Nodejs overview
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Node.js is a JavaScript runtime built on Chrome's V8 engine that allows JavaScript code to be run outside of a browser. It introduces asynchronous and event-driven programming to JavaScript. Native addons allow integrating C/C++ code and libraries into Node.js applications for performance reasons or to interface with legacy code. The N-API provides a stable API for building native addons that is compatible across Node.js versions to avoid breakage. Examples demonstrate how to create asynchronous native addons that interface between JavaScript and C++ code.
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Nodejs overview
- 1. Node.js: a little overview Nicola Del Gobbo
- 2. Who am I? Developer N-API Team Full stack developer highly focused on performance How to implement a native addon for Node.js with programming languages different from C or C++ My research field
- 3. Agenda Introduction to Node.js How to create distributed services Native Addons
- 5. What can I do with Node.js? Everything Great thank to Node.js Community and Working Groups Packages 963,619 Downloads - Last Week 10,822,198,617 Downloads - Last Month 48,577,378,041
- 6. CLI APPLICATION DESKTOP APPLICATIONDISRTRUBUTED SYSTEM REAL TIME SYSTEM What can I do with Node.js?
- 7. Release
- 9. Choose your modules Add health checking Track your requests Power your metrics Build your Docker image Deploy to Kubernetes
- 10. What is Node.js? A JavaScript engine Asynchronous I/O ~100k LOC of JS and C++ Node is a glue Node.js is a JavaScript runtime built on Chrome's V8 JavaScript engine
- 12. JavaScript “The world's most misunderstood programming language“ Douglas Crockford
- 13. JavaScript • let and const • Better Unicode support • Template literals • Arrow function • Default parameters • Spread operator • Class • Destructuring • Symbols • Sets and Maps • Iterator • Generator • Promise • Async / Await • Async Iterator • Proxy API • Reflection API ES2015 ES2016 ES2017 ES2018 ES2019
- 14. JavaScript “Use JavaScript like JavaScript“ “JavaScript developers should focus on writing idiomatic, readable and maintainable code“ Peter Marshall & Arunesh Chandra
- 15. CONCURRENCY MODEL? Asynchronous I/O Single threaded by default Worker Threads from Node.js v10.5.0 Execution never stop Don’t block the event loop
- 16. Synchronous model? Blocking the whole process or you need to have multiple execution stacks
- 17. Asynchronous model? The main process is never blocked. No strategy is required to handle competing requests
- 18. The event loop
- 19. Asynchronous in low level
- 20. Asynchronous in low level
- 21. CommonJS Module ES6 Module from v8.5.0 “Se non hai provato Node.js non sai cos’è la modularità e il riuso” Matteo Collina Modularity
- 22. Modularity
- 23. Modularity
- 24. EventEmitter is a very important class in Node.js. It provides a channel for events to be dispatched and listeners notified. Many objects you will encounter in Node.js inherit from EventEmitter Events
- 26. Events
- 27. Event bus
- 28. Event bus
- 29. Stream • Buffer: data structure to store and transfer arbitrary binary data • Stream: abstract interface for working with streaming data
- 30. Stream vs Buffer • Streams keep a low memory footprint even with large amounts of data • Streams allow you to process data as soon as it arrives
- 32. Use http core
- 33. Frameworks
- 34. Express Downloads - Last Week 7,495,349 Downloads - Last Month 33,248,650
- 35. • Minimalist • Unopinionated • Fast (about 38k req/sec) • Simple (do one thing well philosophy from Unix world) • Wrapper of http core module Express
- 37. • Middleware • Error handler • Router • Views / template engine Express milestones
- 38. It’s always a question to manipulate the Request and Response object Middlewares
- 39. Middlewares
- 40. Use middlewares
- 43. Error handler
- 44. Routing refers to determining how an application responds to a client request to a particular endpoint, which is a URI (or path) and a specific HTTP request method Routing
- 45. The fastest JSON Schema validator for Node.js and browser Validate your input
- 46. Pug - Mustache - Dust - Nunjuks - EJS Views / template engine
- 47. Helmet helps you secure your Express apps by setting various HTTP headers Security
- 48. Log everything that happens in your application Pay attention there is a cost for logging Logger Winston
- 49. What is Node.js Native Add-on? C / C++ code called from JavaScript BRIDGE Native environment JavaScript
- 50. From Node.js documentation Node.js Addons are dynamically-linked shared objects, written in C++, that can be loaded into Node.js using the require() function, and used just as if they were an ordinary Node.js module. They are used primarily to provide an interface between JavaScript running in Node.js and C/C++ libraries.
- 51. Why? Performance In general C / C++ code performs better than JavaScript code, but it’s not always true. Image processing (in average 6 times faster) Video processing CRC cyclic redundancy check (in average 125 times faster) Compression Scientific calculus Algorithms that execute CPU heavy tasks
- 52. Why? Integrate legacy application You have the source code of an old C / C++ application and want to expose something of its functionalities
- 53. Why? You don’t find what fits your specific needs on npm Sometimes completely implementing the module in JavaScript is not the right solution Think at libraries like: ImageMagick Ghostscript FFmpeg TensorFlow …
- 54. Why? Better error handling Even if you will use an old C / C++ library you will get an error code that explains the error that just happened In new C / C++ library you have the exception You don’t have to parse some string to identify if there was an error and what kind of it
- 55. With great power comes great responsibility Ben Parker
- 56. Problems Fragmentation API The API to implement native add-ons has been changed across different version of Node.js Most of the changes were on V8 API and ObjectWrap API 0.8 - 0.10.x - 0.12.x - 1.x - 2.x - 3.x - 4.x - 5.x - 6.x - 7.x - 8.x - 9.x - 10.x - 11.x - 12.x For more info http://v8docs.nodesource.com/
- 57. Problems Need an adapter to stay compatible across different version of Node.js • NAN - Native Abstraction for Node.js • API compatibility • Strong bonded with V8 API • You have to recompile your native add-ons switching to different version of Node.js
- 59. Node.js: 6.12.2 V8: 5.1.281 NODE_MODULE_VERSION: 48 Addon
- 60. Node.js: 8.9.3 V8: 6.1.534 NODE_MODULE_VERSION: 57 ABI break • At worst, mysterious segfaults • At best, addon fails to load • NODE_MODULE_VERSION mismatch
- 61. Problems Write portable C / C++ code Your native code must compile and run on different: ARCHITECTURE PLATFORM COMPILER
- 62. Problems Documentation • C / C++ libraries that you are integrating are not well documented • There are good references but not so much practical guide focusing on complex concepts about native add-ons
- 63. N-API • Kicked off in VM Summit April 2016 • Dual implementation from the start (V8 / ChakraCore) • EPS Dec 2016 https://github.com/nodejs/node-eps/blob/master/005- ABI-Stable-Module-API.md • First half of 2017 - refinement and backporting module • May 2017 experimental release in Node.js 8 • VM Summit July 2017 – Exit criteria agreed • N-API leaves experimental status March 14 2018 • Backported to all LTS release • Improve core and C++ Wrapper (node-addon-api) • Create ecosystem
- 64. N-API • N-API is C whereas node-addon-api is C++ • node-addon-api not thechnically part of ABI stable API • Helper to simplify code using C++ • All inline • Only depends on export N-API C functions
- 66. node-addon-api vs NAN • Same • Includes C++ wrapper • Provides common helper functionality • Reduces likelihood of needing to change code for new Node.js versions • Different • Does not use V8 Types • Not tied to a specific JavaScript engine • Preserves compile once/ run multiple versions from N-API • Reduces even further likelihood of having to change code
- 67. Node.js: no matter V8/ChakraCore: no matter NAPI_VERSION: 1
- 68. Node.js: later V8/ChakraCore: no matter NAPI_VERSION: 2 No ABI break • NAPI_VERSION is cumulative • Addon is forwards compatible
- 69. How to organize your project
- 70. Example: the JavaScript part
- 71. Example: the JavaScript part
- 73. Example: the C / C++ part
- 74. Example
- 77. Example
- 78. Asynchronous code Preserve reference to function we want call Create worker threads using libuv Handle the results
- 79. AsyncWorker
- 80. AsyncWorker
- 81. Example
- 82. AsyncWorker You cannot call JavaScript function from the Worker Thread until this PR will be landed
- 83. • ObjectWrap is a way to expose your C++ code to JavaScript • You have to extend ObjectWrap class that includes the plumbing to connect JavaScript code to a C++ object • Classes extending ObjectWrap can be instantiated from JavaScript using the new operator, and their methods can be directly invoked from JavaScript • Unfortunately, the wrap part really refers to a way to group methods and state • It’s your responsibility write custom code to bridge each of your C++ class methods. ObjectWrap API
- 84. Example
- 85. Thanks Don’t be afraid sometimes it’s a good thing dirty your hands with a little of C++ All examples and materials are here https://github.com/NickNaso/node-overview
Editor's Notes
- #5: Update the numbers
- #6: Update the numbers
- #50: In a very simple way Native Addons could be considered as C / C++ code called from JavaScript. They are a bridge between our Application programming language JavaScript and Native environment that is completely written in C / C++. This allow us to call C / C++ functions and methods directly from JavaScript.
- #51: If we take a look at Node.js documentation under Addons section Native Addons are defined as: dynamically-linked shared objects, written in C++, that can be loaded into Node.js using the require() function, and used just as if they were an ordinary Node.js module Their main purpose is to provide an interface between JavaScript running in Node.js and C / C++ libraries. This increase the developer experience because if you are using a Native Addon you don’t care of this, but you just use it as any other pure JavaScript module.
- #52: Why should you implement new Native Add-On? The first reason is for performance In general C / C++ code performs better then JavaScript code, but it’s really true for CPU bounds operations. Think for example at: Image processing | Video processing | Compression | Scientific calculus | Cyclic redundancy check and all algorithms that at one point execute some CPU heavy tasks. In all these cases you can gain more in performance.
- #53: Sometimes you want just integrate a legacy application So you have the source code of an old C / C++ application and want to expose something of its functionalities through new Node.js application
- #54: Even if npm is a very large repo where you can find almost everything sometimes you don’t find what fits your specific needs and in this case you have to take a choice. Completely reimplementing the module in JavaScript, but in my opinion it’s an insane idea to reimplement from the ground solutions like ImageMagick | Ghostscript | Ffmpeg and TensorFlow because you will lose all your time on develop a module and not to concentrate on business logic of your application. In these cases the You have to concentrate on business logic of your application and not on developing a single module
- #64: N-API is one of the most important features announced with Node.js 8 which is aimed at reducing the maintenance cost for native add-ons
- #65: N-API is one of the most important features announced with Node.js 8 which is aimed at reducing the maintenance cost for native add-ons
- #66: N-API is one of the most important features announced with Node.js 8 which is aimed at reducing the maintenance cost for native add-ons
- #67: N-API is one of the most important features announced with Node.js 8 which is aimed at reducing the maintenance cost for native add-ons
- #68: N-API is one of the most important features announced with Node.js 8 which is aimed at reducing the maintenance cost for native add-ons
- #69: N-API is one of the most important features announced with Node.js 8 which is aimed at reducing the maintenance cost for native add-ons
- #70: When I start to develop a new native addon I use the boilerplate depicted on the slide. Here the most important elements are the SRC and LIB folders. SRC folder contains the C / C++ code and the native dependencies while the LIB folder contains the JavaScript code There are also the usual package.json file and the binging.gyp file that contains all the building configurations for the addon. At the end our addon will be composed by two parts one written in C++ and another written in JavaScript and usually the JavaScript part will use the native code to expose some features
- #71: When I start to develop a new native addon I use the boilerplate depicted on the slide. Here the most important elements are the SRC and LIB folders. SRC folder contains the C / C++ code and the native dependencies while the LIB folder contains the JavaScript code There are also the usual package.json file and the binging.gyp file that contains all the building configurations for the addon. At the end our addon will be composed by two parts one written in C++ and another written in JavaScript and usually the JavaScript part will use the native code to expose some features
- #72: When I start to develop a new native addon I use the boilerplate depicted on the slide. Here the most important elements are the SRC and LIB folders. SRC folder contains the C / C++ code and the native dependencies while the LIB folder contains the JavaScript code There are also the usual package.json file and the binging.gyp file that contains all the building configurations for the addon. At the end our addon will be composed by two parts one written in C++ and another written in JavaScript and usually the JavaScript part will use the native code to expose some features
- #73: In our binding.gyp we need to set the target name that will match the module name. The reported example is almost simple sometimes finding the right settings for binding.gyp is not easy so I suggest to take a look at GYP documentation or at nodey-gyp wiki where there are examples of existing binding.gyp and use them as source of inspiration to solve your problems with these kind of configurations.
- #74: What happen here? The macro NODE_API_MODULE creates code that will register a module named ”echo” and in addition it will ensure that a function init is called when the module is required. In the init we export our function or object. In the reported example we export echo and you can find the code executed by this function in the method Echo. As first thing we validate the input data, then transfer the JavaScript input to C++ data structure. C++ code perform the requested computation and before returning transfer the output data to JavaScript context. This is the most straightforward integration pattern that you can realize to pass data between JavaScript and C / C++ . The main reason for using this approach is simplicity and because you can integrate the C++ without modification. In addition we have a complete decoupling of the JavaScript and C++ code.
- #77: In an asynchronous addon function, the calling JavaScript code returns immediately. The calling code passes a callback function to the addon, and the addon does its work in a separate worker thread. This avoids locking up the Node.js event loop, as the addon function does not block.