Node.js has a modular architecture with the V8 engine providing JavaScript execution and libuv handling asynchronous operations. Core modules can be implemented in either C++ or JavaScript. When a module is required, Node.js checks its cache and compiles the source before returning the exports object. This allows seamless usage of both native and JavaScript modules.

1. Trace Node.js
gd

2. Node.js - Architecture
v8 libuv
C++ binding modules
Js native modulesjavascript
C++

3. Outline
• libuv
• V8
• Node.js modules

4. libuv
• libuv enforces an asynchronous, event-driven style
of programming

5. Libuv – hollow world
• Callback

6. V8
• V8 provides C++ API
o Access Javascript object in C++
o Access C++ objects in Javascript

7. Terms
• Handler: An object reference managed by
the v8 garbage collector
• HandlerScopes: A stack-allocated class that
governs a number of local handles
• Context: A sandboxed execution context
with its own set of built-in objects and
functions
• Templaates: A template is a blueprint for
JavaScript functions and objects in a
context.

8. Samples
• Samples/shell.c
o Main()
o CreateShellContext()

9. Core modules
• C++ modules (src/node_extensions.cc)
o fs
o http_parser
o os
o Zlib
o …
• Js modules (lib/)
o fs.js
o http.js
o net.js
o os.js
o modules.js
o …

10. How to use core modules ?
…
var util = require('util');
var pathModule = require('path');
var binding = process.binding('fs');
var constants = process.binding('constants');
var fs = exports;
…
Lib/fs.js

11. How modules inited ?
node::Start(argc, argv)
// Use original argv, as we're just copying values out of it.
Handle<Object> process_l = SetupProcessObject(argc, argv);
v8_typed_array::AttachBindings(context->Global());
// Create all the objects, load modules, do everything.
// so your next reading stop should be node::Load()!
Load(process_l);
// All our arguments are loaded. We've evaluated all of the scripts. We
// might even have created TCP servers. Now we enter the main eventloop. If
// there are no watchers on the loop (except for the ones that were
// uv_unref'd) then this function exits. As long as there are active
// watchers, it blocks.
uv_run(uv_default_loop(), UV_RUN_DEFAULT);

12. C++ modules
• What process.binding (a.k.a Node::Binding)
do
o Check binding_cache if module is in cache
already
o If not cached, call node_extensions::get_builtin_module to
bind the c++ module and call the module’s
register_func()
• How C++ modules implemented
o node_file.cc

13. Js modules
• When when requiring a js module in native modules,
NativeModule.require() in node.js is called
o If require(“native_module”), return NativeModule
o If cached return getCached().exports
o else return new
NativeModule(id).compile().exports
• NativeModule(id).compile() reads
source and compiles source into js
object in js heap

14. Why NativeModule.require()
• src/node.js is invoked by node::Load() in src/node.cc, and
responsible for loading lib/*.js and bootstrapping the nodejs
core.
NativeModule.wrap = function(script) {
return NativeModule.wrapper[0] + script + NativeModule.wrapper[1];
};
NativeModule.wrapper = [
'(function (exports, require, module, __filename, __dirname) { ',
'n});'
];
NativeModule.prototype.compile = function() {
var source = NativeModule.getSource(this.id);
source = NativeModule.wrap(source);
var fn = runInThisContext(source, this.filename, true);
fn(this.exports, NativeModule.require, this, this.filename);
this.loaded = true;
};

15. How to use core modules(revisit)
• Loading C++ module
process.binding(“fs”) -> get_builtin_module(“fs”) ->
NODE_MODULE(node_fs, node::InitFs)
• Loading js module
Require(“path”) -> NativeModule.require(“path”) ->
process.binding("natives")["path"] ->
DefineJavaScript() -> natives[] -> node_natives.h

16. More !!
• How to write a C++ module
o http://nodejs.org/api/addons.html
• How about user-defined js module
o lib/modules.js
o http://nodejs.org/api/modules.html

17. Ref
• 深入浅出Node.js, http://vdisk.weibo.com/s/G-
kaugh6Z1f6
• Node.js源码研究之模块组织加载,
http://developer.51cto.com/art/201109/290287.htm
• http://nikhilm.github.io/uvbook/basics.html
• https://developers.google.com/v8/embed