Book Image

Advanced Express Web Application Development

By : Andrew Keig
Book Image

Advanced Express Web Application Development

By: Andrew Keig

Overview of this book

Building an Express application that is reliable, robust, maintainable, testable, and can scale beyond a single server requires a bit of extra thought and effort. Express applications that need to survive in a production environment will need to reach out to the Node ecosystem and beyond, for support.You will start by laying the foundations of your software development journey, as you drive-out features under test. You will move on quickly to expand on your existing knowledge, learning how to create a web API and a consuming client. You will then introduce a real-time element in your application.Following on from this, you will begin a process of incrementally improving your application as you tackle security, introduce SSL support, and how to handle security vulnerabilities. Next, the book will take you through the process of scaling and then decoupling your application. Finally, you will take a look at various ways you can improve your application's performance and reliability.
Table of Contents (14 chapters)
Advanced Express Web Application Development
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Error handling, domains, and crash-only design


The Node community has embraced a crash-only design pattern, which simply means this: if you get an uncaught exception, catch it, log it, and restart the process. Crash-only design and domains work quite well as a pattern, particularly if your application is using cluster. Let's make a change to our cluster module, ./lib/cluster/index.js, on vision-core. Here, we include the domain module; instead of simply including our module to run in a cluster, we create a domain and call the run method. We then include a domain-based error handler that logs and then closes the process via process.exit(1). The cluster exit handler will pick this up and fork a new process:

var cluster = require('cluster')
, http = require('http')
, numCPUs = require('os').cpus().length
, logger = require('../logger')
, domain = require('domain');

function Cluster() {}

Cluster.prototype.run = function(module) {
  if (cluster.isMaster) {
    for (var i = 0; i < numCPUs...