Node provides a set of tools that help in the design and maintenance of large-scale network applications facing the C10K problem. In this chapter we've taken our first steps into creating network applications with many simultaneous clients, tracking their session information and their credentials. This exploration into concurrency has demonstrated some techniques for routing, tracking, and responding to clients. We've touched on some simple techniques to use when scaling, such as the implementation of intra-process messaging via a publish/subscribe system built using a Redis database.
We are now ready to go deeper into the design of real-time software—the logical next step after achieving high concurrency and low latency by using Node. We will extend the ideas outlined during our discussion of long polling and place them in the context of more robust problems and solutions.