JavaScript Object Notation (JSON) has rapidly become the lingua franca for structured document exchange on the Web, outpacing XML in many domains. Three of the reasons for this are obvious: it plays well with JavaScript, it's simple, and it just works. However, there are other reasons for its success as well. As you'll see in the pages of this book, it's supported by a wide variety of languages and libraries, making it easy to use in all kinds of scenarios.
In this book, I provide recipes for common uses of JSON. You're welcome to read the book from cover to cover, seeing all the ways JSON can be used in building web and standalone applications. However, it's organized as a cookbook, so that you can quickly go to the chapter or recipe that addresses a particular problem you might want to solve with JSON now. I recommend skimming this preface to see what's where, taking a quick look at Chapter 1, Reading and Writing JSON on the Client, or Chapter 2, Reading and Writing JSON on the Server, depending on your interest, and then jumping right to the recipes that interest you the most.
Chapter 1, Reading and Writing JSON on the Client, gives you recipes to read and write JSON in a number of client environments, including JavaScript, C#, C++, Java, Perl, and Python.
Chapter 2, Reading and Writing JSON on the Server, goes the other way, looking at JSON on typical server-side languages such as Clojure, C#, Node.js, PHP, and Ruby. Of course, you can write client-side applications with these languages, as well, just as you can write a server in C# or Java. So the division of recipes between these chapters is somewhat arbitrary; pick a language and dive in!
Chapter 3, Using JSON in Simple AJAX Applications, shows you how to apply JSON for data exchange with today's browsers.
Chapter 4, Using JSON in AJAX Applications with jQuery and AngularJS, discusses how to use JSON with two popular web frameworks, jQuery and Angular.
Chapter 5, Using JSON with MongoDB, shows you how MongoDB, a popular NoSQL database, uses JSON for its stored document format and gives you recipes to use MongoDB as a REST service in your web applications.
Chapter 6, Using JSON with CouchDB, shows you how CouchDB, another popular NoSQL database, uses JSON and how you can use CouchDB as a standalone REST service in your web applications.
Chapter 7, Using JSON in a Type-safe Manner, looks at how you can adapt the type-free nature of JSON with the type safety provided by languages such as C#, Java, and TypeScript to reduce programming errors in your application.
Chapter 8, Using JSON for Binary Data Transfer, shows you how, even though JSON is a text-based document format, you can still use it to move binary data around if you have to do so.
Chapter 9, Querying JSON with JSONPath and LINQ, has recipes on how you can write queries against JSON documents to obtain just the slice of data you're looking for. This is especially powerful when combined with the recipes from Chapters 5, Using JSON with MongoDB, and Chapter 6, Using JSON with CouchDB.
Chapter 10, JSON on Mobile Platforms, shows you recipes for using JSON in mobile applications that use Android, iOS, and Qt.
Unlike many other technical books, this one focuses on a wide variety of supporting technologies in its examples. I don't expect that you'll have experience or the tools to try every example in this book, especially right away. However, it's helpful to have a few things set out.
You should have some programming experience, preferably in JavaScript. Unless a recipe is targeted at a specific programming language such as C#, the recipes in this book are written in JavaScript. I do this for two reasons. Firstly because the "J" in JSON stands for JavaScript (even though it's widely applicable to other languages), and, in this day and age, every programmer should have at least a nodding familiarity of JavaScript.
As far as software environments go, to begin with, you should have access to a good web browser such as Chrome or a recent version of Safari, Firefox, or Internet Explorer. You can use the JavaScript runtime in any of these browsers to experiment with JSON and get started.
Secondly, a lot of the client-server examples feature Node.js. I picked Node.js for server-side example programming because it's also JavaScript, meaning that you don't have to jump through different language syntaxes as you move between the client and server. Node.js runs well on Windows, Mac OS X, and Linux, too, so you shouldn't have a problem setting it up.
If you're interested in using JSON with databases, CouchDB or MongoDB are your best choices and I discuss both of them in this book. Which one you choose is really a matter of your domain and personal preference. I've been using MongoDB for 5 years on various projects but have recently taken a liking to some of CouchDB's features and its integrated support for RESTful services.
Finally, if you're a Microsoft developer, you may want to take special note of the C# examples that use Newtonsoft's Json.NET throughout this book. Json.NET is what JSON in C# ought to be, and it's definitely worth your attention.
If you're writing applications that move structured data from one place to another, this book is for you. This is especially true if you've been using XML to do the job because it's entirely possible that you could do much of the same work with less code and less data overhead in JSON.
While the book's chapters make some distinction between the client and server sides of an application, it doesn't matter if you're a frontend, backend, or full-stack developer. The principles behind using JSON apply to both the client and the server, and in fact, developers who understand both sides of the equation generally craft the best applications.
In this book, you will find several headings that appear frequently (Getting ready, How to do it, How it works, There's more, and See also).
To give clear instructions on how to complete a recipe, we use these sections as follows:
This section tells you what to expect in the recipe, and describes how to set up any software or any preliminary settings required for the recipe.
This section usually consists of a detailed explanation of what happened in the previous section.
This section consists of additional information about the recipe in order to make the reader more knowledgeable about the recipe.
In this book, you will find a number of text styles 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: "Let's look at loads and dumps further."
A block of code is set as follows:
function doAjax() {
var xmlhttp;
if (window.XMLHttpRequest)
{
// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
}When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:
function doAjax() {
var xmlhttp;
if (window.XMLHttpRequest)
{
// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
}Any command-line input or output is written as follows:
# cp /usr/src/asterisk-addons/configs/cdr_mysql.conf.sample /etc/asterisk/cdr_mysql.conf
New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: " Then, you'll want to go to More Tools | JavaScript console."
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