[jira] Updated: (TUSCANY-1527) Allow for custom data binding of DataObjects in a Swing UI

["Kris De Waele (JIRA)" <tu...@ws.apache.org>]

     [ https://issues.apache.org/jira/browse/TUSCANY-1527?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Kris De Waele updated TUSCANY-1527:
-----------------------------------

    Attachment: agfasdoui.tar.gz

the attachment agfasdoui.tar.gz contains the full source code of our custom ui binding extension.
No license granted to ASF, as this code is not intended for inclusion, since it depends on a proprietary UI framework.
This code is a basis for discussion and an example of what sort of things one could expect from a UI binding extension

Code will not compile as it has compile time dependencies on the proprietary ui framework which is not included

> Allow for custom data binding of DataObjects in a Swing UI
> ----------------------------------------------------------
>
>                 Key: TUSCANY-1527
>                 URL: https://issues.apache.org/jira/browse/TUSCANY-1527
>             Project: Tuscany
>          Issue Type: New Feature
>          Components: Java SDO Implementation
>            Reporter: bert.robben
>             Fix For: Java-SDO-Next
>
>         Attachments: agfasdoui.tar.gz, com.zip
>
>
> We're developing 3-tier applications with a swing client, JBoss app server and a couple of databases in the back-end. On the client side we use sdo objects as model objects for our UI. As such, we need a mechanism for binding our objects to the UI controls such that changes in the objects are reflected in the UI and vice versa.
> At the moment, there is no real standard for data binding and many different implementations exist. As such, it would not be a good idea to build support for this directly into the sdo core. Ideally, the sdo core would allow implementations supporting data binding to be added as extensions [an extension as in jar, module, bundle, component, ...]. This is a request for supporting this in Tuscany SDO.
> -----------------
> For our applications, we developed our own implementation of the sdo specification. This implementation is designed to support that kind of extensions. In the rest of this description, I'd like to show more details on our implementation to make this more clear and to serve as food for a possible discussion.
> Our sdo core module defines the abstract class AbstractPartialDataObject implementing DataObject. This class (together with its superclasses) implements the majority of the bevahiour of DataObject. This includes bi-directional property updates, type-safe properties, containment, ... It doesn't implement however the basic access to property values.
> Here's a code fragment.
> public abstract class AbstractPartialDataObject extends AbstractDataObject implements PartialDataObject {
> 	protected abstract Object basicGet(Property property);
> 	
> 	protected abstract void basicSet(Property property, Object value);
> 	
> 	public Object get(Property property) { ... }
>   public void set(Property property, Object value) { ... }
>    ...
> }
> The sdo core module also provides a non-abstract class DataObjectImplementation that provides a simple implementation of this abstract behaviour where the property values are stored in an ArrayList.
> On top of that we defined an extension that deals with our UI requirements. Our UI is based on a proprietary UI framework. This framework has the following requirements:
> - single valued properties should be exposed as XObservables. An XObservable is a kind of ValueModel that provides access to a value (get/set) and also allows for registration of change listeners
> - multi valued properties should be exposed as ListModel instances. A ListModel is a proprietary class (a bit similar to the javax.swing.ListModel) that provides List functionality and also allows for change listeners
> - the data object itself should allow registration of attribute change listeners that are notified each time a property changes   
> The extension implements these requirements by providing an appropriate subclass ObservableDataObject of AbstractPartialDataObject. The only other pieces of code needed in the extension is an appropriate implementation of DataFactory and a wrapper to deal with the differences between ListModel and List. 
> Here's the class with the most important code snippets.
> public class ObservableDataObject extends CompositePartialDataObject implements  {
>     private XObservable[] properties;
>     
>     protected ObservableDataObject(com.agfa.hap.sdo.Type type) {
>         super(type);
>         this.properties = new XObservable[type.getProperties().size()];
>         for (int i = 0; i < properties.length; i++) {
>             initializeProperty(type.getProperty(i));
>         }
>     }
> 	private XObservable<Object> initializeProperty(Property prop) {
> 		XObservable<Object> observable = XObservableFactory.create(prop.getType().getInstanceClass(), this);
> 		if (prop.isMany()) {
> 		    observable.init(new DataObjectListModel(this, prop));
> 		}
> 		properties[prop.getIndex()] = observable;
> 		return observable;
> 	}
>     public XObservable getObservable(commonj.sdo.Property property) {
>     	XObservable result = properties[property.getIndex()];
>         return result;
>     }
>     public ListModel getListModel(Property property) {
>     	return (ListModel) getObservable(property).get();
>     }
>     public ListModel getListModel(String property) {
>     	return (ListModel) getObservable(type.getProperty(property)).get();
>     }
>     @Override
>     public List getList(Property property) {
>     	return ((DataObjectListModel) getObservable(property).get()).asList();
>     }
>     
> 	@Override
> 	protected Object basicGet(Property property) {
>     	Object result = properties[property.getIndex()].get();
>     	if (property.isMany()) {
>     		result = ((DataObjectListModel) result).asList();
>     	}
>     	return result;
> 	}
> 	@Override
> 	protected void basicSet(Property property, Object value) {
> 			XObservable observable = properties[property.getIndex()];
> 			if (observable == UNINITIALIZED) {
> 				observable = initializeProperty(property);
> 			}
> 			observable.set(value);
> 	}
> 	
> 	
> }

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