Over the years, we have seen several revolutions, and shifts in paradigms spanning from mainframes to x86 farms, from heavyweight methodologies to lightweight agile methods, and from desktop and thick clients to thin, rich, and highly available web applications and ubiquitous computing.
With the advancements and changes in the technology landscape going towards smaller, more portable, and lightweight devices and the devices being used widely for day-to-day activities, the need to push the computation from the client machines to the backend grows to an even more prominent one. This also brings forth opportunities and challenges involved in developing applications with near real-time or real-time event and data propagation between servers and clients; that is where HTML 5 provides developers with the standards, API, and flexibility required to achieve the same result in web applications that is achievable in thick desktop applications.
The communication between clients and the servers has turned to the most fundamental subject both in terms of quantity, content, interoperability, and scalability of these interactions. The XML era, long waiting requests, single browser, and single device compatibility is over; instead the era of devices, multiple clients, and browsers, from very small devices capable of only processing text over HTTP to mammoth scale machines processing almost any kind of content has begun. With this said, producing the content and accepting the content along with the ability to switch between older and newer protocols has turned into an obvious must.
Java EE 7 comes with more emphasis on these emerging (and dominating) requirements; support for HTML5, more asynchronous communication/invocation-capable components, and support for JSON as one of the data formats have arrived to help developers with resolving the technical requirements and giving the developers ample time to work on the business requirements' implementation of their systems.
This book is an attempt to provide the avid technologists with an overview of what Java EE is in general and Java EE 7 in particular, as a technology platform, provides for developing lightweight, interactive applications based on HTML5 deployable in any Java EE compatible container.
Chapter 1, Building RESTful Web Services Using JAX-RS, starts with the basic concepts of building RESTful Web Services and covers JAX-RS 2.0 API, detailing the different annotations, Providers, MessageBodyReader, MessageBodyWriter, Client API, and Bean Validation support in JAX-RS 2.0.
Chapter 2, WebSockets and Server-sent Events, discusses the different programming models for sending near real-time updates to clients. It also covers WebSockets and Server-sent Events, the JavaScript and Java API for WebSockets and Server-sent Events. This chapter compares and contrasts WebSockets and Server-sent Events and shows the advantages of WebSockets to reduce unnecessary network traffic and improve the performance.
Chapter 3, Understanding WebSockets and Server-sent Events in Detail, covers the Java EE 7 API for WebSockets, Encoders and Decoders, the Client API, how to send different kinds of messages with WebSockets using blobs, and ArrayBuffers. It teaches how to secure a WebSockets-based application. It outlines the best practices for WebSockets and Server-sent Events-based applications.
Chapter 4, JSON and Asynchronous Processing, covers the Java EE 7 JSON-P API for parsing and manipulating JSON data. It also discusses the new NIO API introduced in Servlet 3.1 specification. It teaches how to use the JAX-RS 2.0 API for asynchronous request processing to improve scalability.
Chapter 5, RESTful Web Services by Example, covers two real-life examples of RESTful Web Services. It covers an event notification sample based on the Twitter Search API, how the server can push the data to clients as and when events occur. A library application ties the different technologies covered in the above chapters together.
To be able to build and run samples provided with this book you will need:
Apache Maven 3.0 and higher. Maven is used to build the samples. You can download Apache Maven from http://maven.apache.org/download.cgi
GlassFish Server Open Source Edition v4.0 is the free, community-supported Application Server providing implementation for Java EE 7 specifications. You can download the GlassFish Server from http://dlc.sun.com.edgesuite.net/glassfish/4.0/promoted/
This book is a perfect reading source for application developers who are familiar with Java EE and are keen to understand the new HTML5-related functionality introduced in Java EE 7 to improve productivity. To take full advantage of this book, you need to be familiar with Java EE and have some basic understanding of using GlassFish application server.
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: "The request, which is sent to the JAX-RS resource, is a POST request with app/library/book/ as the target URI."
A block of code is set as follows:
@GET
@Path("browse")
public List<Book> browseCollection() {
return bookService.getBooks(); }When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:
@GET @Path("browse") public List<Book> browseCollection() { return bookService.getBooks(); }
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 a user clicks on the Hold button on the HTML page".
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