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Re: How to store/retrieve XML Documents in Ozone?

Wed, 27 Oct 1999 Ann Tecklenburg wrote:
>I see that we now have the XML DOM classes
>in the source tree, but I am not sure as how to best use
>them.

There are two ways to use PDOM in ozone:

1. Directly use an XML-Parser to create OzoneObjects (Elements, etc)
   For this you have to modify the XML-Parser to create OzoneObjects
   instead of their own DOM-Implementation. I used that with OpenXML,
   but there are a _lot_ of changes in the parser source, because there
   is no parser spec to change the DOM-Factory from OpenXML to the 
   ozone factory. So this is only for testing, but its more faster
   then the 2nd solution which is more elegant than the described.

2. The second way is to convert a given DOM to ozone-DOM. For this I
   wrote something like a DOM-Converter (org.ozoneDB.xml.util.DOMConvertUtil.java)
   The converter goes through the DOM-tree an creates an OzoneObject
   for each found DOM-node. You can use every W3C compliant DOM-Parser
   like XML4J or OpenXML. I added a small Parser interface to allow
   integration of other parsers as well..
   This is a small piece of code to demonstrate the DOM-Converter

<------------------->
            Parser              parser;
            DOMConverterUtil    converterUtil;
            Document            doc;
            RemoteDatabase      database = new RemoteDatabase();

            // create a parser of your choice
            parser = (Parser) Class.forName("org.ozoneDB.xml.util.IBMXMLParser").newInstance();
            // parser = (Parser) Class.forName("org.ozoneDB.xml.util.OpenXMLParser").newInstance();

            // open the connection on localhost at port 3333
            database.open ("localhost", 3333);

            // reload our database classes if we changed them
            database.reloadClasses();

            converterUtil = new DOMConverterUtil ();

            // open the real DOM converter (ozone object) through the helper class
            converterUtil.openConverter (database);

            // 
            doc = converterUtil.convertDOM (parser.parse (
                       new InputStreamReader (
                           new FileInputStream (
                               new File ("test.xml")))));

            // closing the converter means deleting the ozone converter object too
            converterUtil.closeConverter ();
<-------------------->
   
>Lets say I have a something that contains a valid XML Document and can be
>turned into an input stream, say a String, File, or whatever, how do I store
>and retrieve them to an OzoneDb?  If I create a Java class that contains a
>DTDDocument member, does Ozone automatically do the internal conversion or
>do I need to do the convert call directly?

Now you have a W3C-compliant Document (doc) which you can name to retrieve
it later time (database.nameObject ((..)doc, "myName") - attention, there is
a bug in nameObject()! - so this is just the theory :-))

To retrieve the stored document you have to use
database.objectForName("myName"); If you get an OzoneObject back, you can
go through the DOM-tree with W3C-DOM-API (getFirstChild(), getnextSibling()...)

At this time there is a bug in ozones PDOM implementation, the DOM-Converter
can´t convert XML nodes with attributes. But I will check this asap.

Regards,
Lars
--
________________________________________________________________ 
Lars Martin                          lars@softwarebuero.de
softwarebuero m&b (SMB)              http://www.softwarebuero.de