When pharmaceutical companies develop drugs, they are targeting specific ailments or situations. Similarly, IT development platforms and frameworks target specific use cases. And the "sweet spot" for the ADF framework is data-handling applications.

What is a data-handling application? It is an application whose primary function is to gather data, process them, and display them back to the user as tables or graphs. Examples of data-handling applications are membership databases, project and task management, or accounting programs.

With very powerful declarative features, you can build most of your application without having to write any code, and the advanced user interface components make it easy to build an attractive user interface including interactive graphical displays of your data.

After release, some drugs are found to be potentially useful for other conditions than those for which they were developed and tested. This is called "off-label use" — using the drug for something that it was not intended for.

A similar situation occurs in the development of IT systems –– developers choose a tool that is a brilliant choice for one type of applications and try to use it for other types.

The classic case of "off-label use" of ADF is to build an application where you require absolute control over every pixel and every interaction. Such control is often possible to achieve with ADF, but it takes a big effort and requires deep modifications to the core of the framework.

In medicine, some people are allergic to certain medicines and should not be given them.

Similarly, there are some types of highly interactive applications like games or photo editing that are definitely unsuited for ADF.

ADF Essentials contains everything you need to build a data-handling application –– but of course, there has to be some additional features only available to enterprise customers with a full ADF license.

Some of the things not included in ADF Essentials include ADF Mobile, ADF Security (which is based on Oracle Platform Security Services, available only in WebLogic), Web Service Data Controls, ADF Desktop Integration, and so on. Refer to the ADF Essentials "Frequently Asked Questions" document for the full list.

However, it is worth repeating that everything you need in order to build data-handling applications is there. Actually, everything is there –– the restriction is only a legal and licensing issue.

Throughout this book, a sample application for a DVD rental shop is built. You can follow along in JDeveloper as you read, learning ADF hands-on.

The data model is the standard sakila database schema that comes with MySQL. The part we use consists of the customer, film, inventory, and rental tables –– their relationship looks as shown in the following diagram:

We will build three application screens: one simple screen for registering a rental, and two connected screens for searching for a customer and registering a return. These two screens look as shown in the following diagram:

Chapter 1, My First ADF Essentials Application, shows you how to install all the software and build a very simple application to prove that everything works.

Chapter 2, Creating Business Services, describes what Business Components are and how they are used in the example application. No code required!

Chapter 3, Creating Task Flows and Pages, shows you how to build ADF task flows that control the flow of your application and how to build the ADF pages where the user interacts with the data. Still no code required!

Chapter 4, Adding Business Logic, explains how to add business logic to your application –– this is where you'll have to write some actual Java code to implement functionality that ADF does not offer declaratively.

Chapter 5, Building Enterprise Applications, demonstrates how you go about building a larger application, using subsystems and ADF libraries to divide a big application into more manageable parts. We'll quickly build the whole DVD rental application again in this chapter using proper enterprise methodology.

Chapter 6, Debugging ADF Applications, shows you how to use ADF logging and debugging features to troubleshoot any problems you might experience during your ADF development.

Chapter 7, Securing an ADF Essentials Application, implements Apache Shiro to secure your application. Remember that there were some ADF-specific security features not part of ADF Essentials? This chapter shows you a fully-functional alternative.

Chapter 8, Build and Deploy, demonstrates how to use Apache Ant to create build scripts that compile, build, and deploy an entire enterprise application, including subsystems and ADF libraries.

This book uses the following software:

Chapter 1, My First ADF Essentials Application, explains where to get the software, how to install it, and how to configure all the parts to work together.

This book is for every web developer who wants to build data-handling applications quickly and efficiently. The book does not require any preconditions –– even beginners can use the powerful declarative features of ADF to build basic applications completely without programming.

Most real-life applications will of course require some programming to implement the business logic that is specific to your application. ADF uses Java to implement business logic, so a basic understanding of Java programming is required for most applications. A bit of knowledge about web applications in general will also be beneficial.

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: "Just like a SELECT statement can join data from multiple tables, a view object can join data from multiple entity objects".

A block of code is set as follows:

protected void doDML(int operation, TransactionEvent e) {
  super.doDML(operation, e);
}

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

if (operation == DML_INSERT) {
  String insStmt = "{call insertActor (?,?)}";
  cstmt = getDBTransaction().createCallableStatement(insStmt, 0); 
  try { cstmt.setString(1, getFirstName());
    cstmt.setString(2, getLastName());
    cstmt.execute();
  }
  catch (Exception ex) {
  ...
  }

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: "clicking on the Next button moves you to the next screen".

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