Top 10 Microservices Design Patterns and Principles

Microservices have emerged as the go-to method for building applications in today's market. Most companies prefer Microservices architecture while developing a business application rather than a monolithic design. As a result, understanding Microservice Architecture (MSA) and some design patterns are essential. 
So, let's take a quick look at what microservices are and their design patterns in this article. The design patterns listed below will provide you with an excellent introduction to Microservice Architecture Design Patterns.

Microservices Design Patterns and Principles: Table Of Content

1. What is Microservices?

2. Microsoft Architecture 

3. Microservice Principles

4. Microservices Design Patterns

What is Microservices?

Microservices, also known as microservice architecture, is an architectural approach that organizes an application as a series of interconnected services. Microservices are designed to accelerate the speed with which applications are released by breaking them down into small, self-contained services that can be delivered independently.

• Maintainable and testable to a high degree
• Loosely linked is a term that refers to a relationship that is
• Easily deployable
• Organizational structure centered on business capabilities.
• A small group of people owns it.

The microservice design allows huge, sophisticated applications to be delivered quickly, often, and reliably. It also enables a company's technology stack to adapt.

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Microsoft Architecture   

The microservice architecture is a collection of small autonomous services organized around the business domain. All of the components of a microservice architecture are self-contained and wrap around a single business capability.
The relevance of microservice design over monolithic architecture is described in four primary concepts listed below.

• High visibility – MSA improves the visibility of your services.
• Enhances resilience - Our service network's resiliency is enhanced.
• Reduced production time - Shorten the time it takes for an idea to become a finished product.
• Lower costs - Lower the entire cost of creating, deploying, and maintaining information technology services.

Essential Microservice Principles

The following are the key microservices ideas and design patterns that you can use to tackle common microservice architecture difficulties. Let's have a look at the ideas that underpin the microservice architecture.

• Independent & Autonomous Services
• Scalability
• Decentralization
• Resilient Services
• Real-Time Load Balancing
• Availability
• Continuous delivery through DevOps Integration
• Seamless API Integration and Continuous Monitoring
• Isolation from Failures
• Auto -Provisioning

These elements are the backbone of any reliable microservice architecture and must be considered when creating a microservice-based design. These characteristics speak to the microservice's independent and isolated nature, critical for its implementation.

What are the design patterns of microservices?

Microservices design patterns are known to tackle a variety of problems.  As a result, in this blog on Microservices Design Patterns, We'll go through the most important patterns for building a successful Microservices architecture, and we'll go over each one in-depth.

1. Aggregator
2. API Gateway
3. Backend For Frontend (BFF)
4. Command Query Responsibility Segregation (CQRS)
5. Event Sourcing
6. Circuit Breaker
7. Externalized Configuration
8. Consumer-Driven Contract Tracing
9. Strangler
10. Saga

Related Article: Microservices Tutorial for Beginners

1. Aggregator

The aggregator pattern is a microservice implementation method in which the same UI page invokes numerous services to accomplish the necessary functionality. This method comes in handy when combining data from multiple microservices into a single output. The Aggregator pattern is depicted in the diagram below in the microservice design.

As shown in the diagram above, an aggregator is a composite capability that combines numerous microservices. It might be a UI that requires functionality from three microservices, or it could be a bundled service with some business logic API. Because the aggregator microservice is based on the DRY principle, we may abstract logic in composite microservices and aggregate that reason in a single microservice.

Advantages of the aggregator design pattern

The following are some of the advantages of employing the aggregator design pattern:

• Tunneling microservices on both the x- and z-axes are scalable.
• Internal Services benefit from the signature flexibility of microservices.
• Providing microservices with a single point of access

Disadvantages of the aggregator design pattern

The following are some disadvantages of employing the aggregator design pattern:

• Data orchestration is complex.
• Anti-pattern of bottlenecks
• Communication latency between microservices

2. API Gateway   

The UI links to various Microservices in Microservice Architecture. If the Microservices are finely grained, the Client may need to connect to many Microservices, which can be noisy and complex. The services, as well as their APIs, can also change. Large businesses will welcome other cross-cutting concerns (SSL termination, authentication, authorization, throttling, logging, etc.).

One solution to these problems is to use API Gateway. It can serve as a reverse proxy, routing client requests to the appropriate Backend Microservice. It can also fan out a client request to numerous Microservices and return the aggregated replies to the client. It also helps to address important cross-cutting issues.

The API gateway design pattern is shown in this diagram. Microservices use service discovery to determine the best communication path between them. Microservices connect over a stateless server, such as an HTTP Request/Message Bus.

Advantages of the API gateway design pattern

• Microservices for the frontend and backend can be loosely coupled.
• Reduce the number of calls back and forth between the client and the microservices.
• SSL termination, authentication, and authorization provide high security.
• Logging and monitoring, throttling, and load balancing are examples of cross-cutting concerns that are centrally managed.

Disadvantages of the API gateway design pattern

• In Microservice Architecture, this might result in a single point of failure.
• Due to the additional network call, there is an increase in latency.
• They can quickly become a bottleneck for the entire Enterprise if they are not scaled.
• Additional development and maintenance costs.

Related Article: Microservices vs. API

3. Backend For Frontend (BFF)

  

The front-end and Backend apps are decoupled and independent Services in modern business application development, particularly in Microservice Architecture. The Backends for Frontends paradigm could be utilized in cases where each UI has its backend tailored to it. Other benefits include acting as a Facade for downstream Microservices, which reduces chatty interactions between the UI and downstream Microservices. The BFFs are also utilized to give additional security in a highly secured scenario when downstream Microservices are placed in a DMZ network.

Advantages of the BFF Pattern

• Concerns of the BFFs are separated. We can tailor them to a specific user interface.
• Increase the level of security.
• Reduce the amount of chatter between the UIs and the downstream Microservices.

Disadvantages of the BFF pattern

• Duplication of codes among BFFs.
• If numerous additional UIs are adopted, BFFs will be a proliferation (e.g., Smart TV, Web, Mobile, Desktop).
• BFFs should not contain any business logic and only client-specific logic and behavior, requiring careful design and implementation.

4. Command Query Responsibility Segregation (CQRS)

The CQRS design pattern can be beneficial to run a complicated query that covers many service databases because data access is confined to a single database. The program will be broken into two sections in this pattern: command and query. All requests for Create, Update will be handled by the command portion, whereas the query section will take materialized views. This implies the command component will be in charge of creating, updating, and deleting statements, while the query part will be in the order of the reading statements. The diagram below should assist you in comprehending the CQRS design pattern.

Advantages of CQRS

• Data reading in Event-driven Microservices is faster.
• Data with a high level of availability.
• Both read and write systems can scale independently.

Disadvantages of CQRS

• The read data store is inconsistent (eventual consistency)
• The system's overall complexity increases. Cargo culting CQRS has the potential to ruin the entire enterprise.

5. Event Sourcing

The event sourcing is in charge of generating a new, sequential sequence of events. The application state can be recreated by querying the data, but we must reimage every change to the program's condition to do so. The principle behind event sourcing is that the system should catch any change in the state of an entity.
A business item's persistence is achieved by storing a succession of state-changing events. Every time an object's state changes, a new event is added to the sequence of events. Because it's a single operation, it's virtually atomic. The current state of an entity can be reconstructed by replaying its occurrences.

Advantages of Event Sourcing

• Give extremely scalable systems atomicity.
• Entity history is kept automatically, and time travel is possible.
• Microservices that are loosely connected and event-driven.

Disadvantages of Event Sourcing

• Reading entities from the Event store becomes difficult and frequently necessitates the use of a separate data store (CQRS pattern)
• The system's total complexity grows, necessitating Domain-Driven Design.
• The system must handle duplicate events (idempotent) and missing events.
• It becomes challenging to migrate the event Schema.

Related Article: Top Microservices Tools

6. Circuit Breaker

The Circuit Breaker pattern interrupts any working activity by stopping the request and response process if the service is not working. When it comes to service-oriented notions like Microservices, this is critical. The caller requests a microservice without knowing whether or not the service endpoint is active. It continuously retries the call if no response is obtained. When a customer calls many microservices, or there is a workflow involving multiple microservices, and one of them fails to answer, the problem becomes even worse.
A circuit breaker pattern is used to avoid such instances, in which the client calls a proxy instead of a service directly. As a circuit barrier, the representative will act. When the number of failures reaches a certain level, the circuit breaker trips for a certain amount of time.

Advantages of Circuit Breaker

• Improve the Microservice Architecture's fault tolerance and resilience.
• Stops failures from spreading to other Microservices.

Disadvantages of Circuit Breaker

• Exceptions must be handled in a sophisticated manner.
• Monitoring and logging
• Manual reset should be possible.

7. Externalized Configuration

Every business application has a plethora of infrastructure configuration settings. In addition, in an enterprise setting, the program is typically deployed in multiple runtimes (Local, Dev, Prod). It poses a significant security concern because production credentials are easily compromised. Furthermore, any change in a configuration parameter necessitates a rebuild of the Application. 
This is very important in Microservice Architecture because there could be hundreds of services. Externalizing all Configurations is a superior strategy. As a result, the build process and the runtime environment are separated. It also reduces security risks by only using the Production configuration file at runtime or via environment variables.

Advantages of Externalized Configuration

• Production settings are not included in the Codebase, reducing security risks.
• Changes to configuration parameters can be made without requiring a new build.

The disadvantage of Externalized Configuration

• We must select a framework that can handle Externalized Configuration.

8. Consumer-Driven Contract Tracing

The Consumer Microservice owner team creates a test suite for a specific Provider Microservice that includes the Request and expected Response (for synchronous communication) or expected messages (for asynchronous communication). Explicit Contracts are the name given to these test suites. Provider Microservice's Consumer Contract test suites are included in its automated test. When an automated test for a certain Provider Microservice is conducted, it runs its tests and the Contracts and verifies them. In this method, the contract test can assist in maintaining Microservice Communication's integrity in an automated manner.

Advantages of Consumer-Driven Contract Tracing

• If the Provider makes an unexpected modification to the API or Message, it is discovered quickly on its own.
• Less surprise and higher resiliency, especially in enterprise applications with many Microservices.
• Team autonomy has improved.

Disadvantages of Consumer-Driven Contract Tracing

• Contract testing in Provider Microservice will take more time to build and integrate because they may use multiple test tools.
• It's possible that if the Contract test doesn't match real-world Service use, production will fail.

9. Strangler

The Strangler design closely resembles a vine that strangles the tree wrapped around. When a regular migration from a traditional application system to modern architecture is undertaken, the system requires extensive code rewrite processes. In such circumstances, the Strangler pattern can assist in gradually deprecating a legacy system and gently introducing new functionality rather than taking the entire system offline and doing a comprehensive overhaul. This means that two independent apps (Original and refactored) will coexist in the exact location. The refactored application will wrap around or strangle the original application until the actual application is shut down.

Advantages of Strangler

• A safe conversion from monolithic to microservices applications.
• The migration and the development of additional functionality can both happen simultaneously.
• The migration procedure can proceed at its speed.

Disadvantages of Strangler

• It becomes difficult to share data between the existing Monolith and the new Microservices.
• The system’s latency will be increased by adding a Facade (API Gateway).
• End-to-end testing gets more challenging.

10. Saga

In Microservice Architecture, the Saga pattern can be used for distributed transactions. Saga is a pattern created in 1987 as a conceptual alternative for long-running SQL database transactions. However, a recent variation of this design also works wonders for dispersed transactions. The Saga pattern is a local transaction sequence in which each transaction modifies data in the Data Store and broadcasts an Event or Message within a single Microservice. An external request initiates the initial transaction in a saga. The published message/event begins the next local transaction in the Saga after the local transaction is completed.

Advantages of Saga

• A highly scalable or loosely linked, event-driven Microservice Architecture provides consistency using transactions.
• When using NoSQL databases without 2PC support in a Microservice Architecture, provide surface through transactions.

Disadvantages of Saga

• It should be able to manage transitory failures and give idempotency.
• Debugging is complex, and the complexity increases as the number of Microservices grows.

Conclusion

As a result, this blog on Microservices Design Patterns comes to an end. We hope you've learned a lot about Microservice's design patterns and how they are effective in Microservices' specialized design requirements.