CODEWITHSUNDEEP
protocol-buffersgrpc-javaproto
Rajat Goyal
Rajat Goyal

Reputation: 475

customization in protobuf java generated code

We have a use case where, we have many RPC defined in different-different .proto files , and we generate a java based grpc stub code by using google's protobuf-java & protoc-gen-grpc-java as gradle plugin. The requirement is we want to generate a new Service which flips the request, response and add stream to new flipped rpc. So for example :

service Greeter {
  // Sends a greeting
  rpc SayHello (HelloRequest) returns (HelloReply) {}
}

// The request message containing the user's name.
message HelloRequest {
  string name = 1;
}

// The response message containing the greetings
message HelloReply {
  string message = 1;
}

to be converted to like

service Greeter {
  // Sends a greeting
  rpc SayHello (HelloRequest) returns (HelloReply) {}
  rpc SayHelloStreaming (stream HelloReply) returns (stream HelloRequest) {}
}

// The request message containing the user's name.
message HelloRequest {
  string name = 1;
}

// The response message containing the greetings
message HelloReply {
  string message = 1;
}

In java generated code I should be having 2 services for each original service. We just want the final java generated code to be having 2 services, the parser may/may not update original .proto files.

Is this customization possible with current protoc ? Can we extend the plugin and write ours -> Can someone please give some pointers.

Upvotes: 0

Views: 697

Answers (1)

DazWilkin
DazWilkin

Reputation: 40326

Your question is unclear to me.

Revising proto files is a fundamental requirement of gRPC.

The Java tutorial on https://grpc.io includes an example of adding a method to a service. In part, this is because adding|removing|updating methods|messages|fields is a common behavior.

NOTE To clarify nomenclature, in your example, you're proposing adding a method to an existing service (definition). If you consider the proto as defining an API, this represents a non-breaking change. See Versioning gRPC services for a good overview. Existing clients will continue to work (they are only aware of SayHello) while new clients will be aware of SayHelloStreaming too.

Upvotes: 0

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