How do you use the Camel REST DSL to expose and consume REST services?

The REST DSL is a domain-specific language layered on top of Camel HTTP transport components. It describes REST APIs in a declarative verb-and-path style. The underlying HTTP server is pluggable — Undertow, Jetty, Servlet, or Netty — chosen via restConfiguration().

public class OrderRestRoutes extends RouteBuilder {
    @Override
    public void configure() {
        restConfiguration()
            .component("undertow").host("0.0.0.0").port(8080);

        rest("/api/orders")
            .get("/{id}").produces("application/json")
                .to("direct:getOrder")
            .post("/").consumes("application/json")
                .type(OrderRequest.class)
                .to("direct:createOrder");

        from("direct:getOrder")
            .to("sql:SELECT * FROM orders WHERE id = :#${header.id}");
    }
}

// Consuming an external REST endpoint:
from("direct:callProducts")
    .to("rest:GET:/api/products?host=catalog.internal:8080");

REST DSL routes handle JSON/XML binding automatically when a type() class is specified. The rest: component acts as a producer for calling external REST APIs. Use camel-openapi-java to generate an OpenAPI spec from REST DSL definitions. In Spring Boot, auto-configure the REST engine via camel.rest.component=servlet.