XML Document memory usage

  • Thread starter Thread starter not_a_commie
  • Start date Start date
N

not_a_commie

Here is my goal:

1. Read in a (really large) UTF8 XML document.
2. Put a certain element in that document into a byte[] still encoded
in UTF8.
3. Avoid ever converting the document or any of its significant
children into UTF16.

If I load my document using an XmlReader passed into XDocument.Load
(or XmlDocument.Load) does it leave it in the original format until I
call some method that returns a string? Is there some type of reader
that would have this behavior?

As far as extracting the element, my first thought was to use an
XmlWriter into a MemoryStream (with the above assumption that my
document hadn't already been converted into UTF16). However, I can't
get an appropriately-sized byte[] out of it that way without making a
copy after I've written the data. Hence, I've used at least 2x memory
anyway with that approach. Any ideas?
 
not_a_commie said:
Here is my goal:

1. Read in a (really large) UTF8 XML document.
2. Put a certain element in that document into a byte[] still encoded
in UTF8.
3. Avoid ever converting the document or any of its significant
children into UTF16.

If I load my document using an XmlReader passed into XDocument.Load
(or XmlDocument.Load) does it leave it in the original format until I
call some method that returns a string? Is there some type of reader
that would have this behavior?
Click to expand...

XmlReader exposes .NET strings (e.g. the Value property), as do XmlNode
(e.g. InnerText or Value) as do XElement/XDocument (e.g. Value
property). You are not dealing with bytes at all that way.
So whether the original XML document is UTF-8 or UTF-16 or another
encoding, all those APIs give you .NET strings (which are sequences of
UTF-16 encoded characters). If you want the original bytes then you need
a FileStream.
 
Yes, I recognize that all that everything is exposed as strings in the
XML classes. I'm asking: does the XML classes store the data
internally as strings as well? In other words, does it build up utf16
strings as it parses the input?
 
not_a_commie said:
Yes, I recognize that all that everything is exposed as strings in the
XML classes. I'm asking: does the XML classes store the data
internally as strings as well? In other words, does it build up utf16
strings as it parses the input?
Click to expand...

I have never looked at the implementation but I am sure the DOM
(XmlDocument/XmlElement/XmlNode) and LINQ to XML
(XDocument/XElement/XNode) store .NET strings, it does not make any
sense to store bytes in different encodings and to decode any time a
Value property or Name property is accessed.
 
Back
Top