Fault tolerant applications in nodejs - blog. At Nodejitsu, our node.js hosting platform deals with 1000s of live servers spanned across multiple data-centers. As scale increases, minute statistical probabilities become very real problems. The network is unreliable, disks become unwritable, streams break, unexpected input is unexpected, and entire data-centers can go down. Think of it like this: If you have 1,000 servers each individually rated at 99.9% uptime, on average, one of those machines is always failing. So we research... Fault tolerant system Fallacies of Distributed Computing Properties of distributed systems High availability Percentage calculation and we research more... Shared nothing architecture Byzantine fault tolerance Eventually, we hit the The Halting Problem: Given a description of a computer program, decide whether the program finishes running or continues to run forever. To summarize all of these links in the context of this blog post...
Basic strategies in building fault tolerant applications in node Hook.io Basic Paxos. The Tapir's Tale: A Not Very Short Introduction To Node.js. Node.js is a set of asynchronous libraries, built on top of the Google V8 Javascript Engine. Node is used for server side development in Javascript. Do you feel the rush of the 90's coming through your head. It is not the revival of LiveWire, Node is a different beast. Node is a single threaded process, focused on doing networking right. The graph for memory usage is even better. Read more about it at the Web Faction Blog OK, so what's the catch? // Synchronous var result = db.query("select * from T"); // Use result // Asynchronous db.query("select * from T", function (result) { // Use result }); So, all libraries that deal with IO has to be re-implemented with this style of programming.
History Node is definitely not the first of its kind. Twisted appeared in Python (2002) and EventMachine in Ruby (2003). This year a couple of newcomers appeared. Get Started This example uses OSX as an example platform, if you use something else you will have to google for instructions. Networking Modules !!! 10 Vital Aspects of Building a Node.JS Application — Engineering. Purpose It sounds antagonisingly obvious, but the same goes for everything you decide to build. Your app needs to have purpose. A job to do. A problem to solve. Solid reasoning here will cement durable foundations for the application itself. Structure Structure concerns source code layout, file arrangement, library/module usage and on the whole describes the way the application has been weaved together.
Modularity. Deployment Your method of shipping applications to production can vary greatly depending on the nature of your stack. Manually SSH’ing into servers and cloning the git repository. This is by no means an exhaustive list of deploy methods, and you may need to be a bit creative to come up with a solution to best fit your needs. Configuration Virtually every application has constants and settings that will need to be changed at convenience. I used to just dump configuration settings into a file that exported an object of configuration properties. Logs, Metrics and Monitoring Logs. Creating chat roulette with node.js, socket.io, and OpenTok » TokBox Developers Blog. This tutorial will create a simple chat roulette app using node.js, socket.io and OpenTok.
Socket.io allows us to pass data between clients in real-time using only javascript and eliminate the need for a database. OpenTok allows us to quickly publish and subscribe to webcam streams without having to worry about server requirements and bandwidth usage — all we have to do is implement a simple and free javascript API. Here is a high-level overview of the application architecture: You can check out the app running here: You can view the GitHub repo here: The Setup If you don’t already have node.js and npm (node package manager), install them now. The first thing we want to do is install express. Once express is installed, use the following commands to create the application we are going to build: This command create a new directory called RouletteTok that contains the basic structure of our application.
The Application app.js. Building Real-time CoffeeScript Web Applications With SocketStream. Our engineering team at Aol Europe have been working on a number of exciting new projects over the past few months including a brand new high-performance real-time web framework called SocketStream.We're going to take a first look at how you can start building applications with it today. The brain-child of software engineer Owen Barnes, SocketStream is built on top of node.js, resolves around the popular single-page application (SPA) paradigm and utilizes HTML5 WebSockets, Socket.IO, Redis and other techologies to provide an extremely responsive experience for the web. It's effectively a complete-stack for all of your client and server development needs. The team launched SS at Hacker News London this week and we were humbled by the positive reaction on both GitHub (where we very surprisingly became the trending repo of the week) and Twitter including some interest from Jeremy Ashkenas, the developer behind Backbone.js, Underscore.js and of course, CoffeeScript.
Understanding WebSockets.