enabling better alignment with business needs.

Service-oriented Architecture (SOA)

A service-oriented architecture will divide up large software packages into a number of tiny, interconnected business units. To bring effective business to the client, each of these small business units will communicate with one another via distinct protocols. Now, how does Microservice Architecture (MSA) differ from SOA? In a nutshell, SOA is a design pattern, while Microservice is a methodology for implementing SOA, or we might say Microservice is a form of SOA.

Design Patterns for Microservices Architecture

1. Decomposition Design Patterns

A large application will be divided into smaller microservices. Decomposition design patterns show you how to accomplish it logically.

• Decompose by Business Capability: We can create a microservice corresponding to a specific business capability. A business capability is a business activity that is designed to generate value.
• Decompose by Subdomain: Decomposing an application using business capabilities is an excellent place to start, but you will run upon so-called "God Classes" that will be difficult to decompose. Several services will share these classes. Define services that correspond to subdomains of Domain-Driven Design (DDD). The domain in DDD refers to the application's problem space - the business. A domain is made up of several subdomains. Each subdomain represents a different aspect of the business.
• Decompose By Strangler: We may define a microservice using the strangler pattern. There are two types of services in a strangler application.
  • Existing Behavior: These services display the previously included behavior in Monolith.
  • New Features: These services implement new behavior.

So, as development progresses, the number of microservices grows, and the monolith shrinks, with functionality flowing from the monolith to the Strangler Application.

2. Integration Design Patterns

Microservices might employ several protocols while building a large, complicated application using microservice architecture. Some microservices, for example, use REST, whereas others use AMQP. The difficulty now is figuring out how to let clients access each microservice without having to worry about protocols and other complexities. Integration design patterns handle these issues. For example, how to obtain the results of many services in a single call, and so on. API Gateway Pattern, Aggregator Pattern, Proxy Pattern, Gateway Routing Pattern, Chained Microservice Pattern, Branch Pattern, and Client-Side UI Composition Pattern are some popular examples of Integration Design Patterns.

3. Database Design Patterns

Database design patterns address how to create database architecture for microservices, such as whether each service should have its own database or use a shared database, and so on. Microservice architecture frames an application as a group of loosely linked microservices, and each service can be developed separately in an agile manner to enable continuous delivery/deployment. Database design patterns deal with the database structure/architecture used in a microservices-based application.

4. Observability Design Patterns

Observability design patterns take into account logging, performance metrics, and other factors. Requests frequently include numerous services. Each service instance logs information in a consistent format in its log file. These logs may be info, error, warning, or debug in nature. Observability design patterns deal with how to use these logs to investigate and troubleshoot application problems.

5. Cross-Cutting Concern Design Patterns

Service discovery, external configurations, deployment situations, and other issues are addressed in Cross Cutting Concern Design Patterns. These services frequently interact with infrastructure services or third-party services. A service registry, a message broker, and a database server are examples of infrastructure services. Payment services, email services, and messaging services are examples of third-party services.