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From jayachandra <jayachan...@gmail.com>
Subject Re: [Axis2] Need for children API for OMDocument
Date Wed, 01 Jun 2005 13:32:02 GMT
While duplicating the child API into OMDocument I got stuck at something.
The addChild() method of in turn tries to setParent(), and the
datamember parent is rigidly typed to be an OMElement only.
     /**
     * Field parent
     */
    protected OMElementImpl parent;

Now that OMDocument can also be a parent other than just OMElement, my
suggestion would be to have a wrapper interface OMParent that contains
in it the child API methods ( 6 of them). Its good to have child
navigation API within OMParent than anywhere else (currently it's in
OMElement). Subsequently OMElementImpl class and OMDocument class if
they implement this OMParent all the existing code will remain to be
intact with the additional desired functionality that OMDocument can
hold multiple entities in it.

Thanks
Jaya

My idea boils down to something like 

//child navigation API methods will be shifted from OMElement to
OMParent interface
public interface OMParent {
  public void addChild(OMNode omNode);
  public Iterator getChildrenWithName(QName elementQName) throws OMException;
  public OMElement getFirstChildWithName(QName elementQName) throws OMException;
  public Iterator getChildren();
  public void setFirstChild(OMNode node);
  public OMNode getFirstChild();
}

//OMElementImpl should implement OMParent
public class OMElementImpl extends OMNodeImpl implements OMParent,...{...}

//OMDocument should implement OMParent
public class OMDocument implements OMParent {...}

//The parent datamember in OMNodeImpl will be typed as OMParent type
public class OMNodeImpl implements OMNode {
...
protected OMParent parent;  // << parent should no longer be OMElementImpl type
...
...
}

Thank you
Jayachandra

On 6/1/05, jayachandra <jayachandra@gmail.com> wrote:
> Yeah! that's a wise way rather than extending OMElement. Apart being
> more clear on the readability front it also reduces unnecessary
> placeholders from creeping into OMDocument.
> 
> Jaya
> 
> On 6/1/05, Aleksander Slominski <aslom@cs.indiana.edu> wrote:
> > jayachandra wrote:
> >
> > >Can someone respond on this, plz.
> > >
> > >
> > why not model it exactly as it is in XML Infoset - so have children API
> > but do not extend OMElement just duplicate it (AFAICT Document is not
> > Element ...)
> > http://www.w3.org/TR/xml-infoset/#infoitem.document
> >
> > alek
> >
> > >Thanks
> > >Jaya
> > >
> > >On 5/31/05, jayachandra <jayachandra@gmail.com> wrote:
> > >
> > >
> > >>Hi devs,
> > >>
> > >>I have two suggestions regarding OMDocument
> > >>
> > >>First - a trivial one:
> > >>---------------------------
> > >>It lacks an interface definition in the package org.apache.axis.om and
> > >>a direct implementation class with name OMDocument.java is coded in
> > >>the o.a.a.om.impl.llom package. In line with how rest of the code is
> > >>arranged, I suggest we have in o.a.a.om package an interface with name
> > >>OMDocument.java listing out the setter and getter methods for
> > >>rootElement. And in the OMFactory interface we will add an extra
> > >>signature something like createOMDocument so as to enable other than
> > >>llom factory to be able to provide OMDocument implementation. Let the
> > >>implementation class in impl.llom package be named as
> > >>OMDocumentImpl.java
> > >>
> > >>Second - this is a critical design issue:
> > >>--------------------------------------------------------
> > >>Looking at the current OMDocument support I've realized that it
> > >>doesn't have a child navigation API. We might be doing away without it
> > >>as far as soap processing is considered. But without the child
> > >>navigation API in it, XMLInfoset can never be fully supported because
> > >>in an XML document other than the unique root element, at the same
> > >>level we can have several other nodes like documentation comments,
> > >>processing instructions, DTD element etc.
> > >>Enabling child API in OMDocument, implementation wise is not any
> > >>difficult. It can be just making it extend OMElement. Something like
> > >>public interface OMDocument extends OMElement ;
> > >>
> > >>Semantically if the above looks confusing and weird (OMDocument being
> > >>an OMElement !!??!!), alternatively we can copy paste the already
> > >>coded child API functionality of OMElementImpl into OMDocumentImpl
> > >>letting OMDocument to stand on its own without extending any other
> > >>interface. Also, performance wise these changes are not going to add
> > >>any significant overhead.
> > >>
> > >>Anticipating thoughts, ideas, suggestions
> > >>
> > >>Regards
> > >>Jaya
> > >>
> > >>
> > >>
> > >
> > >
> > >
> > >
> >
> >
> > --
> > The best way to predict the future is to invent it - Alan Kay
> >
> >
> 
> 
> --
> -- Jaya
> 


-- 
-- Jaya

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