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Problem returning stream of responses from gRPC service to RESTful client

由 天涯浪子 提交于 2020-01-05 06:59:10

问题


I am attempting to write a set of services that will provide a REST interface to external clients, while using gRPC/protobuf for inter-service communication internally. Spring Boot is being utilized to help with the background infrastructure support. I only started learning and working with Google protobuf and gRPC about a week ago.

I have been able to successfully get simpler processing to work from end-to-end, but these are returning a single object (i.e. no streaming). I'm having a problem with a call that is intended to stream a collection of response objects. The other thing to note is that everything I have attempted so far have been GET requests.

The samples below just show the relevant portions that I'm having trouble with.

Details:

  • Java 8
  • Spring Boot 2.1.6.RELEASE
  • Spring Boot gRPC starter 2.5.1.RELEASE (https://yidongnan.github.io/grpc-spring-boot-starter/)
  • Google protobuf Java util 3.10.0

Protobuf definitions:

syntax = "proto3";

package experiment;

message BOM {
    PartSpec part_spec = 1;
    string description = 2;
    string category = 3;
}

message PartSpec {
    string part_number = 1;
    string cage_code = 2;
}

service BOMService {
    rpc getBOMList(google.protobuf.Empty) returns (stream BOM) {}
}

"Domain" service:

Implements the service defined by the .proto file. Responds to requests from the "gateway" service.

@GrpcService
public class BOMDomainService extends BOMServiceImplBase {

  private final Logger logger = LogManager.getLogger();

  private Random       rand   = new Random(1);

  @Override
  public void getBOMList(Empty request, StreamObserver<BOM> responseObserver) {
    for (int i = 1; i <= rand.nextInt(40); i++) {
      PartSpec part = PartSpec.newBuilder().setPartNumber("part-1").setCageCode("cage-1").build();
      BOM bom = BOM.newBuilder().setPartSpec(part).setDescription("some part").build();
      // Stream BOM response.
      responseObserver.onNext(bom);
    }

    // Complete server response.
    responseObserver.onCompleted();
  }
}

"Gateway"

Gateway service:

Interacts with the "domain" service via gRPC calls (blocking stub).

@Service
public class BOMGatewayService {

  private final Logger           logger = LogManager.getLogger();

  @GrpcClient("bom-service")
  private BOMServiceBlockingStub bomSvcStub;

  public List<BOM> getBOMList() {
    List<BOM> result = new ArrayList<>();

    try {
      Iterator<BOM> iter = bomSvcStub.getBOMList(Empty.getDefaultInstance());

      while (iter.hasNext()) {
        result.add(iter.next());
      }
    } catch (StatusRuntimeException e) {
      logger.warn("RPC failed: {}", e.getStatus());
    }

    return result;
  }
}

Gateway controller:

@RestController
@RequestMapping("/alisn/bom")
public class BOMController {

  @Autowired
  private BOMGatewayService service;

  @GetMapping(value = "/getBOMList", produces = { MediaType.APPLICATION_JSON_VALUE })
  public DeferredResult<ResponseEntity<List<BOM>>> getBOMList() {
    DeferredResult<ResponseEntity<List<BOM>>> result = new DeferredResult<>();
    List<BOM> response = service.getBOMList();
    result.setResult(ResponseEntity.ok(response));
    return result;
  }
}

External "Client" service:

Interacts with the "gateway" service via REST calls. Does not use gRPC, but does use the message classes generated from the .proto file.

NOTE: I am not trying to get the list of "BOM"s here. If I try to use ResponseEntity<List<BOM>>, the getForEntity() method throws compiler errors. I'm not sure what I should be doing here and maybe that's part of the problem.

@Service
public class ClientService {

  private final Logger logger = LogManager.getLogger();

  @Autowired
  private RestTemplate restTemplate;

  @Scheduled(fixedDelay = 5000)
  public void getBOMList() {
    ResponseEntity<BOM> response = restTemplate
        .getForEntity("http://localhost:7090/alisn/bom/getBOMList", BOM.class);
    logger.info("Received:\n{}", response.getBody());
  }
}

I have attempted to exercise this in two ways:

  1. From a client Java Spring Boot service that uses a RestTemplate to make the REST call (the "Client" shown above).
  2. Making the HTTP GET request from Postman.

The response from both methods seems to be more or less the same.

Java client method:

Client console:

[2019-09-27 10:01:16.373] scheduling-1 ERROR: support.TaskUtils$LoggingErrorHandler:96 - Unexpected error occurred in scheduled task.
org.springframework.web.client.HttpServerErrorException$InternalServerError: 500 null
    at org.springframework.web.client.HttpServerErrorException.create(HttpServerErrorException.java:79) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:124) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:102) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.client.ResponseErrorHandler.handleError(ResponseErrorHandler.java:63) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.client.RestTemplate.handleResponse(RestTemplate.java:778) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:736) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:670) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.client.RestTemplate.getForEntity(RestTemplate.java:338) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at edu.mit.ll.alisn.exp.client.service.ClientService.getBOMList(ClientService.java:26) ~[classes/:?]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_201]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_201]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_201]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_201]
    at org.springframework.scheduling.support.ScheduledMethodRunnable.run(ScheduledMethodRunnable.java:84) ~[spring-context-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54) [spring-context-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_201]
    at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308) [?:1.8.0_201]
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180) [?:1.8.0_201]
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294) [?:1.8.0_201]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_201]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_201]
    at java.lang.Thread.run(Thread.java:748) [?:1.8.0_201]

"Gateway" console:

[2019-09-27 10:01:16.356] http-nio-7090-exec-3 ERROR: [/].[dispatcherServlet]:175 - Servlet.service() for servlet [dispatcherServlet] threw exception
com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Direct self-reference leading to cycle (through reference chain: java.util.ArrayList[0]->edu.mit.ll.alisn.exp.proto.BOM["unknownFields"]->com.google.protobuf.UnknownFieldSet["defaultInstanceForType"])
    at com.fasterxml.jackson.databind.exc.InvalidDefinitionException.from(InvalidDefinitionException.java:77) ~[jackson-databind-2.9.9.jar:2.9.9]
    at com.fasterxml.jackson.databind.SerializerProvider.reportBadDefinition(SerializerProvider.java:1191) ~[jackson-databind-2.9.9.jar:2.9.9]
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter._handleSelfReference(BeanPropertyWriter.java:944) ~[jackson-databind-2.9.9.jar:2.9.9]
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:721) ~[jackson-databind-2.9.9.jar:2.9.9]
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:719) ~[jackson-databind-2.9.9.jar:2.9.9]
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155) ~[jackson-databind-2.9.9.jar:2.9.9]
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:727) ~[jackson-databind-2.9.9.jar:2.9.9]
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:719) ~[jackson-databind-2.9.9.jar:2.9.9]
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155) ~[jackson-databind-2.9.9.jar:2.9.9]
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContentsUsing(CollectionSerializer.java:171) ~[jackson-databind-2.9.9.jar:2.9.9]
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:116) ~[jackson-databind-2.9.9.jar:2.9.9]
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:107) ~[jackson-databind-2.9.9.jar:2.9.9]
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:25) ~[jackson-databind-2.9.9.jar:2.9.9]
    at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider._serialize(DefaultSerializerProvider.java:480) ~[jackson-databind-2.9.9.jar:2.9.9]
    at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:400) ~[jackson-databind-2.9.9.jar:2.9.9]
    at com.fasterxml.jackson.databind.ObjectWriter$Prefetch.serialize(ObjectWriter.java:1392) ~[jackson-databind-2.9.9.jar:2.9.9]
    at com.fasterxml.jackson.databind.ObjectWriter.writeValue(ObjectWriter.java:913) ~[jackson-databind-2.9.9.jar:2.9.9]
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.writeInternal(AbstractJackson2HttpMessageConverter.java:287) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.http.converter.AbstractGenericHttpMessageConverter.write(AbstractGenericHttpMessageConverter.java:103) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:290) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.HttpEntityMethodProcessor.handleReturnValue(HttpEntityMethodProcessor.java:225) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:82) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:122) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:892) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:797) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1039) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:897) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.filterAndRecordMetrics(WebMvcMetricsFilter.java:114) ~[spring-boot-actuator-2.1.6.RELEASE.jar:2.1.6.RELEASE]
    at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:104) ~[spring-boot-actuator-2.1.6.RELEASE.jar:2.1.6.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:109) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:712) [tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.ApplicationDispatcher.doDispatch(ApplicationDispatcher.java:633) [tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.ApplicationDispatcher.dispatch(ApplicationDispatcher.java:601) [tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.AsyncContextImpl$AsyncRunnable.run(AsyncContextImpl.java:566) [tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.AsyncContextImpl.doInternalDispatch(AsyncContextImpl.java:355) [tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199) [tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490) [tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.connector.CoyoteAdapter.asyncDispatch(CoyoteAdapter.java:235) [tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.coyote.AbstractProcessor.dispatch(AbstractProcessor.java:241) [tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:53) [tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:853) [tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1587) [tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.21.jar:9.0.21]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_201]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_201]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.21.jar:9.0.21]
    at java.lang.Thread.run(Thread.java:748) [?:1.8.0_201]

Postman:

{
    "timestamp": "2019-09-27T14:03:38.530+0000",
    "status": 500,
    "error": "Internal Server Error",
    "message": "Type definition error: [simple type, class com.google.protobuf.UnknownFieldSet]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Direct self-reference leading to cycle (through reference chain: java.util.ArrayList[0]->edu.mit.ll.alisn.exp.proto.BOM[\"unknownFields\"]->com.google.protobuf.UnknownFieldSet[\"defaultInstanceForType\"])",
    "path": "/alisn/bom/getBOMList"
}

Any suggestions about what I'm doing wrong, or suggestions on a better way to do this type of process would be greatly appreciated.

UPDATE:

I am also including the bean configurations for the client and gateway service.

Client:

@Configuration
@EnableScheduling
@ComponentScan(XXXXXX)
public class Configurer {
  @Bean
  ProtobufHttpMessageConverter protobufHttpMessageConverter() {
    return new ProtobufJsonFormatHttpMessageConverter();
  }

  @Bean
  RestTemplate restTemplate(ProtobufHttpMessageConverter hmc) {
    return new RestTemplate(Arrays.asList(hmc));
  }
}

Gateway:

@Configuration
@ComponentScan(XXXXXX)
public class Configurer {
  @Bean
  ProtobufHttpMessageConverter protobufHttpMessageConverter() {
    return new ProtobufJsonFormatHttpMessageConverter();
  }
}

UPDATE:

I have done a simpler experiment where I created a new service that just returns one BOM object. This works just fine.

I don't understand why this works and the List<BOM> case does not. The information in the exception thrown seems to point to internal structure within the generated BOM class.

Gateway console:

[2019-10-02 08:37:25.960] http-nio-7090-exec-3 ERROR: [/].[dispatcherServlet]:175 - Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.http.converter.HttpMessageConversionException: Type definition error: [simple type, class com.google.protobuf.UnknownFieldSet$Parser]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class com.google.protobuf.UnknownFieldSet$Parser and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: java.util.ArrayList[0]->edu.mit.ll.alisn.exp.proto.BOM["unknownFields"]->com.google.protobuf.UnknownFieldSet["parserForType"])] with root cause
com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class com.google.protobuf.UnknownFieldSet$Parser and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: java.util.ArrayList[0]->edu.mit.ll.alisn.exp.proto.BOM["unknownFields"]->com.google.protobuf.UnknownFieldSet["parserForType"])

The reference to: java.util.ArrayList[0]->edu.mit.ll.alisn.exp.proto.BOM["unknownFields"]->com.google.protobuf.UnknownFieldSet["parserForType"] to me seems to indicate a problem with the internal structure of the BOM class, and yet I can return a single BOM without any problem.


回答1:


According to the Gateway log, it looks like jackson is having trouble converting proto to json.

can you try com.googlecode.protobuf.format.JsonFormat? I am not spring user, but there should be API for custom serialization. or, you can add custom serialization to jackson using JsonFormat but it sounds little weird.



来源：https://stackoverflow.com/questions/58136430/problem-returning-stream-of-responses-from-grpc-service-to-restful-client

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