microservice architecture

Microservice Architecture

Engin Yyen

November, 2014

What is a microservice?

is a small, discrete, isolated, lightweight application that is stateless service and can be deployed separately.

What is a monolith?

is a single unit of application, which all the business logic and data access code are combined into a single application.

Microservice vs Monolith?

Call Center Agents : Current available agents

Calls : Current calls with details such customer, length of call, agent

Statistics : Current number of calls per day

Monitoring : Failing calls, connections, etc.

This is how does it look like!

And this is how you scale!

of course, more work involved!

ComparisonMonolith Microservice

Update and Feature Delivery

new features takes time to implement

easy to understand easy to implement

Deployment not frequent but easyfrequent but

orchestration can be challanging

Isolation errors can have effect on entire systemerror has effect only on

particular services

Response Time Process call (Faster) API Call (Slower)

Comparison (2)Monolith Microservice

New DevelopersLong learning curve

(understanding application)

Long learning curve (understanding

architecture)

Technology Standardization on single technologyChoice of technology

based on problem

Testing Relatively Simple Complexity of distributed systems

Development Tools (IDE)

Larger the code base slower the IDE gets Not an issue

Characteristics of Microservice Architecture

Single Responsibility Single Responsibility Principle : Do one thing, but

do it well

a responsibility = a reason for change

How small is small? Size does not matter!

Line of code(LOC) is not a good measurement, depends on language, on developer.

Stateless

Each request as an independent transaction

Persist your data!

Data Management

Data ManagementEach service can have its own data store, and it can be different technology

Communication between services

HTTP (Request, Response)

Message Queue (e.g. RabbitMQ, zeroMQ )

Dont Reinvent The Wheel. Use

HTTP Status Code

HTTP Headers

REST (Not just the url also the body)

Deployment Each service has its own

Repository

Build Pipeline

Host

Build single artifact that represent release candidate. Do not build artifact for different environment

Manage configuration separately

Can we provision a server less than 1 minute?

Deployment

Source : http://www.slideshare.net/fasgoncalves/hypervisor-versus-linux-containers

Deployment : Image Management

Source : https://www.joyent.com/developers/image-management/

IT Configuration and Automation

Dont do anything manually on any of your servers

Good understanding of IT Automation and tools (e.g. Ansible, Chef, Salt, Puppet)

Flexibility to build and deploy new services

You Build It, You Run It!

Testing

Source : http://lisacrispin.com/2011/11/08/using-the-agile-testing-quadrants/

Test different scope, for different purposes

Higher the pyramid, shorter the feedback cycle

End-to-End tests are not easy for microservices Team structure, who writes the test Testing multiple microservices Network issues, time-to-complete

Testing

Source : http://www.thoughtworks.com/insights/blog/introducing-software-testing-cupcake-anti-pattern

Monitoring Monitor your host and individual services

Check health of your system

Keep track of your logs

Build and use conventions (e.g. Standardise your logs)

Use existing tools: ElasticSearch, Kibana, Graphite, Logstash,

Metrics

Response time

Error Rate

Correlation ID

The Company Culture

Decentralized Governance: Right tool for right job

Open enough to change and adopt

Cross functional teams (e.g. for testing, operations)

Questions