gRPC Go Example

This is a short project showing the four different classes of gRPC calls (in terms of data-streaming) that can be made from both client and server side using Golang with minimal noise involved, meaning this is a minimalistic implementation of the calls simply to show how each of them work.

This project was created using a Windows environment. When executing any commands in other environments, you may need to make the necessary changes to accomodate for things like the exe extension used.

All commands are from the perspective of the project root.

Concepts

RPC Types

• Unary - Neither the client nor the server will be streaming any more than one message to each other.
• Server Stream - The server will stream responses to the client, the client will only send one request.
• Client Stream - The client will stream requests to the server, the server will only send one response.
• Bidirectional Stream - Both the client and the server will be streaming messages to each other.

Resources

• There is only one resource that is sent through messages, it is called FooBarBaz. As the name suggests, this is a completely arbitrary data structure. It is composed of three fields, Foo of type string, Bar of type int64, and baz of type bool. Each of these are included to show how different data types can be sent encapsulated in a struct.

Requests

• Requests from the client are composed of only one field, FooBarBaz of type FooBarBaz. The data sent is purely to show that data can be sent.

Responses

• Responses from the server are composed of only one field, Success of type bool. This field is used to indicate that all went well on the server.

Processing Time

• In an effort to show what is actually going on during the streaming events, I added in a function to the ./src/util.go file called SimulateProcessing. The purpose of this function is solely to put the current thread to sleep for a random amount of time while the streaming is occurring. This allows one to observe the requests and responses as they are happening in real time, and also lends itself to a more realistic model of gRPC in which requests and responses would indeed be slowed down by some sort of processing time.

Project Structure

• bin
  • Compiled project files will go here.
• pkg
  • Empty
• src
  • client
    • All code specific to the gRPC client is here.
  • pb
    • foo-bar-baz.proto This is the protocol buffer file.
    • foo-bar-baz.pb.go This is the Go code generated from protoc on the preceding file.
  • server
    • All code specific to the gRPC server is here.
  • util.go contains some code useful to both the client and server.

The Server

Building

• go.exe build -o "./bin/server.exe" "./src/server"

Running

• ./bin/server.exe

The server listens on port 9000 for incoming requests. The client is aware of this by default, no additional configuration is needed.

The Client

Building

• go.exe build -o "./bin/client.exe" "./src/client"

Running

• ./bin/client.exe <request-type>

  Where <request-type> is one of unary, server-stream, client-stream, or bidirectional-stream.

The request type you provide is what type of request the client will issue to the server. This is how you can test each type of request available.

Protocol Buffer Compilation

The protocol buffer file in this project (./src/pb/foo-bar-baz.proto) has already been compiled into it's Go counterpart, but if you are making changes and would like to see them reflected in the project, continue reading.

1. Install protoc and ensure it is in your Path.

2. Install the grpc plugin for protoc:

   go.exe get -u github.com/golang/protobug/protoc-gen-go

3. Perform the protoc compilation

   protoc.exe "./src/pb/foo-bar-baz.proto" --go_out=plugins=grpc:"./src"

This tells protoc to compile the proto file located at ./src/pb/foo-bar-baz.proto into Go using the grpc plugin, and placing the output at ./src (and then into its given package directory, defined in the proto file).

Everything should be updated now in the generated code, all previous compilations are overwritten (unless you changed any names or directories).

Notes

• I am not an authority on anything RPC or gRPC related. I made this for fun and as a way to flesh out these calls for myself. I am putting it online in order to keep it safe from hardware failures, and in case anyone else may be looking for a pure implementation of the gRPC calls without any unnecessary example business logic.
• A majority of these concepts I learned through Michael Van Sickle's PluralSight course Enhancing Application Communication with gRPC and I highly recommend it if you want to see a more real world example of these RPCs in action.