How to configure HTTP Service Clients with Protobuf in Spring Boot 4?

In the HTTP interface, declare that you want to send and receive protobuf:

import static org.springframework.http.MediaType.APPLICATION_PROTOBUF_VALUE; import org.springframework.web.bind.annotation.RequestBody; import org.springframework.web.service.annotation.PutExchange; public interface SomeBackendApi { @PutExchange( value = "/endpoint", contentType = APPLICATION_PROTOBUF_VALUE, accept = APPLICATION_PROTOBUF_VALUE) ProtobufResponseObject doSomething(@RequestBody ProtobufRequestObject request); }

Create a configuration class where you configure the ProtobufHttpMessageConverter for the http client:

import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.http.converter.protobuf.ProtobufHttpMessageConverter; import org.springframework.web.client.support.RestClientHttpServiceGroupConfigurer; import org.springframework.web.service.registry.ImportHttpServices; @Configuration(proxyBeanMethods = false) @ImportHttpServices(group = "some-backend", types = SomeBackendApi.class) public class SomeBackendConfiguration { @Bean public RestClientHttpServiceGroupConfigurer groupConfigurer() { return groups -> groups .filterByName("some-backend") .forEachClient( (group, clientBuilder) -> clientBuilder.configureMessageConverters( it -> it.addCustomConverter(new ProtobufHttpMessageConverter()))); } }

You can now inject an instance of SomeBackendApi into any other Spring bean and call its method(s) to do a remote call using Protobuf.