Play for Java shows you how to build Java-based web applications using the Play 2 framework. . For a Java developer, the Play web application framework is a breath of fresh air. . eBook $ pdf + ePub + kindle + liveBook about: Manning · tokens · MEAP · eBooks · liveVideo · liveBook · liveAudio · our covers. Fill Play For Java Pdf, download blank or editable online. Sign, fax and Результаты поиска: Play или for или Java или MEAP или v8 Play for Scala MEAP. Play Framework was created to revolutionize Java web application . the Manning Online Author forum after reviewing the Early Access (MEAP) chapters. .com/presentations/win-usa/bh-wingrossman/bh-wingrossman-up .pdf.
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Co-author of the book Play 2 with Scala in Action. 2 Play with Java and Scala .. Manning Early Access Program (MEAP) 'next month'. MEAP Edition. Manning Early Access Running Hadoop requires Java ( version is the minimum recommended; later versions are better). .. ecosystem, and some suggestions to how they can play a part in solving data management. Chapter 3 looks at how inter-process communication (IPC) plays much more critical role in a . consisting of a single Java Web Application Archive (WAR) file. Well known sites such as site [PDF], trekouthemsogold.cf, Groupon, and Gilt have all.
Nevertheless, FP is a truly radical shift in how programs are organized at every level—from the simplest of loops to high-level program architecture. The style that emerges is quite different, but it is a beautiful and cohesive approach to programming that we hope you come to appreciate. In this book, you will learn the concepts and principles of FP as they apply to every level of programming.
We begin in this chapter by explaining what a pure function is, as well as what it isn't. We also try to give you an idea of just why purity results in greater modularity and code reuse.
Furthermore, if it really is a function, it will do nothing else. In other words, a function has no observable effect on the execution of the program other than to compute a result given its inputs; we say that it has no side effects. We sometimes qualify such functions as pure functions to make this more explicit. You already know about pure functions.
It takes two integer values and returns an integer value. For any two given integer values it will always return the same integer value. Another example is the length function of a String in Java, Scala, and many other languages. For any given string, the same length is always returned and nothing else occurs.
We can formalize this idea of pure functions by using the concept of referential transparency RT. This is a property of expressions in general and not just 7 functions. For the purposes of our discussion, consider an expression to be any part of a program that can be evaluated to a result, i.
This has no side effect. The evaluation of this expression results in the same value 5 every time.
This is all it means for an expression to be referentially transparent—in any program, the expression can be replaced by its result without changing the meaning of the program. And we say that a function is pure if its body is RT, assuming RT inputs. SIDEBAR Referential transparency and purity An expression e is referentially transparent if for all programs p, all occurrences of e in p can be replaced by the result of evaluating e, without affecting the observable behavior of p.
A function f is pure if the expression f x is referentially transparent for all referentially transparent x. See the chapter notes for more discussion. When expressions are referentially transparent, we can imagine that computation proceeds very much like we would solve an algebraic equation.
We fully expand every part of an expression, replacing all variables with their referents, and then reduce it to its simplest form. At each step we replace a term with an equivalent one; we say that computation proceeds by substituting equals for equals. In other words, RT enables equational reasoning about programs. This style of reasoning is extremely natural; you use it all the time when understanding programs, even in supposedly "non-functional" languages.
Let's look at two examples—one where all expressions are RT and can be reasoned about using the substitution model, and one where some expressions violate RT. There is nothing complicated here, part of our goal is to illustrate that we are just formalizing something you already likely understand on some level.
If you wish to "modify" a string, you must create a copy of it.
The values of r1 and r2 are the same as before, so x was referentially transparent. What's more, r1 and r2 are referentially transparent as well, so if they appeared in some other part of a larger program, they could in turn be replaced with their values throughout and it would have no effect on the program.
Now let's look at a function that is not referentially transparent. Consider the append function on the scala. StringBuilder class. This function operates on the StringBuilder in place. The previous state of the StringBuilder is destroyed after a call to append. Let's now see how this side effect breaks RT. We therefore conclude that StringBuilder. What's going on here is that while r1 and r2 look like they are the same expression, they are in fact referencing two different values of the same StringBuilder.
By the time r2 calls x. If this seems difficult to think about, that's because it is. Side effects make reasoning about program behavior more difficult. Conversely, the substitution model is simple to reason about since effects of evaluation are purely local they affect only the expression being evaluated and we need not mentally simulate sequences of state updates to understand a block of code.
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Campbell Ritchie. Congratulations, all four of you. Liutauras Vilda. For a Java developer, the Play web application framework is a breath of fresh air.
With Play you get the power of Scala's strong type system and functional programming model, and a rock-solid Java API that makes it a snap to create stateless, event-driven, browser-based applications ready to deploy against your existing infrastructure. Play for Java teaches you to build Java-based web applications using Play 2. This book starts with an overview example and then explores each facet of a typical application by discussing simple snippets as they are added to a larger example.
Along the way, you'll contrast Play and JEE patterns and learn how a stateless web application can fit seamlessly in an enterprise Java environment. You'll also learn how to develop asynchronous and reactive web applications.
Nicolas Leroux is a core developer of the Play framework. Sietse de Kaper develops and deploys Java-based Play applications. Play for Java. Helps you transition to more productive ways to build modern web apps.
Table of Contents takes you straight to the book detailed table of contents. Chapter 1 An introduction to Play 1. What Play is. High-productivity web development. Chapter 2 The parts of an application 2.
Introducing our application. A rundown of a Play application. Adding a controller and actions. Mapping URLs to action methods using routes.
Adding a model and implementing functionality. Chapter 4 An enterprise app, Play-style 4. Recalling what an enterprise application is. Defining our warehouse enterprise application.
Controllers and action methods. Returning results from action methods.