Introduction to Node.js

Editor's Notes

• #4: Node.js was invented in 2009 by Ryan Dahl, and other developers working at Joyent.[17] Node.js was created and first published for Linux use in 2009. Its development and maintenance was spearheaded by Ryan Dahl and sponsored by Joyent, the firm where Dahl worked.[18] Dahl was inspired to create Node.js after seeing a file upload progress bar on Flickr. The browser did not know how much of the file had been uploaded and had to query the Web server. Dahl desired an easier way.[19] It garnered international attention after its debut at the inaugural European JSConf on November 8, 2009.[20][21][22] Dahl presented Node.js, which combined Google's V8 JavaScript engine, an event-loop, and a low-level I/O API.[17] The project received a standing ovation, and has since then experienced significant growth, popularity and adoption.[17] In 2011, a package manager was introduced for Node.js library, called npm. The package manager allows publishing and sharing of open-source Node.js libraries by the community, and simplifies installation, updating and uninstallation of libraries.[17] In June 2011, Microsoft partnered with Joyent to implement a native Windows version of Node.js.[23] The first Node.js build to support Windows was released in July. In January 2012, Dahl stepped aside, promoting coworker and npm creator Isaac Schlueter to manage the project.[24] In January 2014, Schlueter announced Timothy J. Fontaine would be Node.js's new project lead.[25] In December 2014, Fedor Indutny started io.js, a fork of Node.js. Due to internal conflict over Joyent's governance, io.js was created as an open governance alternative with a separate technical committee.[
• #5: Node.js operates on a single thread, using non-blocking I/O calls, allowing it to support tens of thousands of concurrent connections without incurring the cost of thread context-switching. The design of sharing a single thread between all the requests means it can be used to build highly concurrent applications. The design goal of a Node.js application is that any function performing I/O must use a callback. A downside of this approach is that Node.js doesn't allow scaling with the number of CPU cores of the machine it is running on without using an additional module such as cluster, StrongLoop Process Manager, or pm2. Node.js allows the creation of web servers and networking tools, using JavaScript and a collection of "modules" that handle various core functionality.[17][27][20][28][29] Modules handle File system I/O, Networking (HTTP, TCP, UDP, DNS, or TLS/SSL), Binary data (buffers), Cryptography functions, Data streams, and other core functions.[30][17][28] Node's modules have a simple and elegant API, reducing the complexity of writing server applications.[17][28] Frameworks can be used to accelerate the development of applications, and common frameworks are Express.js, Socket.io and Connect.[17][31] Node.js applications can run on Microsoft Windows, Unix and Mac OS X servers. Node.js applications can alternatively be written with CoffeeScript[32] (a more readable form of JavaScript), Dart or Microsoft TypeScript (strongly typed forms of JavaScript), or any language that can compile to JavaScript.[32] Node.js is primarily used to build network programs such as web servers, making it similar to PHP and Python.[27] The biggest difference between PHP and Node.js is that PHP is a blocking language (commands execute only after the previous command has completed), while Node.js is a non-blocking language (commands execute in parallel, and use callbacks to signal completion).[27] Node.js brings event-driven programming to web servers, enabling development of fast web servers in JavaScript.[17] Developers can create highly scalable servers without using threading, by using a simplified model of event-driven programming that uses callbacks to signal the completion of a task.[17] Node.js was created because concurrency is difficult in many server-side programming languages, and often leads to poor performance.[20] Node.js connects the ease of a scripting language (JavaScript) with the power of Unix network programming.[17] Node.js is built on the Google V8 JavaScript engine, because:[20] V8 is open-source under the BSD license V8 is extremely fast V8 is focused on the web, so is proficient with internet fundamentals like HTTP, DNS, TCP JavaScript is a well-known language within web development, making it accessible to many web developers Thousands of open-source libraries have been built for Node.js, and can be downloaded for free from the npm website. Node.js has a developer community centered around two mailing lists and the IRC channel #node.js on freenode. The community gathers at NodeConf, an annual developer conference focused on Node.js.[
• #6: Bad Use Cases CPU heavy apps Even though I love node.js, there are several use cases where it simply doesn't make sense. The most obvious such case is apps that are very heavy on CPU usage, and very light on actual I/O. So if you're planning to write video encoding software, artificial intelligence or similar CPU hungry software, please do not use node.js. While you can twist and bend things quite a bit, you'll probably get better results with C or C++. That being said, node.js allows you to easily write C++ addons, so you could certainly use it as a scripting engine on top of your super-secret algorithms. Simple CRUD / HTML apps While node.js will eventually be a fun tool for writing all kinds of web applications, you shouldn't expect it to provide you with more benefits than PHP, Ruby or Python at this point. Yes, your app might end up slightly more scalable, but no - your app will not magically get more traffic just because you write it in node.js. The truth is that while we are starting to see good frameworks for node.js, there is nothing as powerful as Rails, CakePHP or Django on the scene yet. If most of your app is simply rendering HTML based on some database, using node.js will not provide many tangible business benefits yet. NoSQL + Node.js + Buzzword Bullshit If the architecture for your next apps reads like the cookbook of NoSQL ingredients, please pause for a second and read this. Yes, Redis, CouchDB, MongoDB, Riak, Casandra, etc. all look really tempting, but so did that red apple Eve couldn't resist. If you're already taking a technological risk with using node.js, you shouldn't multiply it with more technology you probably don't fully understand yet. Sure, there are legitimate use cases for choosing a document oriented database. But if you are trying to build a business on top of your software, sticking to conservative database technology (like postgres or mysql) might just outweigh the benefits of satisfying your inner nerd and impressing your friends. Good Use Cases JSON APIs Building light-weight REST / JSON api's is something where node.js really shines. Its non-blocking I/O model combined with JavaScript make it a great choice for wrapping other data sources such as databases or web services and exposing them via a JSON interface. Single page apps If you are planning to write an AJAX heavy single page app (think gmail), node.js is a great fit as well. The ability to process many requests / seconds with low response times, as well as sharing things like validation code between the client and server make it a great choice for modern web applications that do lots of processing on the client. Shelling out to unix tools With node.js still being young, it's tempting to re-invent all kinds of software for it. However, an even better approach is tapping into the vast universe of existing command line tools. Node's ability to spawn thousands of child processes and treating their outputs as a stream makes it an ideal choice for those seeking to leverage existing software. Streaming data Traditional web stacks often treat http requests and responses as atomic events. However, the truth is that they are streams, and many cool node.js applications can be built to take advantage of this fact. One great example is parsing file uploads in real time, as well as building proxies between different data layers. Soft Realtime Applications Another great aspect of node.js is the ease at which you can develop soft real time systems. By that I mean stuff like twitter, chat software, sport bets or interfaces to instant messaging networks. But please be careful here, since JavaScript is a dynamic / garbage collected language, your response times may sometimes vary depending on how often and long the garbage collection kicks in (at which point your program is stopped). So don't try to build hard realtime systems in node, that require consistent response times. Erlang is probably a better choice for these kinds of applications.