Service Registration & Service Discovery


What is it?

Service Registration: Process of registering a service location in a central registry
Service Discovery: Process of client applications to query the central registry to find a service

What is it used for?

Locating services in:

  • Distributed environments
  • Service oriented architectures

Different Aspects of Services Discovery

Monitoring: Checking if a registered service is alive and kicking (heartbeat)
Load Balancing: Distribute load to different instances of the service
Versioning: Allow registration of the same service with different versions
Migration: Services will coexist with different versions to ease migration efforts
Availability: Resilient services to compensate lost nodes

Intershop Cloud & Service Discovery

We do not need Service Discovery!

  • Application Servers know each other via multicast
  • Web Adapter knows about Application Servers via ConfigurationServlet
  • Application Server knows about Solr via Managed Service configuration
  • Services plugged-in into Managed Service Framework and configured via same

So why do we implement a Service Discovery then?

  • Services in the cloud have dynamic IP’s, are spread over different regions
  • Configuration on the fly is a problem as of now in Intershop
  • Real Time Monitoring needs to know about all running services
  • Strategic importance for discovering Microservices
  • Version Management
  • Load Balancing
  • Security
  • Clustering

Which tools did we consider?


  • Open Source
  • Java project from Netflix
  • REST based service primarily for AWS
  • Point-to-Point Client/Server communication
  • Key/Value Store for Metadata
  • Health check included
  • Netflix is using Eureka
  • Eureka is integrated into Spring
  • Newest version Eureka 1.4.7


  • Open Source
  • Go project by HashiCorp
  • Based on Gossip protocol Serf
  • Communication relies on TCP and UDP unicast
  • Key/Value Store for Metadata
  • Health check included
  • is using Consul
  • Newest version Consul 0.6.4


  • Open Source
  • Java project maintained by Apache
  • Subproject of Apache Hadoop, now it’s own top-level project
  • Data is stored in a hierarchical name space
  • Atomic messaging system between server to keep them in sync
  • Quorum is used to distribute and retrieve information
  • Apache Solr, Apache HBase, Apache Hadoop are using ZooKeeper
  • Netflix was using ZooKeeper up until they decided to write their own tool
  • Newest version ZooKeeper 3.4.8

And now a short detour into theoretical computer science – the CAP theorem:

Eric Brewer, University of California, Berkley:

  • Consistency: All nodes see the same data any time
  • Availability: All requests receiving a response
  • Partition Tolerance: System is continuing to operate despite arbitrary partitioning due to network failures

A distributed system can satisfy any two for instance Availability and Partition Tolerance (AP) or Consistency and Partition Tolerance (CP) of these guarantees at the same time but not all three!

Decision Matrix

Eureka Consul ZooKeeper
Classification CAP AP CP CP
Java Client Lib exists? Yes Yes Yes
OS Support Windows, Linux Windows, Linux Windows, Linux
Cloud Support Amazon Webservices
Microsoft Azure
Amazon Webservices
Microsoft Azure
Amazon Webservices
Microsoft Azure
Maturity ++ + +++
Community +++ + +++
Discovery Client-side Client-side Client-side
Deployment Tool Netflix Asgard Atlas
Dynamic Routing/Load Balancing Netflix Ribbon
Circuit Breaker Netflix Hystrix
Monitoring Netflix Hystrix, Netflix Turbine
Edge Server Netflix Zuul
Client Development Tool Netflix Feign

And the Winner is … Eureka

Why did we choose Eureka?

  • Uses AP over CP
  • Strong Tooling around Service Discovery

Why did we rule out Consul?

  • Not mature enough
  • Uses CP over AP

Why did we rule out ZooKeeper?

  • Uses CP over AP

Cool thing you might say.

But when is it available?

Our Service Registration & Service Discovery (SRD) will be available with Intershop Commerce Management For those who don’t wanna use Eureka it is possible of course to do their own implementation with any other SRD out there which works similar to the one we investigated.

For instance in a Hackathon, which takes place every 6 months, we demonstrated within 3 days of work a prototype which used Consul instead of Eureka.

Service Registration & Service Discovery
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