io.grpc | Java 9 compatible repackaging of gRPC libraries

To me, it looks like span and transaction names are missing (I only see HTTP GET instead of a name)

No, they are not missing. The reason you are seeing name as HTTP GET is due to preference for less cardinal names and the semantic conventions for tracing data. There is a detailed explanation about the naming conventions for the HTTP spans here https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/http.md#name. Any data generated by auto-instrumentation libraries will adhere to the semantic conventions specification. I am guessing the visualisation from the linked vendor is coming from manual instrumentation where you as an end user can give any name (although it is recommended everyone uses less cardinal values but there is not enforcement there). I don't think there is anything you can "fix" here.

Acording to this answer: https://stackoverflow.com/a/51236918/16651073 tomcat falls back to default logging if it can resolve the location

Can you try to save the properties without the spaces.

Like this: logging.file.name=application.logs

Add mavenCentral() in Build Script

I was able to create protoc.exe. Steps:

1. Checked out latest protobuf source.
2. Updated the source with farsounder matlab source and cmake file.
3. Followed https://github.com/protocolbuffers/protobuf/blob/master/cmake/README.md build the source.

Your approach is correct.

To authenticate code, you should use a Service Account.

Google provides a useful mechanism called Application Default Credentials (ADCs). See finding credentials automatically. When you use ADCs, Google's SDKs use a predefined mechanism to try to authenticate as the Service Account:

1. Checking GOOGLE_APPLICATION_CREDENTIALS in your environment. As you've tried;
2. When running on a GCP service (e.g. Compute Engine) by looking for the service's (Service Account) credentials. With Compute Engine, this is done by checking the so-called Metadata service.

For #1, you can either use GOOGLE_APPLICATION_CREDENTIALS in the process' environment or you can manually load the file as you appear to be trying in your code.

That all said:

1. I don't see where GoogleCredentials is being imported by your code?
2. Did you grant the Service Account a suitable role (permissions) so that it can access any other GCP services that it needs?

You should be able to use this List objects example.

The link above, finding credentials automatically, show show to create a Service Account, assign it a role and export it.

You will want to perhaps start (for development!) with roles/storage.objectAdmin (see IAM roles for Cloud Storage) and refine before deployment.

The protoc setup for as described in the current documentation is:

As far as I see, the problem is that in onNext() you're initiating new streamingCall to SecondProtoServiceGrpc each time MiddleService receives a new message from the FirstProtoServiceGrpc. Even though it's the same stream from the first server, the first message creates its own stream to second server, the second message creates its own stream to second server, etc. That explains why you get into the situation with "sending to much requests to second server".

Instead, the middle layer should mirror what first server does (for this example, we're looking only at the direction first -> middle -> second). When the first server creates a new stream (1) to the middle, the middle creates a new stream (2) to the second. When the middle server gets a message on the stream (1) (from the first server), it sends it to stream (2). When stream (1) is closed, stream (2) is closed too. And so on.

Same for the opposite direction, but vice-versa.

I guess your config is not correct. Instead of

Using mvn dependency:tree you can discover there's a mix of grpc-java 1.41.0 and 1.42.1 versions in your dependency tree. google-cloud-datastore:2.2.0 brings in grpc-api:1.42.1 but the other dependencies bring in grpc version 1.40.1.

grpc-java recommends always using requireUpperBoundDeps from maven-enforcer to catch Maven silently downgrading dependencies.