Re: [bdbxml] namespace problem

sarigiannis xaralampos wrote:
> Thanks George for the answer indeed I instantiate a single XmlManager 
> object, and keep it around for
> 
> the lifetime of my application  but I don t do the same with the 
> XmlQueryExpression .
> 
> You mean to create once an XmlQueryExpression lalas= new 
> XmlQueryExpression();  and use this variable whenever i need to make a 
> query instead of initializing new XmlQueryExpression variables all the 
> times you need to make a query?? (indeed XMLDB objects are very heavy it 
> s good as I realised everytime I create sth like XmlQueryExpression to 
> delete them  )

You can do that, but it won't gain you very much. What my colleague 
meant was that if you were going to run the same query a number of times 
(even in a number of different threads), you could do this by 
pre-parsing the query to an XmlQueryExpression object, and calling 
XmlQueryExpression::execute() many times over.

If you do this from different threads, you will need to use an 
XmlQueryContext for each thread, as these cannot be shared across threads.

> Anyway
> 
> I have one problem when using the below type of namespace :
> 
> <assessmentItem xmlns="http://www.imsglobal.org/xsd/imsqti_v2p0"
> 
>    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
> 
>    xsi:schemaLocation=" http://www.imsglobal.org/xsd/imsqti_v2p0 
> imsqti_v2p0.xsd 
> <http://www.imsglobal.org/xsd/imsqti_v2p0%20imsqti_v2p0.xsd> 
> "title="Unattended Luggage" >
> 
>  
> 
> in order I make xqueries I instantiate an Xmlquerycontext
> 
>  
> 
>  context.setNamespace(" ", "http://www.imsglobal.org/xsd/imsqti_v2p0");

This is not allowed. I believe what you are trying to do is to set the 
default element namespace for the query - but BDB XML does not currently 
provide a way for users to do this. Instead, you will need to bind a 
prefix to the namespace like this:

context.setNamespace("ims", "http://www.imsglobal.org/xsd/imsqti_v2p0");

And use the prefix in you query, ie:

/ims:assessmentItem

/ims:assessmentItem[@title='Unattended Luggage']

> when my query has the form for instance   / assessmentItem  it does work
> 
> when my query has the form for instance   / assessmentItem/[@title=’ 
> Unattended Luggage’]  it does  not work :((

I hope this helps,

John Snelson

-- 
John Snelson, Berkeley DB XML Engineer
Sleepycat Software, Inc
http://www.sleepycat.com

Contracted to Sleepycat through Parthenon Computing Ltd
http://blog.parthcomp.com/dbxml


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