Re: [xml-dev] Question for Xpath usage in setter, not query or transformation

[Burak Emir <Burak.Emir@epfl.ch>]

Chen, Andrew . wrote:

> Is it possible to set data in a DOM tree through a simple Xpath like 
> syntax?
>
(Although it is Java based, you might take some inspiration from this one)
At IBM research, people are working on a Java + XML, called XJ.

Here is a short summary of the WWW2004 conference poster. Vivek Sarkar 
presented it also at ECOOP2004 in Oslo.
http://www2004.org/proceedings/docs/2p340.pdf

Here's the extract of the code. They use backquotes `...` to embed XPath 
expressions in Java syntax.

 1 import "po.xsd";
 2 public class Discounter {
 3     public void giveDiscount(){
 4
          purchaseOrder po =
                 (purchaseOrder)XMLItem.load("po.xml", null);
 5
 6        XML<item> bulkPurchases =
                  po/item[quantity/text() > 50] ;
 7        for (int i = 0; i < bulkPurchases.size(); i++) {
 8
              item current = bulkPurchases.get(i);
 9
               `current/USPrice/text()` *= 0.80; // Deduct 20%
10        }
11        XMLItem.serialize(po, "po.xml");
12     }
13 }


Again, some fancy XML database API might also provide what you need but 
I do not know of any.
Berkeley DB XML by sleepycat and Apache do not seem offer such an update 
mechanism, but only "insert-before" and "insert-after".

Looks like something worth implementing, but if the programs are to be 
readable, it requires a clean and at the same time flexible XML API, 
something which does not seem to exist in the mainstream programming 
language world, or a language extension, which most users are not 
inclined to use.

cheers,
Burak