Synchronous communication

A simple solution for synchronous communication between services is to use REST and transfer JSON data over HTTP. REST can also help in service discovery by using Hypermedia as the Engine of Application State (HATEOAS). HATEOAS is a component of REST which models relationships between resources by using links. Once the client queries the entry point of the service, it can use the links it receives to navigate to other Microservices.

If text-based transfers are not desired, protocol buffers (Google's data interchange format) may be used to transmit data. This protocol has been implemented in several languages to increase its adoption, for example, Ruby protobuf.

A protocol that can be used to transmit structured data across a network is Simple Object Access Protocol (SOAP). It can be used to make calls to different Microservices using various transport mechanisms such as JMS, TCP, or UDP. SOAP is language-neutral and highly extensible.