Basic concepts about Microservices

1. Microservices & Spring REST
Building applications for the cloud
Tech Talks

2. Agenda
• What are Microservices?
• What are not Microservices?
• REST Services
• Build REST Services with Spring
• Questions and Answers
215 May 2015

3. What is for you
Microservices?

4. What is Microservices?
• It is an approach to developing a single application as a suite of
small services, each running in its own process and communicating
with lightweight mechanisms, often an HTTP resource API
• Fine-grained domain capability
• Independently deployable
• Independently releasable
• Language, data storage and technologies agnostic
• Designed for the Cloud
415 May 2015

5. What is not for you
microservices?

6. What is not Microservices?
• Monolithic
• Layered Cross-Functional
• Intelligently integrated
• Centrally integrated
615 May 2015

7. Monolithic -> SOA -> Microservices
• SOA is too coarse-grained, Microservices is fine-grained and
practical SOA.
715 May 2015

8. Monolith vs Microservices
Monolith Microservice
Simplicity Partial deployment
Consistency Availability
Inter-modular refactoring Real Modular
Technology constraints Multiple platforms
815 May 2015

9. Microservice Benefits
• Autonomy of the team
• Ownership
• Speed of change
• Scalability
• Elasticity
• Innovation
• Tech diversification
• Less code, more value
915 May 2015

10. Microservices Hidden Costs
• Network latency
• Network reliability
• Packet lost
• Bandwidth
• Security
• Testing is more complicated
• DevOps
1015 May 2015

11. Microservices Complexity
• Communication
– Better documentation
– Fan customer empathy
• Execution
– Continuous deployment and delivery
• Resilience
– Stateless Docker Containers
• Maintenance
– Backward compatibility
• Operational
– Easy usability
1115 May 2015

12. Microservices
Structural principles
• Resilient to failure
– Resiliency is designed into the application, rather than wrapped around it
after the fact. Failures in cloud infrastructure are handled fluidly without
interruption of service.
• Resilient to latency
– Applications adapt gracefully to latency rather than timing out/failing. High
• Secure
– Applications are based on secure lifecycle standards and include built-in
security
– Data at rest and in transit is encrypted. APIs are protected by authentication
and authorization.
1215 May 2015

13. • Location independent
– Applications discover services dynamically rather than relying on hard-coded
dependencies
• Elastically scalable
– Applications respond to demand levels, growing and shrinking as required, in
and among clouds
• SOA/Compose-ability
– Applications consume and expose web services with APIs discoverable at
runtime. The structure incorporates small, stateless components designed to
scale out
Microservices
Structural principles
1315 May 2015

14. • Designed for manageability
– Applications are instrumented and expose metrics and management
interfaces
• Infrastructure independent
– Applications make no assumptions about the underlying infrastructure, using
abstractions in relation to the operating system, file system, database, and so
on
• Defined tenancy
– Each application should have a deliberate, defined single tenancy or
multitenancy model
Microservices
Structural principles
1415 May 2015

15. Microservices
Structural principles
• Available end-user self-service
– Users should be able to register themselves to use the app through a self-
service registration interface, without entering an IT service request
• Bandwidth aware
– APIs and application protocols are designed to minimize bandwidth
consumption
• Cost and resource consumption aware
– Application architecture is designed to minimize costs due to bandwidth,
CPU, storage consumption, and I/O requests
1515 May 2015

16. Microservices
Operational strategies
• Ensure redundancy
– Applications are designed to be resilent to failure though the use of
redundancy. High
• Utilize caching
– Caching is used to improve performance, increase resiliency, and reduce
bandwidth costs. High
• Secure access to APIs
– API end points are protected via API Management gateways. High
• Stage deployments
– The risk of failure due to deployment is reduced by staging the introduction of
updates to components of an application. Medium
1615 May 2015

17. Microservices
Operational strategies
• 5 Plan for zone/ region failures
– Applications are deployed in a way that is resilient to disasters, such as entire
geographic zone or region failures
• Minimize inter-zone/ region latency
– Applications are deployed geographically to minimize network latency
• Locate high-bandwidth consumers externally
– High bandwidth consumers are hosted outside the cloud to reduce cloud
bandwidth utilization costs
• Abstract dependencies
– API abstractions are used to prevent lock-in with proprietary cloud services
1715 May 2015

18. Microservices
Patterns
• Very, very small
• Loosely coupled ( including flow)
• Versioning
• Backward compatibility
• Blue/Green deployments
• Toggle features
• Continuous delivery
• Convention over Configuration
• Service Discovery Service
• Monitoring
• Correlation IDs
1815 May 2015

19. Microservices
Patterns
• Fault tolerant, design for failure
• Abstraction layer
• One service at a time
• Health Check
• Stateless
1915 May 2015

20. Anti-Patterns
• Complex configuration
• Complicated dependencies
• Managed shared state
2015 May 2015

21. Microservices
Things to remember
• Prepare for failure
– Fail fast and cheap
• Every integration point will eventually fail in some way, and you
need to be prepared for that failure.
• Do defensive programming
– Defend with timeouts
– Defend from thread deadlocks
– Defend from resources bottleneck
• Be lazy for programming,
• Do not rely in others code
• Communicate
– Commits and early integration is the best way to communicate
• Stress interfaces
• Slow responses are not an option
2115 May 2015

22. • Keep in mind the SLAs and strict performance requirements
• Use data replication and sharding
• Put limits
– Pagination, timeouts, big request, etc
• Use queues and asynchronous for those flows that allow it
• Verify integration point early
• Use health checks
• Avoid mocks
• Learn, learn and learn
Microservices
Things to remember
2215 May 2015

23. Microservices
Things to remember
2315 May 2015

24. Componentization via
REST Services

25. REST Services
• REST has no hard and fast rules
• REST is an architectural style, not a standard
• REST uses Headers to describe requests & responses
• REST embraces HTTP verbs
2515 May 2015

26. Status codes
• 1xx: informational
• 2xx: success
• 3xx: redirection
• 4xx: client error
• 5xx: server error
2615 May 2015

27. REST Practices*
• Good HTTP Headers
• Idempotent
• Link and navigational
• JSON
• *For VCS poject
2715 May 2015

28. How to build a REST service
1
2
3
4
• Create REST Controller
• Annotate with Request Mapping
• Build the response
• Deploy REST Service
2815 May 2015

29. Demo
• Hello REST Service
• Monitoring Services
• Unit Test for REST Services
2915 May 2015

30. Resources
• OPEN DATA CENTER ALLIANCE Best Practices: Architecting Cloud-
Aware Applications Rev. 1.0
• http://www.infoq.com/presentations/Netflix-Architecture
• http://martinfowler.com/articles/microservices.html
• Release It!: Design and Deploy Production-Ready Software Book
• https://spring.io/guides/gs/rest-service/
• https://www.youtube.com/watch?v=wgdBVIX9ifA
3015 May 2015

31. Questions?
Thank you!