Go and gRPC: Protocol Buffers, Services, Clients and Streaming

gRPC is an open-source remote procedure call framework used for communication between services. This article outlines a Go learning path from defining a service with Protocol Buffers to implementing a server, creating a client and sending a stream of responses. Installation details can change with Go, protoc and plugin versions.

What gRPC and Protocol Buffers do

With remote procedure calls, a client can call a method exposed by a server as though it were calling a function in an application. The source article describes gRPC as using HTTP/2 for transport and Protocol Buffers as an interface definition language (IDL) for data and service definitions. It names Go, Java, Python, C++, C# and Ruby among supported languages.

Set up a Go project

Prepare a Go environment, install the gRPC packages and install the Protocol Buffer compiler. Organize the project with separate server and client code. Follow current installation instructions for the versions of Go, gRPC and protoc in use.

Define a service in a proto file

Create a proto directory and a file such as calculator.proto. A proto file can declare a package, define request and response messages, and specify a service and the methods a client can call. A method is the operation exposed by that service; in this context, “switch” refers to defining a callable method.

After the definitions are ready, use protoc with the appropriate Go plugins to generate Go code, and install the gRPC packages required by the generated files. A VS Code Protocol Buffer extension can help edit proto files.

Implement the server and client

Implement the generated service interface in Go, create a server that registers the service and then write a client that connects and calls its methods. The source course also demonstrates using a tool it calls EVA (Error Value Analyzer) to test a gRPC service; check the tool’s current availability and instructions before relying on it.

Update schemas and handle data types

When a service changes, update the proto file and regenerate code. Field tags identify message fields, so schema changes should be planned carefully and follow Protocol Buffer compatibility rules. The source covers common types such as int32, int64, string and bool, as well as timestamp values.

Stream responses from a server

gRPC supports streaming APIs. In server streaming, one request can receive a sequence of responses from the server. The course uses a Fibonacci sequence as an example of producing a series of values. The precise service definition and generated code depend on the proto schema and toolchain versions.