MemoryStream vs. FileStream

[nhoellei]

I am running into an odd situation in dealing with Memorystreams. In
my program, I create an in-memory XML document by using XMLTextWriter
pointing to a memorystream. As a quick test I dumped the stream to a
file, but the file is was truncated by 9 bytes. I skipped the
memorystream a wrote directly to a filestream object, everything
appears OK.


I instantiate the memorystream as 0 bytes, when fully loaded the stream
capacity is 131456 bytes.


Any ideas as to why the Memorystream is not including all the data? I
have also tried explicitly setting the size of the stream beyond the
potential size to no avail.


Code snippets:


MemoryStream ms = new MemoryStream(0);
ms.Seek(0,SeekOrigin.Begin);
XmlTextWriter _xwrite = new
XmlTextWriter(ms,System.Text.Encoding.UTF8);
_xwrite.Formatting = Formatting.Indented;
_xwrite.IndentChar = '\x0009';
_xwrite.WriteStartElement("ESDSubnets");
.....
_xwrite.WriteEndElement();


FileStream fs = new
FileStream(@"C:\Temp\ESDLocations.XML",FileMode.Create);


byte[] b = ms.GetBuffer();
fs.Write(b,0,ms.ToArray().Length);


ms.Flush();
_xwrite.Close();


(both these methods appears to lop off 9 bytes)
FileStream fs = new FileStream(filename,filemode.create);
ms.WriteTo(fs);


OR


FileStream fs = new FileStream(filename,filemode.create);
fs.Write(ms.getBuffer(),0,ms.ToArray().Length);

 

[NeilTrain]

my first question would be, are the 9 bytes important? I mean if I lost 9 bytes when saving to file, I would only care if I could not open the xml file later on. Don't waste a bunch of time chasing a trivial issue.

 

[nhoellei]

Yes, the last 9 bytes are important. It creates a malformed XML document and saving to a file is a parameter on execution.

Here's what it leaves off:

...
<Subnet Gateway="0.0.0.0.">
<ESDServers>1</ESDServers>
<ESDSRV0>ServerNmae</ESDSRV0>
</Subnet>
</ESDSubnets> (...Root Element...)

 

[chiph]

I see you're flushing the memory stream. Are you flushing the filestream as well?

Chip H.


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[nhoellei]

I am getting closer. Thanks for the suggestion, chiph. If I flush the filestream, it only leaves off 2 bytes. I also tried flushing the XMLTextWriter, but ended up with the same result.

 

[chiph]

It's possible that the XmlTextWriter is dropping some of the whitespace that wouldn't affect the Xml (excess spaces between elements, etc). Use a diff tool to compare before/after to see what's being dropped. If it's just whitespace between elements, you're fine, as that isn't needed for it to be a valid Xml document (you can have Xml all on one line if you like -- the pretty formatting just bulks up the file and makes it easy for us humans to read it).

Chip H.


____________________________________________________________________
Donate to Katrina relief:

http://s1.amazon.com/paypage/PELYGQVJ8Q7IB/103-6821258-5919825

If you want to get the best response to a question, please read FAQ222-2244 first