07.Service Discovery | Eureka

 Service Discovery  | Eureka

In short, Service discovery is micro service calling technique.

In the microservices, microservices needs to talk each other.මෙහිදී එක microservice එකක් අනෙත් microservice එකත් සමග communicate කරන්නේ අනෙත් service එකේ IP:PORT හරහා.උදාහරණයක් ලෙස rest service එකක් call කරනවා කියලා හිතන්න.අපි මොකද කරන්නේ rest service එකේ IP:PORT එක හරහා එකට call කරලා data ගන්නවා. Microservices වලත් ඒ වැඩේ එහෙම්ම තමා.එත් URL hardcode කරලා call කරන්නේ නෑ පහත ප්‍රශ්න එන නිසා. 

01.Change require code update – URL එක වෙනස් වෙද්දී code එක update කරන්න සිද්ද වෙනවා.

02.Dynamic URL in the cloud – URL එක dynamically ව ලැබෙන්නේ AWS වගේ ඒවා පාවිච්ච් කරද්දී.

03.Load balancing-හිතන්න එකම microservice එකක instance 3ක් server 3 ක තියෙන්නේ කියලා.මෙවිට URL 3ක්  තියනවා.මෙවිට මොන URL එකද use කරන්නේ කියන එක ප්‍රශ්නයක්.එක URL එකක් දුන්නොත් අනෙත් ඒවා access කරනන් බැ.මෙවිට load balance කරන්නත් බැ.

04.Multiple environment – Development environment එක එකක්, QA environment එක වෙනත් එකක්, live environment එක වෙනත්ම එකක්.

As a solution for that, microservice වලදී service discovery යොදා ගනු ලබයි.Service Discovery is a pattern which is used to talk micro service each other.මෙය Service Discovery concept එක Eureka මගින් implement කර ඇත.

 

Service Discovery එක ආකාර දෙකකි.

01.Client side service discovery – Eureka වල බාවිතා වනුයේ මෙයයි.

02.Sever side service discovery

01.Client side service discovery

 

02.Sever side service discovery

Eureka

A technology which used to implement service discovery is Eureka. Eureka has been developed by Netflix OSS for spring boot. Netflix OSS is a leader to create micro service libraries. It created libraries as Eureka, Ribbon, Hystrix, Zuul.

Eureka service (Registry service) – this will register all the microservice, then client microservice will look up the eureka service to get depended microservice to get the job done.

Note:

What is an example of a pattern and technology? What is the difference?

Service discovery is a pattern when you have an application broken in to different services, how they have communicate with each other how do them discover whom to communicate with that service. Service discovery is a pattern and we have technologies which allow for that pattern you have Eureka is one technology. Those two works together. patterns which you have to do to make micro services work and you have these technology which are like 800 developers working on microservices are going to run same problem, Eureka is develop by somebody as a solution.