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RE: DB implementation - Relationships between Collection, Resource and XMLContainer

I got a response on the XML:DB list confirming the idea that Resources
should be contained in Collections so I moved on using the (to me) simplest
interpretation of that idea which is to have a Map in CollectionImpl that
has id as their key and the Resource object as the value. For the
XMLResourceImpl i chose to use a Node as the content for the Resource. I'm
now able to test all use cases for DOM successfully and are moving on to
the String based stuff now.

I'm not sure if choosing Node for Resource content is right. it works but
maybe I'm not considering all scenarios. When Lars put the skeleton code in
CVS he seemed to have had the idea to use an XMLContainer for the content
instead of Node. The difference would basically be:

1. Use aggregation. The Collection is stored in Ozone and it contains
XMLResources which contains Node objects. I changed the constructor to work
with this idea i.e.
    public XMLResourceImpl( String id, OzoneInterface database, Collection
collection) {

        this.database = database;
        this.collection = collection;
        this.id = id;

    }

2. Use association. Both Collections and the XML as XMLContainers are
explicitly stored in Ozone. The Collection would not have a Map but instead
a list of id's that allows for the XML document to be found using
objectForName(id). For this to be smooth a getName() method should be added
to XMLContainer so that id does not have to be specified twice in the
construction of the XMLRersourceImpl. i.e.

	public XMLResourceImpl( OzoneInterface database, Collection collection,
      	XMLContainer container ) {
          this.database = database;
          this.container = container;
          this.collection = collection;
          this.id = container.getName();

    }

Any ideas/suggestions?

Best regards,
Per

> -----Original Message-----
> From: ozone-dev-owner@ozone-db.org
> [mailto:ozone-dev-owner@ozone-db.org]On Behalf Of Per Nyfelt
> Sent: den 30 maj 2001 10:52
> To: ozone-dev@ozone-db.org
> Subject: XML:DB implementation - Relationships between Collection,
> Resource and XMLContainer
>
>
> I'm struggling with CollectionImpl.createResource(). What should be the
> relationships between org.xmldb.api.base.Collection,
> org.xmldb.api.base.Resource and org.ozoneDB.xml.util.XMLContainer? I
> something like the following in mind but I'm not sure this is a
> valid route:
>
>  public Resource createResource( String id, String type ) throws
> XMLDBException {
>         try {
>             if ( ( id == null ) || ( id.equals("") ) ) {
>                 id = createId();
>             }
>             if ( type.equals(XMLResource.RESOURCE_TYPE) ) {
> 		    // what to do with this?
>                 return new XMLResourceImpl(database,this,
> XMLContainer.newContainer( database, id));
>             }
>             else if ( type.equals(BinaryResource.RESOURCE_TYPE) ) {
>                 throw new XMLDBException( ErrorCodes.VENDOR_ERROR,
> "BinaryResource: Not yet implemented");
>             }
>             else {
>                 throw new
> XMLDBException(ErrorCodes.UNKNOWN_RESOURCE_TYPE);
>             }
>         }
>         catch (Exception e) {
>             throw new XMLDBException(ErrorCodes.UNKNOWN_ERROR,
> e.toString());
>         }
>     }
>
> Then for CollectionImpl.storeResource() i'm not sure how the storage of a
> Resource should be viewed. If Collection should aggregate Resources we
> should store the resource inside the Collection but then
> Collection needs to
> have a list (Map) of Resources. On the other hand if we store it as a
> separate object what denoted its relationship with a Collection?
>
>    public void storeResource( Resource res ) throws XMLDBException {
>         try {
>             String id = res.getId();
>             if ((id == null) || (id.length() == 0)) {
>                 id = createId();
>             }
> 		// what to do whith this?
>             database.createObject( Resource.class.getName(),
> OzoneInterface.Public, id);
>           }
>           catch (Exception e) {
>              throw new XMLDBException(ErrorCodes.UNKNOWN_ERROR,
> e.toString());
>           }
>     }
>
> Any suggestions?
>
> Best regards,
> Per
>
>