Cloud / Microservices / DevOps

Architecture Considerationso Strategic Goals and Visiono Architectural Principles to guide developmento Defining boundaries of modules / microservices

Declaring a bounded context Chattiness / coupling Expressiveness of model Feature roadmap

o Design and Delivery Practices Required Standards Monitoring Interfaces Architectural Safety Reusable Service Archetypes / Code Libraries

o Iteration – redoing code to become more elegant, vs. striving for a perfect solution from the start. Not to be confused with slicing, as in Agile.

Cloudo Programmable infrastructure that you can introspect and make strong

assertions abouto On-demand capacityo Built on commodity hardware/softwareo Competition between cloud platforms is driving down cost

Penalty of lock-in is outweighed by cost reduction curve

Service Design Best Practiceso Loose Couplingo High Cohesiono Bounded Contextso Single-Responsibility Principleo Stateless to support horizontal scalabilityo Hide implementation details

Service Integrationo Technology-agnostic APIs

JSON / XML Protocol Buffers REST and HATEOAS

Spring abstractionso Request/Response vs. Asynchronous Event-Based Communication

Choreographed architecture preferred over Orchestration Inform each part of the system through message bus

o Versioning Semantic Versioning (MAJOR, MINOR, PATCH) Version in endpoint URL Version in request header

o API Gateways

Portability layer for forwards/backwards compatibilityo Strangler Pattern

Abstraction layer on top of legacy systemso Discovery and Coordination

Netflix Eureka Optimized for AWS Placed behind AWS ELB Mid-tier round-robin load balancer Optional Sidecar for non-JVM apps

Consul DNS ZooKeeper Metadata in AWS

Testingo Unit Tests / TDD

Spocko Service Tests – Mock/Stub downstream collaboratorso Consumer-Driven Testso End-to-End Testso Testing in Production

Blue/Green Deployment Canary Releases Rolling Upgrades A/B Testing

Indeed Proctor Feature Toggles

o MTBF / MTTR

Deploymento Continuous Integrationo Build Pipelineo Images as Artifacts / Immutable Servers

Docker containers Spin up new instance instead of modifying existing. “Cattle” vs. “Pet” servers Ephemeral infrastructure

o Environment Definitionso Rollout Plano Rollback Plan

Logging of audit metadata to reverse actionso AWS CloudFormation

Securityo SSO Gateway / Identity Providero Service-to-Service Auth.

oAuth 2.0 / JSON Web Token (JWT) Network Segmentation HTTP(S) Basic

X.509 API Keys

o Multi-tenancyo Concerns

Man-in-the-Middle attack Confused Deputy Problem

Scalingo Circuit Breakerso Bulkheadso Idempotencyo Immutable Data Structureso Load Balancingo Worker-based systemso Data Access Strategies

Scaling for reads Scaling for writes Caching CQRS / Event Sourcing

Explicitly modeling events and state change Derive current state from series of events Actor model

o CAP Theorem Sacrificing Consistency Sacrificing Availability Sacrificing Partition Tolerance

Monitoringo Failure Detectiono Performance Degradation Detection

Latency Throughput Utilization

o Capacity Planningo User Interactiono Intrusion Detectiono Process Miningo Tools

Icinga / Nagios Graphite / Grafana Logstash Splunk / ElasticSearch AWS CloudWatch

Netflix Architectureo Disk inside EC2 instanceso Triple-replicated Cassandrao Ribbon/Karyono Eureka instance in each availability zone

ZooKeeper “too consistent” API versioning

o Hystrix circuit breakerso Customer-facing apps optimized for ‘AP’o Business apps optimized for ‘CA’o Security Monkey

NoSQL - “Not only SQL”o Cassandrao MongoDBo Couchbaseo Neo4j