Re: writing collection of refobjects through xmiwriter

Hi Martin and Ronald,

Martin Matula wrote:
 > Hi Ronald,
 > Now the problem is, how to enforce that
 > XMIReferenceProvider returns href (not xmi.id) in case when XMIWriter
 > is asking for href of object not contained in the collection that was
 > sent as a parameter. If the XMIReferenceProvider would return xmi.id
 > instead of href, XMIWriter would serialize that object (although it
 > was neither in the original collection nor it is a component of any
 > object in the original collection) and all the comonents of that
 > object transitively,
 > etc.
 > Do you think that this behavior is OK or would it be better to throw
 > an exception from the XMIWriter if xmi.id is returned where href was
 > expected?
 > Martin

Currently you are proposing that XMIReferenceProvider choose which
reference to give the XMIWriter. I propose that XMIReferenceProvider
should be able to give both form of references, and that the XMIWriter
will ask for whichever one it prefers:

      public interface XMIReference {
              /*  If a.getDocumentURI().equals(b.getDocumentURI()) then
               *  "a" and "b" are in the same file and so it _may_
               * choose Otherwise, it will _always_ choose getHref().
               */
          public String getDocumentURI();
              /*  always returns href form; never returns null. The
               *  location is relative to the document URI.
               *  XMIWriter would create the link using:
               */ xmiref.getDocumentURI() + xmiref.getLocation();
          public String getLocation();
              /*  always returns xmi.id form; never returns null. The
               *  XmiWriter can use (a) while writing links to the
               *  object, and possible (b) while generating the
               *  xmi.id attribute while writing the object itself???
               */
          public String getXmiId();
      }

Sample untested implementation:
      class SimpleXMIReference implements XMIReference {
           SimpleXMIReference(String document, String xmiId) {
                 this.document = document;
                 this.xmiId = xmiId;
           }
           public String getDocumentURI() { return document; }
           public String getXmiId()       { return xmiId;    }
           public String getLocation()    { return "#" + xmiId; }
           private String document, xmiId;
      }

In this case, XMIWriter.write(Collection, XMIReferenceProvidier) should
have enough information to do what was asked, because XMIWritier would
look something like this:

   writeLink(RefObject source, RefObject dest, XMIReferenceProvider p) {
      XMIReference destRef = p.getXMIReference(dest);
      if (p.getXMIReference(source).getDocumentURI()
                                   .equals(destRef.getDocumentURI())) {
          writeXmiIdRef(dest, destRef.getXmiId());
      } else {
        writeHref(dest, destRef.getDocumentURI(), destRef.getLocation());
      }
   }

- Brian