Agenda

• Brief History
• Technical Overview
• Whiz-Bang Demo
• API Details
• Implications
• Yet Another Demo

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Service UI Participants

Ken Arnold Michel Burger Jeffrey Carpenter Alvin Chin James Cotsios Bill Day Cees de Groot Haruo Fukuda Keith Goethert Brian Jeltima Bruce Jackson Dave Judd Alan Kaminsky James Kempf

Peter Korn Adam Levin-Delson Gregory M. Lewis Sing Li Michael Los John McClain Bruno Melloni Mike Morris Uttam Narsu Jan Newmarch Wiven Nettles Olufisayo Omojokun Hugo Jose Pinto Sung Lu Ruo

Harry Saddler Jason Sando Michael Sargent Bob Scheifler Jerome Scheuring Maurice Schoenmakers James Staten Keith B. Thompson Jimmy Torres Bill Venners Jim Waldo Willie Walker Greg Wonderly Phong Yau

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Bundles of Functionality

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Client UI

• Supplied by client programmer
• Limited by programmer's prior knowledge

  package net.jini.blender;
  
  public interface Blender {
  
      void blend();
  }
  

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Service UI

• Can give access to full functionality
• Can be branded
• Increases accessibility to users

  package com.artima.contrived.examples;
  import net.jini.blender.Blender;
  
  public class GroovyBlender
      implements Blender {
  
      public void blend() {}
      public void frappe() {}
      public void puree() {}
      public void chop() {}
  }
  

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The ServiceUI Project

• To use a service UI, clients need prior knowledge
• We needed a standard way to:
  • Associate UIs with services
  • Access those UIs at the client

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User Adapters

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UI Descriptors

• UI provider describes UIs
• Client decides

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Class UIDescriptor

package net.jini.lookup.entry;

// imports...

public class UIDescriptor extends AbstractEntry {

    public String role;
    public String toolkit;
    public Set attributes;
    public MarshalledObject factory;

    //...
}

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UI Role

• Describe purpose of UI
• Examples: main, admin, about
• UIDescriptor.role = fully qualified name of role interface

package net.jini.lookup.ui;

public interface MainUI {

    String ROLE = "net.jini.lookup.ui.MainUI";
}

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The Role Interface

• UI object implements the role interface
• MainUI, AdminUI, and AboutUI are tag interfaces
• Role interfaces can declare methods

package com.artima.calcserv;
import net.jini.lookup.ui.MainUI;

public class CalcJFrame extends JFrame
    implements MainUI {

    //...
}

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UI Attributes

• UIDescriptor.attributes = a set of objects that describe the UI
• Four attribute classes defined:
  • AccessibleUI
  • Locales
  • RequiredPackages
  • UIFactoryTypes

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AccessibleUI Attribute

• Says two things about the UI:
  • Implements javax.accessibility.Accessible
  • Programmer did the necessary work

package net.jini.lookup.ui.attribute;

public class AccessibleUI
    implements java.io.Serializable {

    public boolean equals(Object o) {}
    public int hashCode() {}
}

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Locales Attribute

• Describes supported locales

package net.jini.lookup.ui.attribute;
import java.util.*;

public class Locales
    implements java.io.Serializable {

    public boolean isLocaleSupported(Locale locale) {}
    public Locale getFirstSupportedLocale(
        List locales) {}
    public Iterator iterator() {}
    public Set getLocales() {}
    //...
}

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RequiredPackages Attribute

• Lists packages required by the UI:
  • fully qualified package name
  • package version number

package net.jini.lookup.ui.attribute;

import java.util.*;

public class RequiredPackages
    implements java.io.Serializable {

    public Iterator iterator() {}
    public String getVersion(String packageName) {}
    public Map getRequiredPackages() {}
}

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UI Factories

• Don't want to serialize UI objects
• Instead, serialize a UI factory
• To get the UI, Client invokes factory method
• Factory methods declared in UI factory interfaces:
  • getJFrame() declared in interface JFrameFactory
  • getDialog() declared in DialogFactory

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UIFactoryTypes Attribute

• Lists UI factory interfaces implemented by the factory object
  • (Factory is stored in UIDescriptor.factory)

package net.jini.lookup.ui.attribute;

import java.util.*;

public class UIFactoryTypes
    implements java.io.Serializable {

    public boolean isAssignableTo(Class classObj) {}
    public Iterator iterator() {}
    public Set getTypeNames() {}
}

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UI Toolkit

• UIDescriptor.toolkit = package name of primary UI toolkit used by UI
  • "javax.swing"
  • "java.awt"
• Enables clients to narrow search for services based on UIs offered

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UI Factory Interfaces

• Family of interfaces, each with targeted factory methods:
• AWT
  • DialogFactory
  • FrameFactory
  • PanelFactory
  • WindowFactory
• Swing
  • JDialogFactory
  • JFrameFactory
  • JComponentFactory
  • JWindowFactory

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JFrameFactory

package net.jini.lookup.ui.factory;

import javax.swing.JFrame;

public interface JFrameFactory
    extends java.io.Serializable {

    String TOOLKIT = "javax.swing";
    String TYPE_NAME =
        "net.jini.lookup.ui.factory.JFrameFactory";

    JFrame getJFrame(Object roleObject);
}

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Separating Codebases

• Must not force clients to download JAR files for UI's they'll never use

public String role;
public String toolkit;
public Set attributes;
public MarshalledObject factory;

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Marshalling the UI Factory

UIDescriptor descrip = new UIDescriptor();

Class c = RMIClassLoader.loadClass(
    "http://minovia:8086/calcjframe.jar",
    "com.artima.calculator.ui.CalcJFrameFactory");

Object factory = c.newInstance();
descrip.factory = new MarshalledObject(factory);

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Unmarshalling the UI Factory

• Client can call getUIFactory() on UIDescriptor

public final Object getUIFactory(
    final ClassLoader parentLoader)
        throws IOException, ClassNotFoundException {}

• Must pass a class loader that can load the classes of the role object

Object uiFactory = selectedDescriptor.getUIFactory(
    serviceItem.service.getClass().getClassLoader());

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Generating the UI

• Client invokes a factory method, passing in the role object

JFrameFactory swingJFrameFactory = (JFrameFactory) uiFactory;

JFrame jf = swingJFrameFactory.getJFrame(serviceItem);

jf.setLocation(100, 100);
jf.setVisible(true);
//...

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UI Talks to the Service

public class CalcPanel extends Panel {

    private CalculatorService calcService;

    public CalcPanel(CalculatorService cs) {

        this.calcService = cs;

    //...

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Conclusion

• Can add new roles, factories, and attributes
• Services can be used by both people and software
• Can create different UIs for different client devices
• More natural UIs than web pages