Microservices with Spring
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This document discusses microservices and provides an overview of related concepts. It begins with definitions of microservices and comparisons to monolithic applications. Key features of microservices like independent processes communicating over HTTP are outlined. The document then covers reasons for using HTTP, REST, and JSON in microservice architectures. An example online shopping application is used to illustrate how it could be decomposed into microservices. Challenges of monolithic applications are contrasted with advantages of the microservice approach. The document concludes with a summary of Spring Cloud which provides tools to help implement microservices patterns.
Microservices with Spring
- 1. Microservices with Spring Cloud Kasim Sert 2016 1
- 2. 2 Agenda ๏ The Definitions ๏ Monolith vs Micro-Service ๏ Microservices Features ๏ Why HTTP,REST,JSON ? ๏ Case Study ๏ Demos ๏ Conclusion
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- 4. What are Microservices ? ๏ Decomposition of single system into a suite of small services each running as independent processes and intercommunicating via well known protocols 4
- 5. What are Microservices ? ๏ Decomposition of single system into a suite of small services each running as independent processes and intercommunicating via well known protocols ๏ Developing a single application as a suite of small services each running its own process and communicating with lightweight mechanisms often an HTTP resource API, Martin Fowler 5
- 6. What are Microservices ? ๏ Decomposition of single system into a suite of small services each running as independent processes and intercommunicating via well known protocols ๏ Developing a single application as a suite of small services each running its own process and communicating with lightweight mechanisms often an HTTP resource API, Martin Fowler ๏Fine-Grained SOA, Adrian Cockcroft-Netflix 6
- 7. Microservices Features ๏ Composing a single application using small services ๏rather than a single monolithic application ๏ each running as independent processes ๏not just modules in a single executable ๏ intercommunicating via open protocols ๏HTTP/Rest,or Messaging ๏ Separately written deployed scaled and maintained ๏potentially in different languages ๏ Services are independently replaceable and upgradable 7
- 8. Microservices Are Not ๏ SOA ๏SOA is about integrating enterprise applications, Microservices are about decomposing single applications ๏ A Silver Bullet ๏Microservices approach involves drawbacks and risks ๏ New! 8
- 9. Microservices Are Trending ๏ Twitter moved from Ruby/Rails monolith to Microservices ๏ Facebook moved from PHP monolith to Microservices ๏ Netflix moved from Java monolith to Microservices 9
- 10. Benefits of a Microservice Approach ๏ Extreme Scalability ๏ Organisational Ownership ๏ Cheaper to Start ๏ Ideal for the Cloud ๏ Grasp latest technologies ๏ Promotes Agile Practices ๏ Promotes DevOps ๏ “It’s what the cool people do!” 10
- 11. Benefits of a Monolith ๏ Common code infrastructure ๏ More density/efficient allocation of hardware ๏ Less inter-process communication required, less network hops ๏ Easy to scale(up to some level with load balancer) ๏ Easy to test as a single unit(up to some limit) 11
- 13. HTTP ๏ Available verbs GET, POST, PUT, DELETE (and more) ๏ Mechanisms for • caching and cache control • content negotiation • session management • user agent and server identification ๏ Status codes in response (200, 404, etc) for information, success, redirection, client error, server error ๏ Rich standardised interface for interacting over the net 13
- 14. JSON ๏ Minimal and popular data representation format ๏ Schemaless in principle, but can be validated if needed 14
- 15. REST ๏ Uniform Interface By; • Use of known HTTP verbs for manipulating resources • Resource manipulation through representations which separated from internal representations • Hypermedia as the engine of application state (HATEOAS): Response contains all allowed operations and the resource identifiers needed to trigger them 15
- 16. Case Study ๏ Consider Monolithic Online Shopping Application ๏Web/Mobile Interfaces ๏Functions for: ๏Searching for products ๏Product catalog ๏Inventory management ๏Shopping cart ๏Checkout ๏Order Fulfilment ๏How would this look with microservices? 16
- 17. Basic Diagram 17
- 19. New Types of Client 19
- 20. New Types of Persistence/ Services 20
- 21. Monolith Challenges ๏ Language/Framework Lock ๏ Digestion ๏Single developer can not digest ๏Single team can not manage a large application(amazon’s 2 pizza rule) ๏ Deployment as single unit ๏Can not independently deploy single change (risky) ๏Ready changes should be wait(next deploy) 21
- 22. Case Study with Microservices 22
- 23. Microservices Advantages ๏ Encapsulate Business capabilities ๏ Not dependent on technology stack ๏ Easy to digest each service ๏ Easy to test, deploy manage, version and scale each service. ๏ Changes can be deployed as soon as ready 23
- 24. Microservices Disadvantages ๏ Complexity moved to operation layer ๏fallacies of distributed computing ๏ Services will be unavailable ๏Design for failure ๏Much more need for monitoring(Healthcheck?) ๏ Remote Calls more expensive than in-process calls ๏ Problem of Transactions (Eventual consistency over ACID) ๏ Features span multiple services (Hard to Integration Test) 24
- 25. Fallacies of Distributed Computing ๏ Network is reliable ๏ Latency is zero ๏ Bandwith is infinite ๏ The Network is secure ๏ Topology does not change ๏ There is one administrator ๏ Transport cost is zero ๏ The network is homogenous 25
- 26. Spring Cloud Summary ๏ Spring cloud(Using Netflix OSS internally) ๏Apply common patterns needed in distributed/cloud applications ๏Distributed/Versioned/Centralised Config. Management ๏Service Registration/Discovery ๏Load Balancing ๏Circuit Brakers ๏Monitoring ๏Based on Spring Boot 26
- 27. Spring Cloud Summary ๏ Spring Boot Stand-alone, production-grade Spring-based applications ๏ Spring Data REST / Spring HATEOAS Spring-based applications following HATEOAS principles ๏ Spring Cloud Config Centralised external configuration management, backed by Git ๏ Netflix Eureka REST-based service discovery and registration for failover and load-balancing ๏ Netflix Ribbon IPC library with built-in client-side software load-balancers ๏ Netflix Hystrix Latency and fault tolerance for distributed system ๏ Netflix Hystrix Dashboard Web-based UI for monitoring Hystrix 27
- 28. Netflix ๏ Reinvented itself in 2007 ๏ Moved from DVD mailing to video-on-demand ๏Once USPS biggest customer ๏Now biggest source of Internet Traffic ๏ Became pioneer in Cloud computing ๏since all applications run on AWS ๏ Open sources its cloud projects with name Netflix Open Source Software 28
- 29. Conclusion ๏ Monoliths always bad? ๏ How micro is micro? ๏Small enough for one developer to digest ๏Predictable and easy to experiment ๏If necessary can be rewritten in different technology stack in two weeks 29
- 33. References ๏ https://en.wikipedia.org/wiki/Microservices ๏ http://martinfowler.com/articles/microservices.html ๏ https://start.spring.io ๏ https://projects.spring.io/spring-cloud/ 33
- 34. Questions? 34