Microservice Architecture

"Microservices are a software development technique—a variant of the service-oriented architecture (SOA) architectural style that structures an application as a collection of loosely coupled services. In a microservices architecture, services are fine-grained and the protocols are lightweight. The benefit of decomposing an application into different smaller services is that it improves modularity. This makes the application easier to understand, develop, test, and become more resilient to architecture erosion. It parallelizes development by enabling small autonomous teams to develop, deploy and scale their respective services independently. It also allows the architecture of an individual service to emerge through continuous refactoring. Microservices-based architectures enable continuous delivery and deployment."

— Wikipedia

Introduction

One of the major goals of the ABP framework is to provide a convenient infrastructure to create microservice solutions. To make this possible,

• Provides a module system that allows you to split your application into modules where each module may have its own database, entities, services, APIs, UI components/pages... etc.
• Offers an architectural model to develop your modules to be compatible to microservice development and deployment.
• Provides best practices guide to develop your module standards-compliance.
• Provides base infrastructure to implement Domain Driven Design in your microservices.
• Provide services to automatically create REST-style APIs from your application services.
• Provide services to automatically create C# API clients that makes easy to consume your services from another service/application.
• Provides a distributed event bus to communicate your services.
• Provides many other services to make your daily development easier.

Microservice for New Applications

One common advise to start a new solution is always to start with a monolith, keep it modular and split into microservices once the monolith becomes a problem. This makes your progress fast in the beginning especially if your team is small and you don't want to deal with challenges of the microservice architecture.

However, developing such a well-modular application can be a problem since it is hard to keep modules isolated from each other as you would do it for microservices (see Stefan Tilkov's article about that). Microservice architecture naturally forces you to develop well isolated services, but in a modular monolithic application it's easy to tight couple modules to each other and design weak module boundaries and API contracts.

ABP can help you in that point by offering a microservice-compatible, strict module architecture where your module is split into multiple layers/projects and developed in its own VS solution completely isolated and independent from other modules. Such a developed module is a natural microservice yet it can be easily plugged-in a monolithic application. See the module development best practice guide that offers a microservice-first module design. All standard ABP modules are developed based on this guide. So, you can use these modules by embedding into your monolithic solution or deploy them separately and use via remote APIs. They can share a single database or can have their own database based on your simple configuration.

Microservice Demo Solution: eShopOnAbp

The eShopOnAbp project demonstrates a complete microservice solution based on the ABP framework.