This is a simple calculator to demonstrate the use of the following tools:

• Golang
• Protocol Buffers
• gRPC
• Go modules

The calculator server implements a method Calculate add, substract, multiply or divide two numbers.

To get information about system requirements, please visit the Golang MinimumRequirements Wiki Page

To install Golang, please follow the instructions on the Golang Getting Started Page

As the server implements a generated Protocol Buffer file, this file needs to be generated first.
Therfor please download the protocol buffer compiler protoc with the gRPC go plugin:

$ go get -u github.com/golang/protobuf/protoc-gen-go

After you installed the compiler you can generate the go-code file from the Protocol Buffer:

$ protoc -I calculator/ calculator/calculator.proto --go_out=plugins=grpc:calculator

As this project supports Go modules, it is not necessary anymore to "go get" all dependencies.
You can run the program either by running the two .go files for server and client:

1. $ go run server/calculator_server.go (first time Go modules are allocated)
2. $ go run client/calculator_client.go <number><operator><number>

Or you build executable files by running:

1. $ go build server/calculator_server.go
2. $ go build client/calculator_client.go

Afterwards you can run the client like:
./calculator_client <number><operator><number> on Unix
or
calculator_client.exe <number><operator><number> on Windows

For more information about gRPC please visit:

gRPC.io

For more information about Protocol Buffers please visit:

Protocol Buffers - Google Developers Guide