March 27, 2023

Probably the most essential technical choices throughout designing API is to decide on the correct protocol for interchanging information. It’s not a simple job. You need to reply not less than just a few necessary questions – which can combine with API, if in case you have any community limitations, what’s the quantity and frequency of calls, and can the extent of your group’s technological maturity will let you keep this sooner or later?

Once you collect all the data, you possibly can evaluate completely different applied sciences to decide on one that matches you finest. You may choose and select between well-known SOAP, REST, or GraphQL. However on this article, we wish to introduce fairly a brand new participant within the microservices world – gRPC Distant Process Name.

What’s gRPC (Distant Process Name)?

gRPC is a cross-platform open-source Distant Process Name (RPC) framework initially created by Google. The platform makes use of Protocol Buffers as a knowledge serialization protocol, because the binary format requires fewer assets and messages are smaller. Additionally, a contract between the consumer and server is outlined in proto format, so code could be robotically generated. The framework depends on HTTP/2 (helps TLS) and past efficiency, interoperability, and code technology provides streaming options and channels.

Declaring strategies in contract

Have you ever learn our article about serializing information with Protocol Buffers? We’re going to add some extra definitions there:

message SearchRequest 
  string vin = 1;
  google.protobuf.Timestamp from = 2;
  google.protobuf.Timestamp to = 3;

message SearchResponse 
  repeated Geolocation geolocations = 1;

service GeolocationServer 
  rpc Insert(Geolocation) returns (google.protobuf.Empty);
  rpc Search(SearchRequest) returns (SearchResponse);

The construction of the file is fairly simple – however there are some things price noticing:

  • service GeolocationServer – service is asserted by key phrase with that identify
  • rpc Insert(Geolocation) – strategies are outlined by rpc key phrase, its identify, and request parameter sort
  • returns (google.protobuf.Empty) – and on the finish lastly a return sort. As you possibly can see you must at all times return any worth, on this case, is a wrapper for an empty construction
  • message SearchResponse repeated Geolocation geolocations = 1; – if you wish to return an inventory of objects, you must mark them as repeated and supply a reputation for the sector

Construct configuration

We will mix options of Spring Boot and simplify the setup of gRPC server by utilizing the devoted library GitHub – yidongnan/grpc-spring-boot-starter: Spring Boot starter module for gRPC framework. (comply with the set up information there).

It allow us to use all of the goodness of the Spring framework (reminiscent of Dependency Injection or Annotations).

Now you’re able to generate Java code! ./gradlew generateProto

Server implementation

To implement the server for our strategies definition, to begin with, we now have to increase the correct summary class, which had been generated within the earlier step:

public class GeolocationServer extends GeolocationServerGrpc.GeolocationServerImplBase

As the subsequent step add the @GrpcService annotation on the class stage to register gRPC server and override server strategies:

public void insert(Geolocation request, StreamObserver<Empty> responseObserver) 
    GeolocationEvent geolocationEvent = convertToGeolocationEvent(request);;


public void search(SearchRequest request, StreamObserver<SearchResponse> responseObserver) 
    Record<GeolocationEvent> geolocationEvents = geolocationRepository.searchByVinAndOccurredOnFromTo(

    Record<Geolocation> geolocations =;


  • StreamObserver<> responseObserver – stream of messages to ship
  • responseObserver.onNext() – writes responses to the consumer. Unary calls should invoke onNext at most as soon as
  • responseObserver.onCompleted() – receives a notification of profitable stream completion

We now have to transform inside gRPC objects to our area entities:

personal GeolocationEvent convertToGeolocationEvent(Geolocation request) 
    On the spot occurredOn = convertTimestampToInstant(request.getOccurredOn());
    return new GeolocationEvent(
        new Coordinates(request.getCoordinates().getLatitude(), request.getCoordinates().getLongitude())

personal On the spot convertTimestampToInstant(Timestamp timestamp) 
    return On the spot.ofEpochSecond(timestamp.getSeconds(), timestamp.getNanos());

Error dealing with

Neither consumer at all times sends us a sound message nor our system is resilient sufficient to deal with all errors, so we now have to supply methods to deal with exceptions.

If an error happens, gRPC returns one in all its error standing codes as a substitute, with an optionally available description.

We will deal with it with ease in a Spring’s manner, utilizing annotations already accessible within the library:

public class GrpcExceptionAdvice 

    public Standing handleInvalidArgument(IllegalArgumentException e) 
        return Standing.INVALID_ARGUMENT.withDescription(e.getMessage()).withCause(e);

  • @GrpcAdvice – marks the category as a container for particular exception handlers
  • @GrpcExceptionHandler – technique to be invoked when an exception specified as an argument is thrown

Now we ensured that our error messages are clear and significant for purchasers.

gRPC – is that the proper choice for you?

As demonstrated on this article, gRPC integrates effectively with Spring Boot, so when you’re aware of it, the educational curve is clean.

gRPC is a worthy choice to think about once you’re working with low latency, extremely scalable, distributed programs. It supplies an correct, environment friendly, and language-independent protocol.

Try the official documentation for extra information! gRPC