Microservices have catapulted application development into a new era. Companies are quickly replacing their monolithic apps with microservices apps, breaking down large components into smaller, more manageable parts. As an architectural style, microservices are based on loosely coupled and independent services. Modularity, scalability, and flexibility are some of the leading benefits of microservices.
But you need to identify how your development team can leverage this architectural approach to reap maximum benefits. For this, you need to fully understand the various design patterns involved in microservices and how you can use these effectively.
This article explains the top five design patterns your DevOps team should know. It highlights the benefits and challenges of each design pattern of microservices architecture and explains how you can choose the right one for your project.
What are Microservices?
Microservices is an architectural approach to application development that develops apps as a set of independent and loosely coupled services. Each service represents a particular business functionality and can be developed, deployed, and scaled independently of other services. In this architecture, app services use proper APIs and protocols to interact with each other.
The goal of microservices is to create apps that are highly scalable and easy to manage, develop, and deploy. Monolithic apps, on the other hand, have interconnected and interdependent services that cannot be scaled, updated, or deployed independently of each other. This is why monolithic apps lack the scalability and flexibility factors associated with microservices.
Benefits of Microservices
Microservices has totally changed the app development landscape owing to the benefits it offers. Let’s take a look at some of these benefits.
One of the greatest drawbacks of monolithic apps is that there is no fault isolation – one faulty component can easily bring down the entire app. Microservices overcome this problem due to the independent nature of each service or component. Your development team can, therefore, handle each service or component failure in isolation from others without jeopardizing the entire app’s performance. All this means that microservices-based apps are more stable and resilient compared to monolithic applications.
Another incredible benefit of microservices apps is that you can deploy them independently. This implies that you can change any app component without having to make changes to the other services. However, if you change a monolithic app component, you must redeploy the entire application. This is risky and takes a lot of time as well. But with microservices, you can ensure CI/CD pipeline as it allows you to rewrite a service without impacting application performance, thus helping you maintain a top-notch DevOps culture.
Microservices architecture is popular for its enhanced scalability. As each service is distinct and separate, you can easily scale it without affecting other services. For example, if one service is experiencing a sudden uptick in demand, you can independently scale it without needing to scale the whole app. Such specific scaling is efficient and cost-effective, making microservices the ideal choice for companies that experience variable workloads.
Top 5 Design Patterns in Microservices
1. The API Gateway Pattern
Since each app service in microservices uses fine-grained APIs for communication, it becomes very challenging to manage each API separately. This is especially true if your application has scores or hundreds of microservices. But worry not; having a sound grasp of the API Gateway pattern helps your development team overcome this challenge.
The API Gateway design pattern acts as a single entry point for clients, simplifying requests and handling authentication, authorization, and load balancing. It can aggregate multiple microservices into a single unified API, making client interactions easier to manage. This reduces the number of client requests and minimizes latency.
However, you must be careful as this design pattern also has some downsides. For one, it can become a single point of failure unless you ensure that it is highly available. It can also lead to latency problems if you don’t design it properly.
Nevertheless, the API Gateway pattern, if designed properly and coupled with sound operational practices, is an excellent way for developers to make client interactions simpler.
2. The Circuit Breaker Pattern
The rise of microservices applications is composed of services that often have to depend on each other. This means that if one service’s performance is impacted adversely, all the other services that depend on it will also be affected. The Circuit Breaker pattern, as the name suggests, helps to mitigate such situations.
The Circuit Breaker pattern helps you prevent one service failure into a cascading failure that envelopes other dependent services. Whenever the application finds a failure, this design pattern trips the app and prevents any more calls to the failed service. Next, it proceeds to call the service at regular intervals. If these calls are successful, it opens the circuit and allows the service calls to go through.
The greatest advantage of this pattern is that it enables you to maintain app performance and steer clear of downtimes. However, you need to ensure proper tuning to balance sensitivity and responsiveness to service failure for the design pattern to work correctly. Even though you might consider this pattern complex, remember that it allows you to create a highly resilient application.
3. Database Per Service Pattern
Modules in a monolithic application typically use the same database. Such an approach may be easier to manage, but it causes tight coupling between the various app modules. This leads to difficulties in maintaining and scaling the app. That is where the Database Per Service design pattern comes into action.
The Database Per Service design pattern ensures high cohesion and loose coupling as each microservice has its own database. This allows you to scale every microservice independently.
However, the challenge with this design pattern is that you have to address distributed data management problems, such as ensuring data consistency for different services. Despite this challenge, the Database Per-service architectural design pattern helps you achieve autonomy and data isolation in microservices applications.
4. The Event-Driven Pattern
Maintaining and ensuring data consistency across services can be challenging in a microservices architecture. However, the Event-driven pattern has an answer to this problem as it promotes loose coupling between microservices by enabling them to communicate asynchronously through events.
In this architectural design, a service publishes an event whenever its state changes. Other services follow these events and subsequently update their states. This allows every service to maintain data consistency without requiring synchronous communication.
Therefore, the Event-driven pattern is an excellent architectural design pattern for decoupling services and improving performance via asynchronous communication. However, adopting the Event-driven pattern requires careful consideration of event schema evolution, event reliability, and message ordering.
5. The Saga Pattern
Handling distributed transactions across multiple microservices is another challenge of a microservices-based architecture. The Saga pattern is a powerful tool for managing the implementation of business transactions that use several microservices.
A saga represents a sequence of local transactions, each executed by an individual microservice, to accomplish a global transaction spanning multiple services. If an error occurs during the saga’s execution, it can trigger compensation actions to undo or correct the changes made by preceding transactions, thus ensuring data consistency.
A saga often has an orchestrator that coordinates the order of execution of the local transactions and handles error scenarios. The Saga pattern is suitable for scenarios where you require strict data consistency, but it comes with complexity and the need for careful design to handle failure scenarios.
Microservices design patterns play a crucial role in shaping the architecture and performance of a microservices-based system. Each pattern helps you resolve specific challenges and provides a set of advantages and complexities. The top five design patterns shared in this article are your best bet for building high-performance, scalable, and resilient microservices apps.
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