This article is excerpted from the AWS whitepaper, "Implementing Microservices on AWS"

Summary

Microservices are an architectural and organizational approach to software development that can accelerate deployment cycles, enhance innovation and autonomy, and improve the maintainability and scalability of software applications. By using agile methods, microservices help teams work independently and scale the software and services delivered by the organization. In the microservices approach, software is composed of small services that communicate through well-defined, independently deployable APIs. These services are owned by small autonomous teams. This organizational approach is key to successfully scaling organizations.

When customers build microservices, we observe three common patterns: API-driven, event-driven, and data streaming. In this article, we will introduce all three approaches, summarize the common characteristics of microservices, discuss the main challenges of building microservices, and describe how product teams can leverage Amazon Web Services (AWS) to overcome these challenges.

Introduction

Microservices architecture is not an entirely new approach to software engineering, but rather a combination of various successful and mature concepts, such as:

• Agile software development
• Service-oriented architectures
• API-first design
• Continuous Integration/Continuous Delivery (CI/CD)

Simple Microservices on AWS

Typical applications are built using different layers—user interface layer, business layer, and persistence layer. The core idea of microservices architecture is to split functionality into cohesive "vertical domains"—not by technical layers, but by implementing specific domains.

User Interface

Web applications typically use JavaScript frameworks to implement single-page applications that communicate with REST or RESTful APIs. Static web content can be served using Amazon Simple Storage Service (Amazon S3) and Amazon CloudFront.

Microservices

We often say that APIs are the gateway to microservices. An API acts as the entry point for application logic behind a set of programming interfaces (usually RESTful web service APIs).

Data Storage

Data storage is used to store the data needed by microservices. Popular session data stores are in-memory caches such as Memcached or Redis. AWS provides both technologies as part of the managed Amazon ElastiCache service.

Reducing Operational Complexity

The architecture we described already uses managed services, but we still need to manage Amazon Elastic Compute Cloud (Amazon EC2) instances. We can further reduce the operational work required to maintain and monitor microservices by using a fully serverless architecture.

Serverless Microservices

"No server is easier to manage than no server." Eliminating servers is a good way to eliminate operational complexity. Lambda integrates tightly with API Gateway. The ability to make synchronous calls from API Gateway to Lambda enables the creation of fully serverless applications.

Distributed System Components

After understanding how AWS addresses challenges related to individual microservices, we now want to focus on cross-service challenges, such as service discovery, data consistency, asynchronous communication, and distributed monitoring and auditing.

Service Discovery

One of the main challenges of microservices architecture is allowing services to discover and interact with each other. Amazon ECS now includes integrated service discovery, making it easier for your containerized services to discover and connect to each other.

Distributed Data Management

Monolithic applications are typically backed by a large relational database that defines a single data model common to all application components. In the microservices approach, this central database would hinder the goal of building decentralized and independent components. Each microservice component should have its own data persistence layer.

Asynchronous Communication and Lightweight Messaging

In traditional monolithic applications, communication is direct—parts of the application communicate with other parts using method calls or internal event dispatching mechanisms. If the same application is implemented using decoupled microservices, network communication must be used to implement communication between different parts of the application.

Distributed Monitoring

Microservices architecture consists of many different distributed components that need monitoring. You can use Amazon CloudWatch to collect and track metrics, centralize and monitor log files, set alarms, and automatically respond to changes in your AWS environment.

Conclusion

Microservices architecture is a distributed design approach aimed at overcoming the limitations of traditional monolithic architecture. Microservices help scale applications and organizations while improving cycle times. However, they also bring some challenges that may add extra architectural complexity and operational burden.

AWS provides a large number of managed services that can help product teams build microservices architecture and minimize architectural and operational complexity. This article will guide you through relevant AWS services and how to use AWS services to implement typical patterns such as service discovery or event sourcing.