protoc generated c++ files

[Paul Lemay]

Hello,

I have this proto files where the root file is defined as below:

syntax = "proto3";

package upfservice.v1;

import "session.proto";

import "hello.proto";

// The Upfu_BfRuntime service definition.

service UPFService {

// Initial handshake initiated by client.

rpc Hello(stream HelloRequest) returns (stream HelloResponse) {}

// Client shutdown (resource can be cleaned up)

rpc Bye(ByeRequest) returns (ByeResponse) {}

// Ping request

rpc Ping(PingRequest) returns (PingResponse) {}

// Session management bi-directional streaming api.

rpc Session(stream ServiceDataSessionRequest) returns (stream ServiceDataSessionResponse) {}

// UR collection server streaming (client call this one then wait for continuous UR stream)

rpc UsageReport(UsageReportRequest) returns (stream UsageReports) {}

}

The generated file gives me a typedef to work with:

typedef WithAsyncMethod_Hello<WithAsyncMethod_Bye<WithAsyncMethod_Ping<WithAsyncMethod_Session<WithAsyncMethod_UsageReport<Service > > > > > AsyncService;

It does not seems right since I can't use the AsyncService to do anything. Is it because there is a limit of 1 asynchronous stream rpc per service?

[Derek Perez]

Are you generating the C++ code with the proper grpc plugin as well? Services won't generate useful stubs without that.

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[Derek Perez]

Here's a link to the docs for the protoc grpc plugin: 

https://grpc.io/docs/tutorials/basic/cpp/#generating-client-and-server-code  

[Paul Lemay]

Hello Derek,

thanks for your help. 

Yes, the procedure to compile is right. If I keep only 1 async rpc stream (i.e., say rpc Session), and I recompile, I get the typedef that I am expecting:

typedef WithAsyncMethod_Session<Service > AsyncService;

Even if there is multiple async rpc stream there is only 1 typedef produced where I would expect many. This lead me to believe that the service must be arrange to handle a single async rpc stream or that our proto files are are defined properly. Here is the main that includes the other:

syntax = "proto3";

package upfservice.v1;

import "session.proto";

import "hello.proto";

// The Upfu_BfRuntime service definition.

service UPFService {

// Initial handshake initiated by client.

rpc Hello(stream HelloRequest) returns (stream HelloResponse) {}

// Client shutdown (resource can be cleaned up)

rpc Bye(ByeRequest) returns (ByeResponse) {}

// Ping request

rpc Ping(PingRequest) returns (PingResponse) {}

// Session management bi-directional streaming api.

rpc Session(stream ServiceDataSessionRequest) returns (stream ServiceDataSessionResponse) {}

// UR collection server streaming (client call this one then wait for continuous UR stream)

rpc UsageReport(UsageReportRequest) returns (stream UsageReports) {}

}

What typedef sould I expect out of there?

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[Paul Lemay]

Finally,

The typedef template above was generated properly and I was mislead by the template error message that was raised at compiled time. When invoking the Request session, the stream parameter passed was wrong.

mCallData->GetService()->RequestSession(&mCtx, &mStream,
mCallData->GetCompletionQueue(),
mCallData->GetCompletionQueue(), &mProceedFunction);

I mismatched request and response in the ServerAsyncReaderWriter declaration:

grpc::ServerAsyncReaderWriter<Response, Request> mStream

So to the question I was asking, yes, it is possible to have multiple rpc streams in a single grpc service.