As microservices – especially in contect of DevOps – will require frequently updates and elasticity, the usage of a service registry is highly required. The registry can also provide load balancing functionality for all given service instances. Client services can contact the registry to receive a service instance and call the correlated service instance afterwards:
Services therefore need to register at the registry; and re-register within intervals. This is required for failure cases. By registering also features can be controlled, such as service versions, SLA checkup, etc. Possible protocols for such registries can be any remote communication protocol, such as:
- HTTP
- RPC
- SOAP
- REST
- etc.