Re: [bdbxml] XMLInputStreams and regular InputStreams and w3c DOM objects.

John,

This is great for "pulling" contents of the db.

DB --> XMLDocument --> InputStream --> JAXP Source

Will it work for writing? Seems BDBXML uses a "pull" strategy for 
writing to the DB as well this is somewhat different than JAXP where 
transform results are "pushed" to an output stream.

JAXP Transformer --> JAXP Result --> OutputStream --> XMLDocument --> DB

In JAXP, "StreamResult" can take a Writer or an OutputStream as a target 
for writing XSLT output to. Is there an analog to this in the DB? For 
instance XMLOutputStream which one could push transform results into the 
DB with?


Finally an example of this usage would be in the XQuery API,

XMLResult is the product of an XQuery executed against the DB. I can see 
the need for multiple result formats for XMLResults as well, for this I 
do see that I can get back an XMLDocument as opposed to an XMLValue DOM:

XMLResult.next(XmlDocument document)

For instance, I may want to stream XMLResults directly to an 
OutputStream without retaining the XMLValues in memory (System.out or 
ServletResponse.getWriter())

...
XMLResult result = ...;
XMLDocument doc = null;
result.next(doc);

Question: When completing an XMLQuery against the DB, are the results in 
memory (as XMLValues) at execution or are they completed as I iterate 
over the XMLResult? The question is more specifically, If I can do 
something like "result.next(doc);" is the XMLDocument just backed by the 
in-memory XMLValue DOM or is it backed directly by the Database?

Either way I can use a JAXP identity transform to push the document to 
an OutputStream

Transformer trans = TransformerFactory.newFactory().newTransformer();

trans.transform(
    new StreamSource(doc.getContentAsXmlInputStream()),
    new StreamResult(System.out)
);

-Mark Diggory

John Snelson wrote:
> Moe wrote:
> 
>> OK, and how am I supposed to use:
>>
>> public XmlInputStream createURLInputStream(String baseId,
>>                                            String systemId,
>>                                            String publicId)
>>
>> What are baseId, systemId and publicId standing for? Are there any usage
>> examples online?
> 
> 
> mgr.createURLInputStream("", "file:...", "");
> 
> The good news is that I spent a day working on the Java version of 
> XmlInputStream, and I have now made it so that it can be properly 
> derived from. I have also implemented a constructor function for an 
> XmlInputStream that takes a java.io.InputStream - so you will be able to 
> use your favourite java stream instead. This will be available in the 
> 2.2 release of DB XML - which should be out pretty soon.
> 
> John
> 


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