In this book, you will find a number of styles of text that distinguish between different kinds of information. Here are some examples of these styles, and an explanation of their meaning.

Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "We can include our custom JavaScript library located in the mylib.js file."

A block of code is set as follows:

-module(sigserver_app).
-behaviour(application).
-export([start/2, stop/1, start/0]).
start() ->
    ok = application:start(ranch),
    ok = application:start(crypto),
    ok = application:start(cowlib),
    ok = application:start(cowboy),

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

private static Map<Integer,Set<WebSocket>> Rooms = new HashMap<>();
    private int myroom;
    public Main() {
        super(new InetSocketAddress(30001));
    }

Any command-line input or output is written as follows:

rebar create-app appid=sigserver

New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: "When the customer enters a message and clicks on the Submit query button, we will wrap the message into a JSON object and send it via the data channel."