vrpc-nodejs-example v1.1.1

VRPC Example - Node.js

This project shows how you can easily bind some C++ code and use it from within Node.js.

How to run this example

Start with cloning or downloading this project from github.

1. Using docker

Using docker the installation is really simple and needs - besides docker - no dependencies on your system.

1. Build a docker image using the provided Dockerfile, e.g.:

   docker build . -t vrpc-nodejs-example

2. The run the example by typing:

   docker run vrpc-nodejs-example

2. On your operating system

For a local installation, make sure you have Node.js 8 and a C++14 capable compiler installed.

1. Install, using:

   npm install

2. Run

   npm start

How does this work?

The basic idea is that the C++ code in this project (cpp/Bar.hpp and cpp/Bar.cpp) is compiled together with the cpp/binding.cpp file (which expresses what to bind) and some sources from vrpc into a regular native addon.

Technically, this addon works like a factory, able to instantiate all registered classes and call corresponding functions on them. To use it in Node.js, you need to construct an instance of Vrpc, giving it the addon as argument:

const Vrpc = require('vrpc')
const addon = require('./build/Release/vrpc_example')  // <-- compiled c++ addon

// Create an instance of a local (native-addon) vrpc factory
const vrpc = Vrpc(addon)

// Now vrpc is much like a factory, capable to create C++ instances
// and provide you with a proxy for interacting

const proxyOfCppInstance = vrpc.create('Bar')

For all other details, please refer to the documentation of vrpc

Writing a proper binding.gyp

For the binding to work it is important to have a proper binding.gyp:

{
  'variables': {
    'vrpc_path': '<!(if [ -e ../vrpc ]; then echo ../vrpc/vrpc; else echo node_modules/vrpc/vrpc; fi)'
  },
  'targets': [
    {
      'target_name': 'vrpc_example',  # Name of the extension
      'defines': ['VRPC_COMPILE_AS_ADDON=<binding.cpp>'],  # Name of the binding file
      'cflags_cc!': ['-std=gnu++0x', '-fno-rtti', '-fno-exceptions'],
      'cflags_cc': ['-std=c++14', '-fPIC'],
      'include_dirs': [  # Include dirs needing to be found
        '<(vrpc_path)',
        'cpp'
      ],
      'sources': [  # Sources needing to be compiled
        '<(vrpc_path)/addon.cpp',
        'cpp/Bar.cpp'
      ],
      'link_settings': {
        'libraries': [  # System library dependencies, e.g.
          # '-lpthread'
        ],
        'ldflags': [  # Linker flags
          # '-Wl,-rpath,\$$ORIGIN/runtime/path/to/local/lib',
          # '-L<!(pwd)/compiletime/path/to/local/lib'
        ]
      },
    }
  ]
}

Besides compiling sources within your project you can also write a binding.cpp file that works on an existing third-party c++ library. You then only have to link against this library as the comments in the above file indicate.