Invoke NodeJs package static methods in GoLang app

This article provides an introduction to cross-technology invocation of static methods.

Javonet allows you to reference and use modules or packages written in (Java/Kotlin/Groovy/Clojure, C#/VB.NET, Ruby, Perl, Python, JavaScript/TypeScript) like they were created in your technology. If have not yet created your first project check Javonet overview and quick start guides for your technology.

With Javonet you can interact with static methods from NodeJs package like they were available in GoLang but invocation must be performed through Javonet SDK API, passing the name of the target method as String.

Javonet allows you to pass any GoLang value type as argument to static method from NodeJs package. In example: int, float, string, char, long and other. For reference type arguments (instances of other classes) you can create such instance with Javonet and pass the Invocation Context variable referencing that object as argument of static method invocation.

Use custom NodeJs package static methods in GoLang application

With Javonet it is possible to reference any custom NodeJs package and interact with public static methods declared on types defined within that module almost the same as with any other GoLang library.

Snippet below represents the sample code from NodeJs package which contains class and its methods:

const fs = require('fs').promises;

class TestClass {

    static multiplyByTwo(a) {
    	return 2 * a;
    }
    
    multiplyTwoNumbers(a, b) {
    	return a * b
    }
}

module.exports = TestClassstatic multiplyByTwo(a) {
	return 2 * a;
}

multiplyTwoNumbers(a, b) {
	return a * b
}

It is possible to invoke one of the declared static methods from NodeJs package using following GoLang code.

package main

import (
	"fmt"
	Javonet "javonet.com/javonet"
)

var resourcesDirectory string = "."

func main() {
	_ = resourcesDirectory

  	// use Activate only once in your app
  	Javonet.Activate("your-license-key")
  	
  	// create called runtime context
  	calledRuntime, _ := Javonet.InMemory().Nodejs()
  	
  	// set up variables
  	libraryPath := resourcesDirectory + "/TestClass.js"
  	className := "TestClass"
  	
  	// load custom library
  	calledRuntime.LoadLibrary(libraryPath)
  	
  	// get type from the runtime
  	calledRuntimeType, _ := calledRuntime.GetType(className).Execute()
  	
  	// invoke type's static method
  	response, _ := calledRuntimeType.InvokeStaticMethod("multiplyByTwo", 25).Execute()
  	
  	// get value from response
  	result := response.GetValue().(int32)
  	
  	// write result to console
  	fmt.Println(result)
}
const fs = require('fs').promises;

class TestClass {

    static multiplyByTwo(a) {
    	return 2 * a;
    }
    
    multiplyTwoNumbers(a, b) {
    	return a * b
    }
}

module.exports = TestClass// use Activate only once in your app
Javonet.Activate("your-license-key")

// create called runtime context
calledRuntime, _ := Javonet.InMemory().Nodejs()

// set up variables
libraryPath := resourcesDirectory + "/TestClass.js"
className := "TestClass"

// load custom library
calledRuntime.LoadLibrary(libraryPath)

// get type from the runtime
calledRuntimeType, _ := calledRuntime.GetType(className).Execute()

// invoke type's static method
response, _ := calledRuntimeType.InvokeStaticMethod("multiplyByTwo", 25).Execute()

// get value from response
result := response.GetValue().(int32)

// write result to console
fmt.Println(result)

In code snippet above you can see how easily you can activate Javonet and instruct it using inMemory() method to create new RuntimeContext that will run nodejs-package runtime within your current process. Next with addLibrary method it triggers the load of required nodejs-package module and allows you to interact with any classes and their static methods defined in that package.

Further calls to invokeStaticMethod() allows to call "multiplyByTwo" nodejs-package static method and pass the value type arguments. With Javonet you can invoke methods with any number and any type of arguments including value type arguments, reference type arguments, arrays and collections.

You can receive and further process and type of result returned by called nodejs-package method, regardless if it is reference type that will get returned as another instance of Invocation Context that you can use for further interaction, or value type that you can obtain as golang value with getValue() method.

Use framework static methods in GoLang application

With Javonet you can interact not only with any custom nodejs-package module but also with any nodejs-package framework objects. The same steps are required to use types and methods from standard NodeJs package framework class:

package main

import (
	"fmt"
	Javonet "javonet.com/javonet"
)

var resourcesDirectory string = "."

func main() {
	_ = resourcesDirectory

  	// use Activate only once in your app
  	Javonet.Activate("your-license-key")
  	
  	// create called runtime context
  	calledRuntime, _ := Javonet.InMemory().Nodejs()
  	
  	// get type from the runtime
  	calledRuntimeType, _ := calledRuntime.GetType("Math").Execute()
  	
  	// invoke type's static method
  	response, _ := calledRuntimeType.InvokeStaticMethod("abs", -50).Execute()
  	
  	// get value from response
  	result := response.GetValue().(int32)
  	
  	// write result to console
  	fmt.Println(result)
}
const fs = require('fs').promises;

class TestClass {

    // empty
}

module.exports = TestClass// use Activate only once in your app
Javonet.Activate("your-license-key")

// create called runtime context
calledRuntime, _ := Javonet.InMemory().Nodejs()

// get type from the runtime
calledRuntimeType, _ := calledRuntime.GetType("Math").Execute()

// invoke type's static method
response, _ := calledRuntimeType.InvokeStaticMethod("abs", -50).Execute()

// get value from response
result := response.GetValue().(int32)

// write result to console
fmt.Println(result)

In sample above you see how the Javonet allows to create an instance of NodeJs package Math class and interact with its static abs method. The same operation can be performed remotely by just changing the new Runtime Context invocation from in memory to tcp that will create and interact with your NodeJs package objects on any remote node, container or service that hosts Javonet Code Gateway. This way you can preserve the same logic in your application and instantly switch between monolithic and microservices architecture without the need to implement the integration layer based on web services or other remote invocation methods.

Read more about use cases and software architecture scenarios where Javonet runtime bridging technology can support your development process.