This document discusses microservices architecture as an alternative to monolithic architecture. It begins with an overview of monolithic architecture and its shortcomings such as difficulty scaling and maintaining code. Microservices aim to address these issues by breaking applications into independently deployable services. The document outlines microservices principles like organizing around business capabilities and decentralized data management. It also covers common microservices patterns and technologies like service discovery. Finally, it provides an example strategy for adopting microservices.

1. MicroServices
Intro
by alex apollonsky
manahealth

2. Agenda
● Monolithic Architecture
● Monolithic Architecture Shortcomings
● MicroServices to help
● MicroServices Principles
● MicroServices Design Patterns
● MicroServices Key Technologies
● MicroServices Adoption Strategy Example

3. Monolithic Service
Monolithic Architecture
● Large Server-Side Process providing complete domain functionality
● Exposes multiple x-domain endpoints
● Deployed as a single unit
● Can be horizontally scaled by running multiple instances
● Example:
Authentication Administration Data Access Data Updates ...
HTTP Endpoints
Transactional Database

4. Monolithic Architecture Shortcomings
● Can be deployed only as single unit
● Regression Testing of the complete service required after every change
● Difficult to maintain good modular structure as service grows
● Complexity and amount of Unit and Integration Tests
● Difficult to coordinate team (or multiple teams) working on the same service

5. MicroServices to Help
● Smaller Independently Deployable Services
● Each Service relies on its own persistence layer where possible
● Manageable Unit/Integration Tests
● Not locked in into single technology/language
● Scalable across multiple teams
Authentication Administration Data Access Data Updates ...
HTTP Endpoints
Transactional Database
Service Data Service Data Service Data Service Data Service Data

6. MicroServices Principles
● Organized around Business Capabilities (Domain-Driven Design)
● Deploy separately, deploy in Containers
● Smart Endpoints and Dumb Pipes
○ Queues/Topics used for data transfer, not intelligent routing
○ Services are smart enough to pickup/process their data
● Coarser-grained communication approach
○ Changing in-memory calls to RPC or messaging will make it too chatty
○ May need to aggregate service logic
● Decentralized Data Management
○ Use independent persistence layer where makes sense
● Design with Versioning in mind
● Follow Single Responsibility Principle
○ Gather those things which change for the same reason, Separate those things which change for
the different reason
● Beware of nano-services

7. MicroServices Design Patterns: Aggregator (Proxy)

8. MicroServices Design Patterns: Chained

9. MicroServices Design Patterns: Register/Discover
Service A
Service Registry
(router)
Service B
Register
Service
Discover
Service

10. MicroServices Key Technologies
Docker - Container
Kubernetes - Container Orchestration (deployment/management)
Docker Swarm - another Container Orchestration
Mesos/Marathon - yet another Container Orchestration
Rancher - Orchestration UI console

11. MicroServices Adoption Strategy Example
● Plan/POC deployment/CI infrastructure
● Create MicroServices Project Template
● Start new services as MicroServices
● Migrate existing monolithic services to MicroServices architecture in the
background (out of critical path)
Research/POC Deployment/CI
MicroService
Template
Create New
MicroServices
Migrate Existing
Services

12. References
● https://martinfowler.com/articles/microservices.html
● https://en.wikipedia.org/wiki/Microservices
● http://microservices.io/patterns/microservices.html