The Web allows you to make applications that can be used from anywhere in the world as long as there is an Internet connection. The Play framework has been designed to embrace the characteristics of modern web applications such as handling long-running requests and manipulating data streams.
This book shows you how to write such web applications using Play. I designed it to be progressive so that you can quickly write a running application and then enhance it to benefit from all the components of the Play stack, or from lower-level APIs if you need more control.
Code examples are given in both Scala 2.10 and Java 8 (except for some APIs that have no Java counterpart). You can find executable applications based on the code examples of the book at http://github.com/julienrf/pfe-samples.
Finally, I encourage you to browse the API documentation of the framework to complete the content of this book. You can find it online at http://www.playframework.com/documentation.
Chapter 1, Building a Web Service, explains how to turn an application into a web service by exposing its resources and features as HTTP endpoints.
Chapter 2, Persisting Data and Testing, shows how you can integrate a persistence system to your Play application and how to write specifications of your HTTP layer.
Chapter 3, Turning a Web Service into a Web Application, goes one step further by showing you how the Play framework can help you to define HTML pages for your application and handle HTML forms.
Chapter 4, Integrating with Client-side Technologies, gives you insights on ways to manage the production of web assets from the build system of your Play application.
Chapter 5, Reactively Handling Long-running Requests, dives deeper in the framework internals and explains how to leverage its reactive programming model to manipulate data streams.
Chapter 6, Leveraging the Play Stack – Security, Internationalization, Cache, and the HTTP Client, presents additional components that are part of the Play stack.
Chapter 7, Scaling Your Codebase and Deploying Your Application, looks back at the code of your application and provides patterns to keep it modular and easy to maintain. It also explains how to deploy your application in a production environment.
The content of this book is based on Play 2.3.x and shows both Scala and Java APIs. Though this book uses Java 8, Play supports Java 6, so all you need to start developing a Play application is at least JDK 6. Chapter 1, Building a Web Service, explains how to install activator, a command-line tool to generate starter application skeletons and then manage their life cycle (running, testing, and so on). Finally, you also need a web browser to use your applications.
This book targets Java or Scala developers who already have some knowledge of web development.
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: "Source files are under the app/ directory."
A block of code is set as follows:
val index = Action {
Ok("Just Play Scala")
}When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:
val index = Action {
Ok("Just Play Scala")
}Any command-line input or output is written as follows:
$ curl -v http://localhost:9000/items
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: "If everything works fine, your browser should show a page titled Just Play Scala (or Just Play Java)."
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