Purpose

This is a small library which can be used to access remote gRPC services from java code even if neither the service specific client nor its proto file is available. For parameter input and message output, we use json, similar to grpcurl. This should work on all gRPC servers which expose the gRPC standard reflection API.

Also, this code can be used as a starting point for your own development to cover any other needs related to access gRPC services without the service-specific client. It is MIT-licensed, so feel free to go ahead and derive from it according to your needs.

How to Build

Prerequisite to building the library are Java 17 (or higher) and Maven 3.8 (or higher). From the directory in which this README file resides, simply issue

mvn package

at the command line. The full library, excluding dependencies and test classes, will be written to

target/grpc-json-java-<version>.jar

How to use

Have a look at the demo class DemoMain and at the classes' javadoc code to learn how to use the code. DemoMain contains a main method, so it can be called as such:

java -cp <classpath with all dependencies> com.github.malamut2.DemoMain localhost 6969 myService myMethod {\"myParameter\":123}

This will contact a gRPC server running on your local machine on port 6969, and execute myService.myMethod, using default input parameters except for myParameter, which will be set to 123.