Best approach for xpath on .NET 2.0

[David Thielen]

Hi;

I need to perform xpath queries on xml under .net 2.0 (ok if it won't run
under 1.1). What is the approach that will give me the fastest code?

These xpath queries will walk all over the xml - it is not a case where each
query usually occurs further down the xml from the previous query. And there
will tend to be a lot of queries on each dataset.

--
thanks - dave

[Kevin Yu [MSFT]]

Hi Dave,

First of all, I would like to confirm my understanding of your issue. From
your description, I understand that you need to perform an XPath query on a
DataSet. If there is any misunderstanding, please feel free to let me know.

Here is a very good article dedicated on how to perform an XPath query on a
DataSet. Please check it and it will be helpful.

http://msdn2.microsoft.com/en-us/library/89tyw6dw

HTH.

Kevin Yu
=======
"This posting is provided "AS IS" with no warranties, and confers no
rights."

[David Thielen]

Hello;

Sorry - I should not have used the word dataset. My xml will always come
from a Stream - usually a file.

--
thanks - dave
"Kevin Yu [MSFT]" wrote:

Hi Dave,

First of all, I would like to confirm my understanding of your issue. From
your description, I understand that you need to perform an XPath query on a
DataSet. If there is any misunderstanding, please feel free to let me know.

Here is a very good article dedicated on how to perform an XPath query on a
DataSet. Please check it and it will be helpful.

http://msdn2.microsoft.com/en-us/library/89tyw6dw

HTH.

Kevin Yu
=======
"This posting is provided "AS IS" with no warranties, and confers no
rights."

[Kevin Yu [MSFT]]

Hi dave,

Doing XQuery in an XmlDocument is generally the same as mentioned in the
article I have provided. If you're getting the xml from a file, you can
first load it into an XmlDocument and then use XmlDocument.SelectNodes with
an xpath as argument to do the query. It is also the same as we did in .NET
1.1. Please also check the following link for more informatioin on
SelectNodes method.

http://msdn2.microsoft.com/en-us/library/hcebdtae

Kevin Yu
=======
"This posting is provided "AS IS" with no warranties, and confers no
rights."

[David Thielen]

Hello;

So XmlDocument is more efficient than XpathDocument? Ok, will go that route.

Out of curiosity why do they have XpathDocument then?

--
thanks - dave
"Kevin Yu [MSFT]" wrote:

Hi dave,

Doing XQuery in an XmlDocument is generally the same as mentioned in the
article I have provided. If you're getting the xml from a file, you can
first load it into an XmlDocument and then use XmlDocument.SelectNodes with
an xpath as argument to do the query. It is also the same as we did in .NET
1.1. Please also check the following link for more informatioin on
SelectNodes method.

http://msdn2.microsoft.com/en-us/library/hcebdtae

Kevin Yu
=======
"This posting is provided "AS IS" with no warranties, and confers no
rights."

[Martin Honnen]

David Thielen wrote:

So XmlDocument is more efficient than XpathDocument?

No, XPathDocument is optimized for readonly XPath access. You only need
XmlDocument if you want to make changes to the XML.
--

Martin Honnen --- MVP XML
http://JavaScript.FAQTs.com/

[David Thielen]

Hi;

That's what I thought. But Kevin Yu is, I am assuming, posting the official
MS suggestion. Any idea why he would prefer XmlDocument?

My use is xpath quieries only - so it is read-only.

--
thanks - dave
"Martin Honnen" wrote:

David Thielen wrote:

So XmlDocument is more efficient than XpathDocument?

No, XPathDocument is optimized for readonly XPath access. You only need
XmlDocument if you want to make changes to the XML.
--

Martin Honnen --- MVP XML
http://JavaScript.FAQTs.com/

[Kevin Yu [MSFT]]

Hi dave,

I think there might be some misunderstanding here. Using XmlDocument or
XpathDocument depends on the scenario. As Martin said, in an readonly case,
we can use xpathdocument, however, if you need to do modifications, use
XmlDocument.

Kevin Yu
=======
"This posting is provided "AS IS" with no warranties, and confers no
rights."

[David Thielen]

Hi;

Can I assume that for the read-only case XpathDocument is faster?

--
thanks - dave
"Kevin Yu [MSFT]" wrote:

Hi dave,

I think there might be some misunderstanding here. Using XmlDocument or
XpathDocument depends on the scenario. As Martin said, in an readonly case,
we can use xpathdocument, however, if you need to do modifications, use
XmlDocument.

Kevin Yu
=======
"This posting is provided "AS IS" with no warranties, and confers no
rights."

[Oleg Tkachenko [MVP]]

David Thielen wrote:

Can I assume that for the read-only case XpathDocument is faster?

Sure. It's 30-50% faster than XmlDocument for XPath. Not to mention it
takes less memory.

--
Oleg Tkachenko [XML MVP, MCAD]
http://www.xmllab.net
http://blog.tkachenko.com