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From ymondrow <ymondrow...@randomhouse.com>
Subject Re: OMElement.declareDefaultNamespace() declares empty namespace for child element.
Date Sun, 11 Nov 2007 21:59:55 GMT

Thanks, I really appreciate it.  I'm also sitting on another bug, which
appears more serious than this one.  When a default namespace is declared on
a parent node, AXIOM repeats that default namespace declaration for each
child node, bloating the XML greatly.  I reported this in JIRA as
AXIS2-3155.  Here too, it's been already more than 2 months and it's not
been addressed.  This one is actually causing greater problems on our end,
so if you can take a look at that one too, I would really appreciate it.  I
am attaching the contents of AXIS2-3155 here.  Thanks a bunch! 

AXIOM writes out duplicate default namespace declarations 
--------------------------------------------------------- 

                 Key: AXIS2-3155 
                 URL: https://issues.apache.org/jira/browse/AXIS2-3155 
             Project: Axis 2.0 (Axis2) 
          Issue Type: Bug 
          Components: om 
    Affects Versions: 1.3 
         Environment: Microsoft Windows 2003 Server, Java 1.5.0_11.  Axis2
version 1.3 (uses AXIOM version 1.2.5). 
            Reporter: Yechiel Mondrowitz 
             Fix For: 1.3 


When there is a default namespace declaration in a parent node, it seems
that AXIOM repeats that default namespace declaration for every child node. 
So if this piece of XML, with a default namespace in the <outerTag> is fed
to AXIOM: 

<outerTag xmlns="http://someNamespace"> 
    <innerTag> 
        <node1>Hello</node1> 
        <node2>Hello</node2> 
   </innerTag> 
</outerTag> 

What AXIOM returns is this: 

<outerTag xmlns="http://someNamespace"> 
    <innerTag xmlns="http://someNamespace"> 
        <node1 xmlns="http://someNamespace">Hello</node1> 
        <node2 xmlns="http://someNamespace">Hello</node2> 
   </innerTag> 
</outerTag> 

While this may be valid XML, it doubles or triples the size of the XML. 
With large XML results, this can mean serious performance issues, as double
or triple the bandwith is needed to transport it across the wire.  This only
appears to happen when the OMElement has not yet been built in memory, but
is still in the stream.  After it is already built, the problem goes away. 
So this problem only occurs if toStringWithConsume(), or
serializeAndConsume() is called on the OMElement.  When toString() is called
however, the resulting XML is fine.  Here is a small program to illustrate: 


import org.apache.axiom.om.*; 
import org.apache.axiom.om.impl.llom.util.*; 

public class Test1 { 
    public static void main(String [] args) { 
        try { 
            String xmlString = 
                "<outerTag xmlns=\"http://someNamespace\">" + 
                    "<innerTag>" + 
                        "<node1>Hello</node1>" + 
                        "<node2>Hello</node2>" + 
                   "</innerTag>" + 
                "</outerTag>"; 

            OMElement elem = AXIOMUtil.stringToOM(xmlString); 
            System.out.println("--- Calling toStringWithConsume() ---\n"); 
            System.out.println(elem.toStringWithConsume()); 

            xmlString = 
                "<outerTag xmlns=\"http://someNamespace\">" + 
                    "<innerTag>" + 
                        "<node1>Hello</node1>" + 
                        "<node2>Hello</node2>" + 
                   "</innerTag>" + 
                "</outerTag>"; 

            elem = AXIOMUtil.stringToOM(xmlString); 
            System.out.println("\n--- Calling toString() ---\n"); 
            System.out.println(elem.toString()); 
        } 
        catch(Exception e) { 
            e.printStackTrace(); 
        } 
    } 
} 


The output of this program is this (I added line breaks in the XML for
easier readability): 

--- Calling toStringWithConsume() --- 

<outerTag xmlns="http://someNamespace"> 
    <innerTag xmlns="http://someNamespace"> 
        <node1 xmlns="http://someNamespace">Hello</node1> 
        <node2 xmlns="http://someNamespace">Hello</node2> 
    </innerTag> 
</outerTag> 

--- Calling toString() --- 

<outerTag xmlns="http://someNamespace"> 
    <innerTag> 
        <node1>Hello</node1> 
        <node2>Hello</node2> 
    </innerTag> 
</outerTag> 

I consider this a very big problem for me, because we return very large XML
results, and this bloats the XML tremendously.  I had to refrain from using
default namespaces because of this.  I really hope this can be corrected in
time for the next release of Axis2 / AXIOM.


Deepal Jayasinghe-2 wrote:
> 
> I will be looking to it and try to give you a fix.
> Thanks
> Deepal
>> Hello,
>>
>> I am struggling with what seems to be a bug in the AXIOM API.  There
>> appears
>> to be no way to declare a default namespace in the parent node, and have
>> this propagate down to the child elements.  In other words, I am trying
>> to
>> declare a default namespace in the parent node, and have the child nodes
>> automatically belong to that namespace.  I created a JIRA more than 2
>> months
>> ago, but it still seems like nobody even looked at it.  I also tried
>> emailing Apache, but I get no response.  Here is the original JIRA
>> submission.  Any help would be appreciated!
>>
>>                  Key: AXIS2-3156
>>                  URL: https://issues.apache.org/jira/browse/AXIS2-3156
>>              Project: Axis 2.0 (Axis2)
>>           Issue Type: Bug
>>           Components: om
>>     Affects Versions: 1.3
>>          Environment: Microsoft Windows 2003 Server, Java 1.5.0_11. Axis2
>> version 1.3 (uses AXIOM version 1.2.5). 
>>             Reporter: Yechiel Mondrowitz
>>              Fix For: 1.3
>>
>>
>> When calling declareDefaultNamespace() on a parent node, AXIOM assignes a
>> blank namespace on the first level's child element.  So if XML is passed
>> to
>> AXIOM that looks like this:
>>
>> <outerTag>
>>     <innerTag>
>>         <node1>Hello</node1>
>>         <node2>Hello</node2>
>>     </innerTag>
>> </outerTag>
>>
>> And then declareDefaultNamespace() of "http://someNamespace" is called on
>> the <outerTag>, the resulting XML will be this:
>>
>> <outerTag xmlns="http://someNamespace">
>>     <innerTag xmlns="">
>>         <node1>Hello</node1>
>>         <node2>Hello</node2>
>>     </innerTag>
>> </outerTag>
>>
>> Notice the xmlns="" declared in the <innerTag>.  According to my
>> understanding of XML namespaces, the <innerTag> and its child nodes will
>> no
>> longer belong to the parent namespace of "http://someNamespace", since it
>> explicitly overrides it with an empty namespace.  So <innerTag> and its
>> child nodes will in fact not belong to any namespace!  Here is a small
>> program to illustrate:
>>
>> import org.apache.axiom.om.*;
>> import org.apache.axiom.om.impl.llom.util.*;
>>
>> public class Test2 {
>>     public static void main(String [] args) {
>>         try {
>>             String xmlString =
>>                 "<outerTag>" +
>>                     "<innerTag>" +
>>                         "<node1>Hello</node1>" +
>>                         "<node2>Hello</node2>" +
>>                    "</innerTag>" +
>>                 "</outerTag>";
>>
>>             OMElement elem = AXIOMUtil.stringToOM(xmlString);
>>             elem.declareDefaultNamespace("http://someNamespace");
>>             System.out.println(elem.toString());
>>         }
>>         catch(Exception e) {
>>             e.printStackTrace();
>>         }
>>     }
>> }
>>
>> The output of this program is this (I added line breaks in the XML for
>> easier readability):
>>
>> <outerTag xmlns="http://someNamespace">
>>     <innerTag xmlns="">
>>         <node1>Hello</node1>
>>         <node2>Hello</node2>
>>     </innerTag>
>> </outerTag>
>>
>> As you can see, the <innerTag> was assigned xmlns="" by AXIOM.
>>
>>   
> 
> 
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