<dependency> <groupId>org.apache.cxf</groupId> <artifactId>cxf-rt-rs-client</artifactId> <version>3.0.15</version> </dependency> In CXF 2.7.x no JAX-RS 2.0 Client API is supported and CXF specific Client API is located in the cxf-rt-frontend-jaxrs module. CXF Apache HttpClient based transport is required to get the asynchronous invocations working correctly: <dependency> <groupId>org.apache.cxf</g