Microservices & Spring RESTBuilding applications for the cloud Tech Talks

Agenda

• What are Microservices?

• What are not Microservices?

• REST Services

• Build REST Services with Spring

• Questions and Answers

215 May 2015

What is for you Microservices?

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

What is not for you microservices?

What is not Microservices?

• Monolithic• Layered Cross-Functional• Intelligently integrated• Centrally integrated

615 May 2015

Monolithic -> SOA -> Microservices

• SOA is too coarse-grained, Microservices is fine-grained and practical SOA.

715 May 2015

Monolith vs Microservices

Monolith Microservice

Simplicity Partial deployment

Consistency Availability

Inter-modular refactoring Real Modular

Technology constraints Multiple platforms

815 May 2015

Microservice Benefits

• Autonomy of the team• Ownership• Speed of change• Scalability• Elasticity• Innovation• Tech diversification• Less code, more value

915 May 2015

Microservices Hidden Costs

• Network latency• Network reliability• Packet lost• Bandwidth• Security• Testing is more complicated• DevOps

1015 May 2015

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

MicroservicesStructural 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

• 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

MicroservicesStructural principles

1315 May 2015

• 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

MicroservicesStructural principles

1415 May 2015

MicroservicesStructural 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

MicroservicesOperational 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

MicroservicesOperational 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

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

Microservices Patterns• Fault tolerant, design for failure • Abstraction layer• One service at a time• Health Check• Stateless

1915 May 2015

Anti-Patterns

• Complex configuration• Complicated dependencies• Managed shared state

2015 May 2015

MicroservicesThings 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

• 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

MicroservicesThings to remember

2215 May 2015

MicroservicesThings to remember

2315 May 2015

Componentization via REST Services

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

Status codes

• 1xx: informational • 2xx: success • 3xx: redirection • 4xx: client error • 5xx: server error

2615 May 2015

REST Practices*

• Good HTTP Headers• Idempotent• Link and navigational• JSON

• *For VCS poject

2715 May 2015

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

Demo

• Hello REST Service• Monitoring Services• Unit Test for REST Services

2915 May 2015

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

Questions?Thank you!