REST is a dominant communication style used in SOAs. The business domain model is exposed as resources, where each resource is a published web service that has a defined API contract. These APIs take input using a message format such as JSON and share a response compliant to the protocol used. The microservice itself will have additional external dependencies, such as other APIs for which it acts as the REST client. Since the communication is over the network, it adds to the latency of a service call and thus it's vital to keep this communication lightweight. Each service would also need to be resilient to failures in other services.
To deal with failures and performance issues in other services, a service may incorporate strategies to overcome such cases. As an example, a users service may invoke the tickets API/resource for fetching the latest tickets...