gosdk

README

0chain/gosdk

The 0chain client SDK is written in Go programming language. This repository currently supports the following platforms:

• OSX Mojave 10.14.5
• LINUX (Ubuntu/bionic).
  • This includes all Ubuntu 18+ platforms, so Ubuntu 19, Linux Mint 19 etc. (apt based package installer)
• LINUX (RHEL/CENTOS 7+)
  • All Releases based on RHEL 7+, Centos 7+, Fedora 30 etc. (yum based package installer)

It is possible to support the sdk for other variations of Linux as well.

Usage

• Save below code as sdkversion.go

    package main
  
    import (
        "fmt"
  
        "github.com/0chain/gosdk/zcncore"
    )
  
    func main() {
        fmt.Println("gosdk version: ", zcncore.GetVersion())
    }
  

• Run below command: (if you don't have gosdk already in your GOPATH)

    go get github.com/0chain/gosdk
  

• Build the sample application sdkversion

    go build -o sdkversion sdkversion.go
  

• Run the executable

    ./sdkversion
  

• If it prints the gosdk version installed then setup is complete.

Mobile Builds (iOS and Android)

• gosdk can be build to use on Mobile platforms iOS and Android using gomobile.

• Xcode Command Line Tools is required to build SDK for iOS.

• Android studio with NDK is required to build SDK for Android

• Run below command for the first time to setup gomobile environment

    make setup-gomobile
  

• Incase Go package not found in golang.org/x/mobile/bind, run the command go get golang.org/x/mobile/bind

• Use below commands in the root folder of the repo to build Mobile SDK

    For iOS only:
            make build-ios
    For Android only:
            make build-android
  

How to expose a gosdk function to mobilesdk

Examples:

• mobilesdk/sdk/common.go which exports the functions in core/encryption/hash.go.

Steps:

1. If you are exposing:

   • a new function from an existing file like zboxcore/sdk/allocation.go, you should add a function to mobilesdksdk/zbox/allocation.go which should call the gosdk function you intend to expose.
   • a function from a new file, you should create a new <filename>.go file for it, in the same style as mobilesdksdk/zbox/allocation.go & in the file created, you should call the gosdk function you intend to expose.

2. Build the Mobile SDK as mentioned in the 'Mobile Builds' section of this file to build the aar file used in the mobile application you are developing.

How to export a gosdk function to WebAssembly

Examples:

• wasmsdk/ethwallet.go which exports the functions in zcncore/ethwallet.go.
• wasmsdk/wallet.go which exports one function in zcncore/wallet.go.

Steps:

1. If you are exporting:

   • a new function from zcncore/wallet.go, you should add to wasmsdk/wallet.go

   • a function from a new file, you should create a new <filename>.go file for it, in the same style as wasmsdk/wallet.go or wasmsdk/ethwallet.go

2. In func main(), https://github.com/0chain/gosdk/wasmsdk/proxy.go, you need to add this line:

       js.Global().Set("YOURFUNC", js.FuncOf(YOURFUNC))
   

3. Now you need to compile a new <any_name>.wasm (e.g. proxy.wasm). Currently, the right version to compile wasm is with Go version 1.16. So make sure you have it to make the wasm build works properly. In order to compile, run the following command:

   $ GOOS=js CGO_ENABLED=0 GOARCH=wasm go build -o <any_name>.wasm github.com/0chain/gosdk/wasmsdk
   

An important note regarding export of a async function

If your golang function requires to be run asynchronously, you need to add more wrapper code where you are returning a Promise object.

See "InitZCNSDK" example:

func InitZCNSDK(this js.Value, p []js.Value) interface{} {
	blockWorker := p[0].String()
	signscheme := p[1].String()

	handler := js.FuncOf(func(this js.Value, args []js.Value) interface{} {
		resolve := args[0]
		// reject := args[1]

		go func() {
			err := zcncore.InitZCNSDK(blockWorker, signscheme)
			if err != nil {
				fmt.Println("error:", err)
			}
			resolve.Invoke()
		}()

		return nil
	})

	// Create and return the Promise object
	promiseConstructor := js.Global().Get("Promise")
	return promiseConstructor.New(handler)
}

How to run unit test

BLS unit test

It's advisable to put GOPATH as $TOP/../go, to avoid conflicts with this command: go build ./...

To run all the unit tests in gosdk: go test github.com/0chain/gosdk/zboxcore/sdk -v`

$ go test ./...

To run all the unit tests in bls0chain_test.go, run this command from $TOP: go test github.com/0chain/gosdk/core/zcncrypto -v

To run a specific unit test in bls0chain_test.go such as TestSignatureScheme, run this: go test github.com/0chain/gosdk/core/zcncrypto -v -run TestSignatureScheme

To run the coverage test in `gosdk:

$ go test <path_to_folder> -coverprofile=coverage.out
$ go tool cover -html=coverage.out

WebAssembly

Using go test

1. You need to install nodejs first, see this page for further instructions

2. Add /path/to/go/misc/wasm to your $PATH environment variable (so that "go test" can find "go_js_wasm_exec"). For example in ubuntu, run $export PATH=$PATH:/usr/local/go/misc/wasm/.

3. You can then run the test by following the BLS unit test above with adding the prefix environment GOOS=js CGO_ENABLED=0 GOARCH=wasm:

   go test -tags test -v github.com/0chain/gosdk/wasmsdk
   

Test in the client

1. After you successfully export the wasm package to proxy.wasm, now you can test that proxy.wasm.

2. We currently have a test page going at the js-client-sdk repo: https://github.com/0chain/js-client-sdk/blob/gosdk/test/index.html

3. You can replace the proxy.wasm at https://github.com/0chain/js-client-sdk/blob/gosdk/test/proxy.wasm

4. You need to startup a special test server in order to stream WASM files. Use this command from js-client-sdk $TOP: sudo php -S localhost:82 test/server.php

5. See "testethwallet" function in index.html for how the testing for ethwallet.go is done

6. To test the function you exported, it's probably as simple as calling "HelloWorld()". It should be a 1-liner.

How to install ffmepg

On linux ubuntu

sudo apt-get install ffmpeg
sudo apt-get install v4l-utils

FAQ

• How to install GO on any platform
• How to install different version of GO
• How to use go mod
• What is gomobile
• About XCode
• Android Studio
• Android NDK