gRPC 101

if you haven't installed google's protocol buffers, see the prerequisites part at the bottom.

Setup of repository

1. make go.mod file with:

   $ go mod init [link to repo without "https://"]

   your repo should be on the public github. i couldn't get it to work on the itu instance.

   Tip!

   You can use example.com, if you don't have a repo.

2. make a .proto file in a sub-directory, for example time/time.proto and fill it with IDL.

   • notice line 3 and 4.

     package time;
     option go_package = "https://github.itu.dk/nako/DISYS-week5;time";

     the go_package should equal a link to your repo, a semicolon and then the package name.

     Tip!

     Notice the semicolon and the package-name at the end of the link. If you used example.com, you should write ... = "https://example.com/;packagename";.

3. run command:

   $ protoc --go_out=. --go_opt=paths=source_relative --go-grpc_out=. --go-grpc_opt=paths=source_relative time/time.proto

   which should create the two pb.go files. Remember to change "time" to your directory and file name.

4. run command:

   $ go mod tidy

   to install dependencies and create the go.sum file.

5. create a client\client.go file with the client_template.txt as template.

   Tip!

   When implementing your grpc methods, you should write the link without "https://" and with the packagename at the end. If you used example.com, you should write "example.com/package". If you used a long name for your package, you can write a shorter name before the quotation marks, for example pckg "example.com/longpackagename".

6. create a server\server.go file with the server_template.txt as template.

7. switch out the "myPackage" with your actual package.

8. switch our the method names with actual method names.

9. add more methods to the client.go file, so that there's a method for each request in the .proto file.

10. when everything is compilable, open a terminal, change directory to the server folder, and run the command:

    $ go run .

    this will start your server.

11. open a new terminal, change directory to the client folder and run the command:

    $ go run .

    this will run the requests listed in the main method of the client file.

12. create a Dockerfile like the one in this repository.

13. change line 11, 12 and 16 to match your repository.

    from now on

    please remember to commit and push changes to the files in your repository before running the program.

    the following docker commands will clone your repository (maybe to the virtual machine?), so changes to files will not be applied, if you don't git commit yeet before.

    the only exception (i think) is changes to the client.go file, since it's run locally on your computer, but just connects to the server in docker.

14. run command:

    $ docker build -t test --no-cache .

    to build the code. what you write after -t will be the name of your image, so the name of the image here is test. the name doesn't matter, but it helps you identify it in the docker desktop app.

15. run command:

    $ docker run -p 9080:9080 -tid test

    to run the code in a docker container. if you changed the name of the image from test, make sure to change it in this command as well.

16. change directory into your client folder.

17. run command:

    $ go run .

    to run the code.

Prerequisites

1. before starting, install google's protocol buffers:

   • go to this link: https://developers.google.com/protocol-buffers/docs/downloads
   • click on the "release page" link.
   • find the version you need and download it.
   • as per october 2021, if your on windows, it's the third from the bottom, protoc-3.18.1-win64.zip.

2. unzip the downloaded file somewhere "safe".

   • on my windows machine, i placed it in C:\Program Files\Protoc

3. add the path to the bin folder to your system variables.

   • on windows, click the windows key and search for "system", then there should come something up like "edit the system environment variables".

   • click the button "environment variables..." at the bottom.

   • in the bottom list select the variable called "path" and click "edit ..."

   • in the pop-up window, click "new..."

   • paste the total path to the bin folder into the text field.

     my path is C:\Program Files\Protoc\bin.

   • click "ok".

4. open a terminal and run these commands:

   $ go install google.golang.org/protobuf/cmd/protoc-gen-go@v1.26

   $ go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@v1.1