EclipseLink/DesignDocs/384399

Design Specification: MOXy Footprint Reduction

ER 384399

Document History

Date	Author	Version Description & Notes
2012/07/05	Blaise Doughan	Work In Progress

Project overview

Problem

The install footprint is currently preventing MOXy from being bundled with other software and used on mobile platforms.

XML Binding Install Footprint (EclipseLink 2.4)

Bundle	Size
org.eclipse.persistence.moxy_2.4.0.v20120608-r11652.jar	455 KB
org.eclipse.persistence.asm_3.3.1.v201206041142.jar	271 KB
org.eclipse.persistence.core_2.4.0.v20120608-r11652.jar	4711 KB
	5437 KB

JSON Binding Install Footprint (EclipseLink 2.4)

Bundle	Size
org.eclipse.persistence.moxy_2.4.0.v20120608-r11652.jar	455 KB
org.eclipse.persistence.asm_3.3.1.v201206041142.jar	271 KB
org.eclipse.persistence.core_2.4.0.v20120608-r11652.jar	4711 KB
org.eclipse.persistence.antlr_3.2.0.v201206041011.jar	190 KB
	5627 KB

Goals

• Reduce the install footprint to 1 MB (from 5.4 MB)
• Be compatible with Project Jigsaw

Concepts

Package Splitting

This is when classes from the same package are distributed among different bundles. This is not compatible with OSGi, and therefore is something that we can not do.

Generics & Parameterized Types

This design makes use of generics, below is an example if you are not familiar with the mechanism in Java.

package demo;
 
import java.lang.reflect.Method;
 
public class Demo {
	private static String METHOD_NAME = "sample";
	private static Class<?>[] PARAMETER_TYPES = new Class[] {String.class};
 
	public static void main(String[] args) throws Exception {
		// Use Method - Test Method Can Be Called
		Integer a = new Foo().sample("A"); // YES
		Integer b = new Bar().sample("B"); // YES
		Integer c = new Baz().sample("C"); // YES
 
		// Reflection - Test Method Accessed Via Reflection
		hasMethod(Foo.class, METHOD_NAME, PARAMETER_TYPES); // YES
		hasMethod(Bar.class, METHOD_NAME, PARAMETER_TYPES); // NO
		hasMethod(Baz.class, METHOD_NAME, PARAMETER_TYPES); // YES
	}
 
	private static void hasMethod(Class<?> clazz, String methodName, Class<?>[] parameterTypes) {
		try {
			Method method = clazz.getMethod(methodName, parameterTypes);
			System.out.println(method);
		} catch(NoSuchMethodException e) {
			e.printStackTrace();
		}
	}
 
	// Regular Java Class
	static class Foo {
		public Integer sample(String string) {
			return null;
		}
	}
 
	// Parameterized Type
	static abstract class AbstractBar<RETURN, PARAMETER> {
		private RETURN value;
 
		public RETURN sample(PARAMETER parameter) {
			return value;
		}
	}	
 
	// Subclass of Parameterized type
	static class Bar extends AbstractBar<Integer, String>{
	}
 
	// Subclass of Parameterized type that overrides method from super class
	static class Baz extends AbstractBar<Integer, String> {
		@Override
		public Integer sample(String parameter) {
			return super.sample(parameter);
		}
	}
}

Project Jigsaw

Is a standard module system being designed for the Java SE platform. It is being applied to the JDK itself. While this feature is not dependent on Jigsaw, care will be taken as to what modules we will need to depend on.

• http://openjdk.java.net/projects/jigsaw/

Requirements

1. All bundles must remain binary compatible except the OXM aspects of org.eclipse.persistence.core.

Design Constraints

1. All bundles must remain binary compatible except the OXM aspects of org.eclipse.persistence.core.

Design / Functionality

Current (edit)

Proposed (edit)

Bundle Changes

New Bundle - org.eclipse.persistence.micro

This bundle will include the all the common classes to both MOXy and JPA.

Modify Bundles - org.eclipse.persistence.moxy & org.eclipse.persistence.core

The OXM classes from core will be moved to MOXy.

GUI

N/A

Config files

N/A

Documentation

The following items will need to be documented:

• What the binary incompatibilities are (if any).
• How to migrate to the new release.

Open Issues

This section lists the open issues that are still pending that must be decided prior to fully implementing this project's requirements.

Issue #	Owner	Description / Notes
1	Peter/Doug	Does the implementation of this feature require us to bump the version number to 3.0?

Decisions

This section lists decisions made. These are intended to document the resolution of open issues or constraints added to the project that are important.

Issue #	Description / Notes	Decision

Future Considerations

During the research for this project the following items were identified as out of scope but are captured here as potential future enhancements. If agreed upon during the review process these should be logged in the bug system.