Otavio Santana @otaviojava Mastering Microservices A guide to preventing chaos in your Java architecture member of KI group

Otavio Santana @otaviojava Staff Engineer ● Java Champion ● JCP-EC-EG-EGL ● Apache Committer ● Eclipse Committer ● Eclipse Project Leader ● Book and blog writer Speaker

Monolith

● Simple ● Easy to maintain ● Single application ● Less Operation complexity Monolith

“Given the importance of defining stable service boundaries, I feel that microservice architectures are often a bad choice for brand new products or startups” Should I use microservices? By Sam Newman A good start Database Business Logic

Deprecated? “Leadership set the direction of microservices without consideration for the challenges and state of our application. After evaluating it, we found that microservices weren’t a fit for us, and required significant compromises.” Why our team cancelled our move to microservices By Steve Lemon

Don’t follow the herd “Certainly, we always read great things about the microservices architectures implemented by companies like Netflix or Amazon. So let me ask a question: how many companies in the world can be Netflix and Amazon?” Migrating to Microservices Databases By Edson Yanaga

● Conway's law ● Two-Pizza Team Rule ● Deploy Process Team

● More complex ● Operations complexity ● SAGA ● Minimum requirement Microservices

“Microservices introduce eventual consistency issues because of their laudable insistence on decentralized data management. With a monolith, you can update a bunch of things together in a single transaction. Microservices require multiple resources to update, and distributed transactions are frowned on (for good reason). So now, developers need to be aware of consistency issues, and figure out how to detect when things are out of sync before doing anything the code will regret.” Microservice By Martin Fowler Complexity

“We also address the critically important issue of trade-off analysis. As a software developer, it's easy to become enamored with a particular technology or approach. But architects must always soberly assess the good, bad, and ugly of every choice, and virtually nothing in the real world offers a convenient binary choice - everything is a trade-off.” Everything is a trade-off

Old but gold

“Microservices are independently deployable services modeled around a business domain. They communicate with each other via networks, and as an architecture choice offer many options for solving the problems you may face.” Moving to Microservices

API

1. API Design 2. Glory of Rest 3. Documentation 4. Versioning 5. DDD 6. Clean Architecture 7. Database 8. CQRS 9. Pagination 10. Security The 10 commandments Roan Brasil @roanbrasil

API design + API + Contract First + Contract Last 1 of 10

Glory of Rest 2 of 10 + Level 0 ○ HTTP - transport system for remote interactions + Level 1 ○ Individual resources + Level 2 ○ POST ○ GET ○ DELETE ○ PATCH/PUT + Level 3 ○ HATEOAS (Hypertext As The Engine Of Application State)

Documentation + Swagger + Language Documentation + Open-API 3 of 10

Versioning 4 of 10 + URL ○ http://yourapi.domain.com/api/v1/doSomething + Query Parameters ○ http://yourapi.domain.com/api/doSomething?version=1 + Custom Headers ○ Accept-version: v1 + Content Negotiation ○ Accept: application/vnd.domain.v1+json ○ Accept: application/vnd.domain+json;version=1.0

DDD + Ubiquitous Language + Domain + Subdomain + Bounded Context 5 of 10

Clean architecture 6 of 10 SOLID Layers + Presentation Layer ○ Controller + Application Layer ○ Service Orchestrating + Domain Layer ○ DTO/POJO ○ Entities ○ Services + Infrastructure Layer ○ Repositories ○ Config

Database + NoSQL vs SQL + Encapsulation + CAP 7 of 10

CQRS Command Query Responsibility Segregation + Greg Young's 2010 essay + Write - Command + Read - Query 8 of 10

Pagination + Performance + HATEOAS 9 of 10

Security Basic Authentication OAuth 2.0 + JWT - JSON Web Tokens (RFC 7519) ○ JWS - JSON Web Signature (RFC 7515) ○ JWE - JSON Web Encryption (RFC 7516) Site: https://jwt.io/ 10 of 10

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