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Arooa Exposed

Introduction

In this section we'll look at the Arooa Framework without Oddjob. Arooa was written for the requirements of Oddjob and not to be yet another Java Bean framework. These are the reasons for writing Arooa over using an existing framework:

Cut And Paste:
Arooa allows a bean configuration to be cut out of one file and pasted into another while Beans are active. The source and destination Beans are dynamically reconfigured in the process.
Runtime Configuration
Arooa can re-evaluate and re-inject properties into a Bean at any time.
Advanced Type Conversion:
Properties are exchanged between beans, not just set from text configuration. Arooa try's to find a conversion path between any both types whatever they might be.
GUI Bean Configuration:
Arooa provides a Swing Component to change A Beans configuration.

If you share these requirements and want to use Arooa in your own code thenn read on. If you don't then read on anyway - you might find it interesting.

Parsers

An ArooaParser is the starting point for most things Arooa. An ArooaParser parses an ArooaConfiguration

When an ArooaParser parses an ArooaConfiguration it generally creates something. That something is typically some Java Beans, but might be a GUI form, or some XML.

An ArooaConfiguration is generally something that can be parsed. That something is typically some XML but it might be a GUI form, or some Java Beans.

So we can go from XML to Beans to Forms to Beans to XML, and this is pretty much what we do.

The three main ArooaParsers of interest are StandardArooaParser for Beans, DesignParser for Forms, and XMLArooaParser for XML.

There's only one main ArooaConfiguration which is XMLConfiguration. For Beans and Forms the ArooaConfiguration is captured in their contexts. What's their contexts? It's their ArooaContext but more on them later.

Let's take a closer look at our three somethings.

Beans

Most of the time Arooa configures a single Bean, because you know what you want to configure. The StandardArooaParser takes a root Object and applies the configuration to it. A StandardFragmentParser can be used instead which will create the object if that's what you require. It's use is very similar to what will be described here.

Let's start with the ThirdComponent we couldn't configure in the previous section.

Here's the configuration for just our component:

<anything>
    <person>
        <bean class="org.oddjob.devguide.Person" title="Mr" firstname="John" surname="Smith"/>
    </person>
</anything>

Note that the document element can be anything, as it's not used for Object creation. Here's the code that will configure a our ThirdComponent: 

package org.oddjob.devguide;

import java.io.File;

import org.oddjob.arooa.ArooaParseException;
import org.oddjob.arooa.ArooaSession;
import org.oddjob.arooa.standard.StandardArooaParser;
import org.oddjob.arooa.xml.XMLConfiguration;

public class StandardAPExample {

    public static void main(String... args) throws ArooaParseException {
    
        if (args.length != 1) {
            System.err.println("Usage: file-name");
            System.exit(-1);
        }
        
        XMLConfiguration configuration = 
            new XMLConfiguration(new File(args[0]));
        
        ThirdComponent component = new ThirdComponent();
        
        StandardArooaParser parser = new StandardArooaParser(component);
        
        parser.parse(configuration);
        
        ArooaSession session = parser.getSession();
        
        session.getComponentPool().configure(component);
    }
    
}

The StandardArooaParser treats our root Object as a component. Because of this we can configure it using the line session.getComponentPool().configure(component); Attempting to independently configure the components person would not be possible. session.getComponentPool().configure(component.getPerson()); would throw an Exception.

When we run it we get: 

Person Set.

Now there's loads I need to explain.

But I'm just not going to get round to it just now. I'm sorry. Maybe next time.

Forms

Lets take a quick look at how to create a form.

package org.oddjob.devguide;

import java.awt.Component;
import java.io.File;

import javax.swing.JFrame;
import javax.swing.WindowConstants;

import org.oddjob.arooa.ArooaParseException;
import org.oddjob.arooa.design.DesignFactory;
import org.oddjob.arooa.design.DesignInstance;
import org.oddjob.arooa.design.DesignParser;
import org.oddjob.arooa.design.GenericInstanceFactory;
import org.oddjob.arooa.design.view.SwingFormFactory;
import org.oddjob.arooa.parsing.ArooaContext;
import org.oddjob.arooa.parsing.ArooaElement;
import org.oddjob.arooa.xml.XMLConfiguration;

public class DesignParserExample {

	public static void main(String[] args) throws ArooaParseException {
	
		XMLConfiguration configuration = 
			new XMLConfiguration(new File("examples/devguide/exposed1.xml"));
		
		DesignParser parser = new DesignParser(
				new DesignFactory() {
					public DesignInstance createDesign(boolean component,
							ArooaElement element, ArooaContext parentContext) {
						return new GenericInstanceFactory().buildDesign(
								component, 
								element, 
								ThirdComponent.class.getName(), 
								parentContext);
					}
				});
		parser.setComponent(true);
		
		parser.parse(configuration);
		
		DesignInstance design = parser.getDesign();
		Component view = SwingFormFactory.create(design.detail()).dialog();
		
		JFrame frame = new JFrame();
		frame.getContentPane().add(view);
		frame.pack();
		frame.setVisible(true);

		frame.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
	}	
}

Run it and we get a very simple form:

Simple Form

The id property is added because we told the parser our design is for a component.

XML

Here's how to use XMLArooaParser to go from XML back to XML. 

package org.oddjob.devguide;

import java.io.File;

import org.oddjob.arooa.ArooaParseException;
import org.oddjob.arooa.xml.XMLArooaParser;
import org.oddjob.arooa.xml.XMLConfiguration;

public class XMLParserExample {

	public static void main(String[] args) throws ArooaParseException {
	
		XMLConfiguration configuration = 
			new XMLConfiguration(new File("examples/devguide/exposed1.xml"));
		
		XMLArooaParser parser = new XMLArooaParser();
		
		parser.parse(configuration);
		
		System.out.println(parser.getXml());
	}
}

Any when we run it:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<anything>
    <person>
        <class class="org.oddjob.devguide.Person" firstname="John" surname="Smith" title="Mr"/>
    </person>
</anything>
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