An example of how three services, can communicate between each other using Rest gRPC and Kafka.
The sources of the program:
The runner class here
The flow of the program
Client ---> [REST request] ---> [KAKA PUBLISHER] ---> [KAFKA CONSUMER] ---> [gRPC CLIENT]
---> [gRPC SERVER] ---> [KAKA PUBLISHER] ---> [KAFKA CONSUMER] ---> [REST response] ---> Client
If the client make an Http request into:
http://localhost:4000//communication/restKafkaGRPC/
The logs of the transaction show:
REST request: hello world from rest
KAFKA Publisher: hello world from rest and Kafka publisher
KAFKA Consumer: hello world from rest and Kafka publisher and Kafka consumer
gRPC Client:hello world from rest and Kafka publisher and Kafka consumer and gRPC client
gRPC Server:hello world from rest and Kafka publisher and Kafka consumer and gRPC client and gRPC server
KAFKA Publisher: hello world from rest and Kafka publisher and Kafka consumer and gRPC client and gRPC server and Kafka publisher
KAFKA Consumer: hello world from rest and Kafka publisher and Kafka consumer and gRPC client and gRPC server and Kafka publisher and Kafka consumer
REST response: hello world from rest and Kafka publisher and Kafka consumer and gRPC client and gRPC server and Kafka publisher and Kafka consumer
############################################################################################
End of transaction with Message:
HELLO WORLD FROM REST AND KAFKA PUBLISHER AND KAFKA CONSUMER AND GRPC CLIENT AND GRPC SERVER AND KAFKA PUBLISHER AND KAFKA CONSUMER
############################################################################################
The response to the client show:
"HELLO WORLD FROM REST AND KAFKA PUBLISHER AND KAFKA CONSUMER AND GRPC CLIENT AND GRPC SERVER AND KAFKA PUBLISHER AND KAFKA CONSUMER"