Summary

Experienced developers have all struggled with the problems that Node aims to solve:

• How to serve many thousands of simultaneous clients efficiently
• Scaling networked applications beyond a single server
• Preventing I/O operations from becoming bottlenecks
• Eliminating single points of failure, thereby ensuring reliability
• Achieving parallelism safely and predictably

As each year passes, we see collaborative applications and software responsible for managing levels of concurrency that would have been considered rare just a few years ago. Managing concurrency, both in terms of connection handling and application design, is the key to building scalable architectures.

In this chapter, we've outlined the key problems Node's designers sought to solve, and how their solution has made the creation of easily scalable, high-concurrency networked systems easier for an open community of developers. We've seen how JavaScript has been given very useful new powers, how its evented model has been extended, and how V8 can be configured to further customize the JavaScript runtime. Through examples, we've learned how I/O is handled by Node, how to program the REPL, as well as how to manage inputs and outputs to the process object. 

Node turns JavaScript into a systems language, creating a useful anachronism of scripting sockets as well as buttons, and cutting across decades of learning from the evolution of computing.

Node's design restores the virtues of simplicity the original Unix developers discovered in the 1970s. Interestingly, computer science rebelled against that philosophy in the intervening time period. C++ and Java favored object-oriented design patterns, serialized binary data formats, subclassing rather than rewriting, and other policies that caused codebases to often grow to one million lines or more before finally collapsing under the weight of their own complexity.

But then came the web. The browser's View, Source feature is a gentle on-ramp that brought millions of web users into the ranks of a new generation of software developers. Brendan Eich designed JavaScript with this novice prospective developer in mind. It's easy to start by editing tags and changing styles, and soon be writing code. Talk to the young employees of newly growing start-ups, now professional developers, engineers, and computer scientists, and many will recount View, Source as how they got their start.
Riding Node's time warp back, JavaScript found a similar design and philosophy in the founding principles of Unix. Perhaps connecting computers to the internet gave smart people new, more interesting computing problems to solve. Perhaps another new generation of students and junior employees arrived and rebelled against their mentors once again. For whatever reason, small, modular, and simple make up the prevailing philosophy today, as they did much earlier before.

In the decades ahead, how many more times will computing technology change enough to prompt the designers of the day to write new software and languages quite different from the practices taught and accepted as correct, finished, and permanent just a few years earlier? As Arthur C. Clarke noted, trying to predict the future is a discouraging and hazardous occupation. Perhaps we'll see several more revolutions in computers and code. Alternatively, it's possible that computing technology will soon plateau for a stretch of years, and within that stability, computer scientists will find and settle on the best paradigms to teach and use. Nobody knows the best way to code right now, but perhaps soon, we will. If that's the case, then this time now, when creating and exploring to find these answers is anyone's game, is a wonderfully compelling time to be working and playing with computers.

Our goal of demonstrating how Node allows applications to be intelligently constructed out of well-formed pieces in a principled way has begun. In the next chapter, we will delve deeper into asynchronous programming, learn how to manage more complex event chains, and develop more powerful programs using Node's model.