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Native Node Modules, also known as Native addons, are the perfect tool for Node.js applications that need to run performance critical code, access system level APIs, or include existing C/C++ libraries. We have created the following video which will demonstrate how you can build your own Native Node.js for z/OS Module:

https://mediacenter.ibm.com/media/1_oqwm99sf

In our video, we set up the following package.json for our addon:

{
  "name": "hello",
  "version": "1.0.0",
  "description": "Building your own native Node module from scratch",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "gypfile": true,
  "dependencies": {
    "bindings": "^1.5.0",
    "node-addon-api": "^3.0.0"
  }
}

This allows our addon to make use of N-API, the node-addon-api module, as well as the bindings module. 


We set up a binding.gyp file where we name our addon hello, and add hello.cc as a source file:

{
  "targets": [
    {
      "target_name": "hello",
      "sources": [ "hello.cc" ],
      "include_dirs": [
        "<!@(node -p \"require('node-addon-api').include\")"
      ],
      'defines': [ 'NAPI_DISABLE_CPP_EXCEPTIONS' ],
    }
  ]
}

N-API C++ exceptions are currently not support on z/OS, which is why we need to define NAPI_DISABLE_CPP_EXCEPTIONS so that only JavaScript exceptions get thrown.


In hello.cc, we create a function that simply returns the string Hello, World!:

#include <napi.h>


Napi::String HelloWorld(const Napi::CallbackInfo& info) {
  Napi::Env env = info.Env();
  return Napi::String::New(env, "Hello, World!");
}


Napi::Object Init(Napi::Env env, Napi::Object exports) {
  Napi::String name = Napi::String::New(env, "helloWorld");
  Napi::Function function = Napi::Function::New(env, HelloWorld);
  exports.Set(name, function);
  return exports;
}


NODE_API_MODULE(NODE_GYP_MODULE_NAME, Init)

Since we named our addon hello, we can import it in JavaScript using:

const hello = require('bindings')('hello');

And we can call our C++ function from JavaScript using:

console.log(hello.helloWorld()); // 'Hello, World!'

If we want to allow other Node.js application to also use our addon, we also need to setup our index.js to export the addon:

var binding = require('bindings')('hello');
module.exports = binding;

This makes it possible to execute the command npm install <path-to-addon>, and require() our addon just like any other node module.

Congratulations, you have now built your own Native Node Module! For further information on Native Node Modules, you can check out the official Node.js documentation on C++ addons and N-API, as well as the node-addon-api module's documentation.