JavaFX for Business Applications

We have tested JavaFX technology and decided to provide you with a review of JavaFX as a foundation for RIA-based business application development, its positive and negative sides. The article also contains a description of most interesting and powerful features of JavaFX Script (a core language for JavaFX-based development) with short code examples.

References:   JavaFX Technology Hub   JavaFX Home   Chris Oliver's JavaFX weblog   InsideRIA online community

JAVAFX AS RIA PLATFORM FOR BUSINESS SOFTWARE

It includes a runtime and a tools suite that web scripters, designers, and developers can use to quickly build and deliver rich Internet applications for desktop, mobile devices, TV, and other platforms. At first glance JavaFX looks fine for development of media-oriented software (audio/video-enabled applications, games, etc.). But the traditional and main market for Java technologies is real business applications. So what is the place of JavaFX in the development of enterprise software? One possible answer to this question is found in a range of business applications that actively use data visualization, namely: JavaFX-based digital dashboards for Business Intelligence. JavaFX graphic features can be used to implement different kinds of interactive real-time updated charts and graphs (user changes reporting parameter and see the changes on a diagram immediately). JavaFX-based planning and scheduling software. JavaFX can be used to implement graphic-based interactive user interface for handling different types of time-tables and schedules. JavaFX-based online reporting. JavaFX can be used to display diagrams and charts online.

JAVAFX PERSPECTIVES

• JVM-base. JavaFX apps are running inside Java Virtual Machine. That means JavaFX shares all performance and security capabilities of Java runtime.
• W.O.R.A concept. Write One Run Anywhere concept that allows minimizing development costs and enlarging the potential marketplace. Sun positions JavaFX as a technology that would allow creating cross platform rich GUI internet applications. Potentially JavaFX applications will run on any desktop, browser, mobile device or any other device that runs the Java Runtime Environment.
• JavaFX Script. New language which is a mix of declarative statements for defining View layouts and procedural/imperative control statements. It allows splitting the development of static and dynamic part of UI. This should increase independency between designers and programmers and let the later to concentrate on business-logic and technical stuff while the first ones take care about look-and-feel.
• Easy access to Java. Makes JavaFX attractive to huge Java-developer community and greatly simplifies creating business and technical back-end for RIAs. It is also greatly simplifies extending existing Java-based enterprise business applications with a set of features typical for RIAs.

• Additional runtime environment is required. It makes JavaFX less user-friendly. Different RIA platforms require different runtime environments. This fact can become a nightmare for end-users. On the other hand interactive Web-applications built with pure Ajax/JavaScript capabilities don’t have such a limitation. If the user has a choice between an application that requires installing additional software and an application that requires only a browser I believe he selects the second one. However Ajax is not a panacea I think: It is less development-friendly and its capabilities are quite strict for rich application development.
• Lack of tools. Currently JavaFX provides so called JavaFX Productions Suite (a suite of tools and plug-in for creative tools that allows graphical assets to be exported to JavaFX applications) and NetBeans IDE 6.5 plug-in for JavaFX 1.0 (provides an integrated development environment for building, previewing, and debugging JavaFX applications). However their current capabilities are quite limited (e.g. JavaFX applications can be exported from Adobe Photoshop/Illustrator but can not be imported, NetBeans does not have visual layout-editor for JavaFX).
• Limited platform support. Despite the fact that JavaFX is positioned as a unified development and deployment platform for building RIAs across desktop, browser and mobile for now JavaFX 1.0 applications will run on any Windows or Mac OS X desktop running Java 1.5 or higher. Linux and Solaris platforms are not yet officially released as well. This greatly decreases the area of potential receivers. However it seems to be a temporary problem.
• Maturity. JavaFX relative maturity compared to the Silverlight and especially Flex is quite low. JavaFX is lacking some important common UI-components. For example there is no kind of data grid component. That would require developers to wrap Java JTable and program to it. So JavaFX developers should still have a background of a Java Swing programmer, which will be an obstacle for many Java developers. This also makes JavaFX less attractive to use for development of data-base front-end applications which is a typical case for business applications. The list of custom frameworks for JavaFX is also quite short for now. But keep in mind the fact that JavaFX is still 1.1 and the platform is being actively elaborated and extended.

JAVAFX SCRIPT. KEY FEATURES OVERVIEW

Declarative Syntax

JavaFX Script declarative syntax for constructing user interfaces contrasts with the more verbose series of method calls required to construct an equivalent interface in Java Swing directly.

import javafx.scene.Scene;
import javafx.scene.text.Font;
import javafx.scene.text.Text;
import javafx.stage.Stage;
 
Stage {
  title: " Hello, World!"
  width: 250
  height: 70
  scene: Scene {
          content: [
              Text {
                 content: "Hello, World!"
                 x:0
                 y:12
            }
          ]
  }
}


import javax.swing.JFrame;
import javax.swing.JLabel;
public class HelloWorld {
 
    public static void main(final String[] args) {
       JFrame frame = new JFrame("Hello, World!");
       frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
       frame.add(new JLabel("Hello, World!"));
       frame.pack();
       frame.setVisible(true);
    }
}

Data binding

package javafxbarchart;

import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.text.Text;
import javafx.scene.text.Font;
import javafx.scene.shape.Rectangle;
import javafx.scene.paint.Color;
import javafx.ext.swing.SwingSlider;
import javafx.geometry.Rectangle2D;

// Bar Cart Bottom position
def barBottom = 180;
//defining Swing Slider components to change projects' budget values
var project1Budget = SwingSlider { minimum: 0, maximum: 100000, value: 30000,
    vertical: false, impl_layoutX: 10, impl_layoutY: 13}
var project2Budget = SwingSlider { minimum: 0, maximum: 100000, value: 75000,
    vertical: false, impl_layoutX: 10, impl_layoutY: 45}
//binding bar heights to projects' budget values
var project1BarHeight = bind project1Budget.value / 1000;
var project2BarHeight = bind project2Budget.value / 1000;
//binding top Y position to bar height
var yPosProject1 = bind ( barBottom - project1BarHeight);
var yPosProject2 = bind ( barBottom - project2BarHeight);
//defining chart bar to display budget value for the first project
var chartBarProject1 = Rectangle { x: 40, width: 70,
                height: bind project1BarHeight,
                fill: Color.RED
                y: bind yPosProject1}
//defining chart label to display budget value for the first project
var project1BudgetLabel = Text { font: Font {size: 12},x: 50,
                //binding label caption to top Y bar position
                y: bind yPosProject1 - 5,
                //binding label caption to projectBudget value
                content: bind "{project1Budget.value} eur"}
... //similar definition for chart bar and label for the second project
Stage {
    title: "Project Budgets"
    width: 230
    height: 240
    scene: Scene {
        content: [
          //Sliders
          project1Budget, project2Budget,
          //Labels
          Text {font: Font {size: 12}, x: 70, y: 12,content: "Project 1 Budget"},
          Text {font: Font {size: 12}, x: 70, y: 45,content: "Project 2 Budget"},
          Text {font: Font {size: 12}, x: 40, y: barBottom + 10,
                content: "Project 1"},
          Text {font: Font {size: 12}, x: 110, y: barBottom + 10,
                content: "Project 2"}
          //Bar Chart
          chartBarProject1,
          project1BudgetLabel,
          chartBarProject2,
          project2BudgetLabel,
        ]
    }
}

Moreover, JavaFX script provides a triggering mechanism that allows binding custom behavior to variable value changes. JavaFX script introduces Replace Triggers that are arbitrary blocks of code that attach to variables and execute whenever the variable's value changes. According to the documentation, JavaFX triggers operate the same manner as SQL triggers.
Here is an example that shows the basic syntax: it defines a reportingYear variable and attaches a replace trigger to it. When the value of the reportingYear variable is being changed, the trigger prints out a message displaying its new value, validates that new value is greater then the minimal possible (2000) and sets it to the minimal value if validation is failed:

var reportingYear = 2008 on replace oldReportingYear {
println("\Changing reporting year from {oldReportingYear} to {reportingYear}");
  if (reportingYear < 2000){
    println("\Reporting year is less then minimal available. Setting reporting year to 2000...");
    reportingYear = 2000;
  }
};

Access to existing Java libraries

The following program demonstrates how to use Java capabilities at JavaFX script. It simply shows a User email address for the selected User.

package javaobjects;

import javafx.ext.swing.SwingComboBox;
import javafx.ext.swing.SwingComboBoxItem;
import javafx.scene.Scene;
import javafx.scene.text.Font;
import javafx.scene.text.Text;
import javafx.stage.Stage;
//importing Java libraries
import dataservices.User;
import dataservices.UserService;


var userEmail; //label content
/*binding variable to combobox selected item index in order automatically proccess
 selection changes */
var selectedUserNameIndex = bind userNameCombobox.selectedIndex on replace oldIndex {
    /*calling Java code. UserService is Java class.It can implement complex
     data acess logic (for example search in DataBase, remote call, etc.)*/
    def user = UserService.findUserByName(userNameCombobox.selectedItem.text);
    //calling method of Java object to evaluate new label content
    userEmail = user.getEmail()
}

//combobox for selecting a user name
var userNameCombobox = SwingComboBox {
    items: [
        SwingComboBoxItem{
        text:"User1"},
        SwingComboBoxItem{
        text:"User2"},
        SwingComboBoxItem{
        text:"User3"}
    ]
    selectedIndex: 0
    width: 100;

}
Stage {
    title: "Accessing Java Objects"
    width: 340
    height: 150
    scene: Scene {
        content: [
            Text {
                font: Font {
                    size: 12
                }
                x: 105
                y: 20
                //binding to variable for automatic update of label content
                content: bind "Email adress: {userEmail}" ;
            },
            userNameCombobox
        ]
    }
}


Usage of JavaFX objects in Java.

CustomJavaFXClass.fx
import java.lang.System;
public class CustomJavaFXClass {

    public attribute value: String;

    public function printValue(){
        System.out.println(value);
    }
}
  import javax.script.ScriptEngineManager;
import com.sun.javafx.api.JavaFXScriptEngine;

public class Main {

  public static void main (String[] args) {
    ScriptEngineManager manager =
        new ScriptEngineManager();

    JavaFXScriptEngine fxEngine =
        (JavaFXScriptEngine) manager.getEngineByName("javafx");

    try {

      String param = "JavaFX object created in Java";

      String script = String.format (
          "CustomJavaFXClass {value: \"%s\"}", param);

      Object fxObject = fxEngine.eval(script);

      fxEngine.invokeMethod(fxObject, "printValue");

    } catch (Exception ex) {
      ex.printStackTrace();
    }
  }
}        Interface
public interface IPrintableValue {
  public void printValue();
}

CustomJavaFXClass.fx
public class CustomJavaFXClass extends IPrintableValue

In Java program
String script = String.format ("CustomJavaFXClass {value: \"%s\"}", param);

IPrintable fxObject = (IPrintableValue) fxEngine.eval(script);
fxObject.printValue();

Integration with JavaScript

customApllet.Main.fx:
public function updateView():void {


  //updating application content
}

customPage.html:
<applet code=" customApllet.Main" width="600" height="300" id="appl" />
<script>
function updateView() {
var appl = document.getElementById("appl");
appl.script.updateView();
}
</script>

REFERENCES

1. JavaFX Technology Hub
2. JavaFX Home
3. Chris Oliver's JavaFX weblog
4. InsideRIA online community

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Posted by Elena Popretinskaya,   CTO