Micronaut 3.7.1 Documentation

• User Guide
• API Reference
• Configuration Reference
• Micronaut Guides

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Feature http-client documentation

• Micronaut HTTP Client documentation

Feature microstream documentation

• Micronaut MicroStream documentation

• https://microstream.one/

gRPC

• Introduction

• Core concept

• tutorials

• basictutorial in bitbucket

• git clone ssh://git@git02.unbelievable-machine.net:7999/jav/simplegrpcbasictutorial.git

• for eventhandling- simplest rpc call is implemented.

  simple RPC (one of 4 service methods of RPC) A simple RPC where the client sends a request to the server using the stub and waits for a response to come back, just like a normal function call.

  A server-side streaming RPC (one of 4 service methods of RPC) the client sends a request to the server and gets a stream to read a sequence of messages back. The client reads from the returned stream until there are no more messages.

Multi-module-setup

This project contains of three submodules as a Maven multi-module-project

• jhub-grpc-stack

  • ./mvnw install
  • contains the gRPC protobuf definition for
    • message type definition
    • service definition for eventhandling
  • Maven definition for class generation out of protobuf-grpc definition
  • generated gRPC classes
    • ServiceBaseDefinitions ( ClickServiceGrpc.ClickServiceImplBase ) (gRPC-server)
      • with generated service implementation out of protobuf definition
      • ClickServiceGrpc.ClickServiceImplBase

          public void pagesById(orange.business.jhub.PageIdRequest request, io.grpc.stub.StreamObserver<orange.business.jhub.PageView> responseObserver)
      
          public void userClicksByIdOnPage(orange.business.jhub.UserOnPageRequest request,
          io.grpc.stub.StreamObserver<orange.business.jhub.PageView> responseObserver)  
      

      On the server side, the server implements the methods declared by the service and runs a gRPC server to handle client calls.

    • generated synchronous and asynchronous Stub implementation (gRPC-client)
      • ClickServiceGrpc.ClickServiceBlockingStub or ClickServiceGrpc.ClickServiceStub

      public orange.business.jhub.PageIdCountResponse pagesCountById(orange.business.jhub.PageIdRequest request)
      
      public java.util.Iterator<orange.business.jhub.PageView> pagesById(orange.business.jhub.PageIdRequest request)
      

      On the client side, the client has a local object known as stub that implements the same methods as the service. The methods wrap the parameters for the call in the appropriate protocol buffer message type, send the requests to the server, and return the server’s protocol buffer responses

• microstream-grpc-server

  mn create-app orange.business.jhub.microstream-grpc-server --features=microstream,serialization-jackson,micronaut-validation,grpc,kafka --build=maven --lang=java

  • Microservice stores ingested raw data from Kafka topic into Microstream
  • Micronaut application along with Microstream definìtion
  • Micronaut application along with gRPC server provisioning
  • asks the server sth:

  grpcurl -d '{"pageid":"Page_81", "userid":"User_2"}' -plaintext 127.0.0.1:5050 ClickService.UserClicksByIdOnPage

• microstream-grpc-client

  • Client asks grpc-server to gather rawdata over gRPC endpoint, stores some aggregates and provides data over gRPC API definition as well
  • Client is implemented as server as well for unlimited request possibility

  mn create-app orange.business.jhub.microstream-grpc-client --features=microstream,serialization-jackson,micronaut-validation,grpc --build=maven --lang=java

HowTo start the microstream-service

./mvnw install (this starts the docker-compose network for confluent platform and is installing datagen connector during test-compile)

./mvnw mn:run -pl microstream-grpc-server

./mvnw  exec:java -pl microstream-grpc-client

ask the client sth:

grpcurl  -d  '{"pageid":"Page_81"}' -plaintext 127.0.0.1:50051 ClickAggService.PagesCountById

grpcurl  127.0.0.1:50051 describe ClickAggService

to debug it as java app in your ide add the folllowing jvm-option:

java --add-exports=java.base/jdk.internal.misc=ALL-UNNAMED -jar microstream-grpc-client/target/microstream-grpc-client-0.1-SNAPSHOT.jar