XPath Query by namespace

[Clay]

I'm trying to find the most efficient way to query specific nodes from an xml
document using vb.net. My app will receive various types of xml documents
and there are child nodes that will always exist that I need to retrieve data
from before processing the whole document.

There are several different root elements that can be sent, but within the
document there will always be a 'DataAreaToQuery' node. The
'DataAreaToQuery' child node will not always be the first child node off the
root; it may be two levels deep.

Ultimately what I’m looking for is to get the root element by namespace.
The namespace for 'DataAreaToQuery' will always be the same and unique to the
rest of the document.

Thanks in advance for your input.

Sample XML:
<?xml version="1.0" encoding="UTF-8"?>
<OneOfManyRootElementNames
xmlns="http://OneOfManyRootElementNames/ns"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<st:DataAreaToQuery xmlns:st="http://dataareatoquery/ns">
<st:ApplicationArea>
<st:Sender>
<st:LogicalId>String</st:LogicalId>
<st:Component>String</st:Component>
<st:Task>String</st:Task>
<st:ReferenceId>String</st:ReferenceId>
<st:AuthorizationId>String</st:AuthorizationId>
<st:CreatorNameCode>String</st:CreatorNameCode>
<st:SenderNameCode>AF</st:SenderNameCode>
<st:SenderURI>http://www.altova.com</st:SenderURI>
</st:Sender>
<st:Destination>
<st:DestinationNameCode>AF</st:DestinationNameCode>
<st:DestinationURI>http://www.altova.com</st:DestinationURI>
<st:DestinationSoftwareCode>String</st:DestinationSoftwareCode>
<st:DestinationSoftware>String</st:DestinationSoftware>
</st:Destination>
</st:ApplicationArea>
</st:DataAreaToQuery>
<st:DataArea1/>
<st:DataArea2/>
<st:DataArea3/>
</OneOfManyRootElementNames>

[Oleg Tkachenko [MVP]]

Clay wrote:

I'm trying to find the most efficient way to query specific nodes from an xml
document using vb.net. My app will receive various types of xml documents
and there are child nodes that will always exist that I need to retrieve data
from before processing the whole document.

There are several different root elements that can be sent, but within the
document there will always be a 'DataAreaToQuery' node. The
'DataAreaToQuery' child node will not always be the first child node off the
root; it may be two levels deep.

Ultimately what I’m looking for is to get the root element by namespace.
The namespace for 'DataAreaToQuery' will always be the same and unique to the
rest of the document.

It's just "//st:DataAreaToQuery" query (bind st prefix using
XmlNamespaceManager). Or (long form) use
//*[local-name()='DataAreaToQuery' and
namespace-uri()='http://dataareatoquery/ns']

--
Oleg Tkachenko [XML MVP]
http://blog.tkachenko.com