Am Donnerstag, 28. April 2005 12:32 schrieb 
[EMAIL PROTECTED]:
> Hi,
>
> I have couple of questions regarding Xerces and Xalan
>
> First one is why do we have to use these lines , whats the importance
> of usign it ? Is this compulsory
>
>     XALAN_USING_XALAN(XalanDocument)
>     XALAN_USING_XALAN(XPathEvaluator)
>     XALAN_USING_XERCES(XMLPlatformUtils)
>     XALAN_USING_XERCES(MemBufInputSource)
>     XALAN_USING_XALAN(XalanDOMString)
>     XALAN_USING_XALAN(XalanNode)
>     XALAN_USING_XALAN(XalanSourceTreeInit)
>     XALAN_USING_XALAN(XalanSourceTreeDOMSupport)
>     XALAN_USING_XALAN(XalanSourceTreeParserLiaison)
>     XALAN_USING_XALAN(XObjectPtr)
>     XALAN_USING_XALAN(NodeRefList)
>     XALAN_USING_XERCES(LocalFileInputSource)

Hi Praveen,

these macros are wrappers for the 'using'-directive, if namespaces are 
supported by your compiler, empty otherwise.

>
> Second One ,
>
> We are tryign to write a program to perform following things
> 1. We want to get the value of each tag , modify an XML tag if
> necessary , delete an XML tag and store it back to the same XML file.

Generally, in-file manipulations are a bad idea. You should consider 
processing the source file read-only first, and store the results in a 
different tempfile. As a second step, you can move the tempfile to the 
name of the original source.

> 2. I need to do an XML transformation.

This is what xalan is for.

> 3. I need to do an XML validation.

Validation is a matter of enabling validation during parsing. There is 
no method similar to 'validate this piece of XML'.

> 4. I need to find the difference between two XML files. It could in
> ordered or unordered.

This task can become rather difficult!

> 1. In the second case what and all need to be initialised ?
>
> 2. Are there any API's to find the difference between two XML files
> or do I have to perform these things on my own.

There is no standard describing the difference between two XML files. In 
fact, you can choose rather different measures about what counts as a 
difference and what does not. In the simplest case, you run 'diff' and 
get the text-based differences - but this might not be what you intend. 
In all other cases you have to compare two representations (e.g. DOM 
trees) against each others and find the differences according to your 
preferred rules.

> 3. Should I use DOM or SAX ?

In order to perform a rule-based content difference checker, I would 
prefer DOM, since the algorithms can be recursive, and you can 
formulate just any rules. (But I may be wrong here, because I have only 
little experience with SAX).

> 4. I heard both Xalan DOM and Xerces DOM is present , Which one
> should I use ?
>
> 5. How to use only Xerces DOM or only Xalan DOM ?

If you want to perform XML-stylesheet processing, there is no need to 
program it again. You can use the Xalan executable as a simple 
transformation tool.

On the other hand, if your application is required to perform stylesheet 
processing by it's own, there is no need to use a second DOM 
representation. Xalan accepts both DOM variants as input.

> 6. Is Memory Manager necessary ? if yes please provide me the sample
> code on how to use it ?

It's not necessary to use a custom MemoryManager, as memory management 
falls back to stdlib-behaviour. However, if you encounter performance 
issues, MemoryManager may help you.


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Institut f�r Informatik
Signalverarbeitung und Mustererkennung
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