We've finally reached the last chapter of our introductory book to RethinkDB. It's been a long journey so far!
In the previous chapters, you learned how to administer RethinkDB and write and run queries using the ReQL language. You also learned how to administer a cluster, run queries from Node.js, and deploy RethinkDB to the cloud.
In this chapter, we're going to put everything that we've covered together; we'll understand what real-time apps are, how they work, and how to use RethinkDB's features to power a Node.js web application.
In this chapter, you will also learn about the following:
- How to install and use the
Express.jsmodule - How to connect a
Node.jsbackend to a.jsfrontend - How to use Changefeeds to push data to the client
At the end of the chapter, you'll have a perfectly working Node.js web application that you can use as a template when developing your own web apps. We'll also have a brief recap of the most important things that we've covered.
In this chapter, we're going to see how we can use the tools we've covered so far to build real-time applications for the Web. However, before diving into it, one of the first questions you may want answered is, "what exactly is a real-time web application?"
A real-time web application can be defined as any kind of web-facing software that allows clients (usually users) to receive information as soon as it gets published. In other words, it's a software application that functions within a timeframe that the user senses as immediate or current. In these types of software, latency must be extremely low, usually in the range of milliseconds.
You may be wondering what a real-time web app looks like. Well, chances are that you use one of them every day! Gmail is an example of a real-time web app; we've all noticed e-mails and notifications popping up on our browser in real time and an asynchronous manner without the need of refreshing the page. Twitter is another example: tweets appear as soon as they get published without the user needing to refresh the browser page. Many multiplayer online games depend on low-latency communications between individual gamers, and for this reason technologies must be used to get the data to clients in real time; so online games are another example of real-time applications. Charts and graphs have always been a great way to visualize data in a graphical manner. Now, you can have these graphs and charts connected to real-time data sources, such as a feed or a database, and you can see changes reflected on the graphs in real time. If you think about it, the possibilities are literally endless!