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Serialize error

Hiiii All

System.Runtime.Serialization.SerializationException: No top object.

What is scary is that it seems to happen at random with the same code (it
works most of the time, but not all of the time). Are there any known bugs
with MemoryStreams or Serialization? The code looks like this:

Public Function Read_Object_From_File(ByVal FileName As String) As Object

Dim Ob As Object

Try

Dim FStream As New IO.FileStream(FileName, IO.FileMode.Open, IO.FileAccess.Read)

Dim Binary_Formater As New System.Runtime.Serialization.Formatters.Binary.BinaryFormatter

Ob = Binary_Formater.Deserialize(FStream)

FStream.Close()

Return Ob

Catch ex As Runtime.Serialization.SerializationException

Get_Exception_Massege(ex)

Catch ex As Exception

Return Nothing

End Try

Return Nothing

End Function

Edited byOra-dbaabode Wednesday, July 29, 2009 10:24 AM

Ora-dbaabode

Hiii Aaaaaaalllllllll

Please Anybady

Ora-dbaabode

Hi,
I had similar problem when I was trying to deserialize from MemoryStream, something about invalid first element.
Solution was to set location to 0, for ex

memoryStream.Location=0;

and then call deserialize.

In your case try

FStream.Location = 0;
Ob = Binary_Formater.Deserialize(FStream);

Milan Erić

thank you milan

I will try this ,

Ora-dbaabode

hi milan

I don't find location property in memoryStream Class

Ora-dbaabode

Sorry, my bad :(
Property name is Position, not Location..

Milan Erić

I find it

Ora-dbaabode

sorry,that isn't useful

Ora-dbaabode

I had a similar problem, but I was using CryptoStream, FileStream and BinaryFormatter.
The following resolved the issue for me: prior to serializing the objects, I wrote a few characters into the stream, so I know where the beginning is. Then when I deserialize the objects I just need to read past these characters prior to beginning the deserialization.

The below examples are in c#, but you should get the idea of what I mean by writing a few characters into the stream.

//Below is a snippet from my serilization method

fs = new FileStream(mySavePath, FileMode.Create);
fs.Write(Encoding.ASCII.GetBytes("CRYPT"), 0, 5);
cs = new CryptoStream(fs, desCypher.CreateEncryptor(key, iv), CryptoStreamMode.Write);
bf = new BinaryFormatter();
bf.Context = new StreamingContext(StreamingContextStates.File);
bf.AssemblyFormat = FormatterAssemblyStyle.Simple;
bf.FilterLevel = TypeFilterLevel.Full;
bf.TypeFormat = FormatterTypeStyle.TypesAlways;

bf.Serialize(cs, myListToSave);
cs.FlushFinalBlock();

//Below is a snippet from my deserilization method

bf = new BinaryFormatter();
bf.Context = new StreamingContext(StreamingContextStates.File);
bf.AssemblyFormat = FormatterAssemblyStyle.Simple;
bf.FilterLevel = TypeFilterLevel.Full;
bf.TypeFormat = FormatterTypeStyle.TypesAlways;

fs = new FileStream(mySavePath, FileMode.Open, FileAccess.Read, FileShare.Read);
fs.Position = 5;
int length = (int)fs.Length;

byte[] encryptedBytes = new byte[fs.Length];
fs.Read(encryptedBytes, 0, length - 5);
fs.Position = 5;

cs = new CryptoStream(fs, decryptor, CryptoStreamMode.Read);

tempList = (myInfoList)bf.Deserialize((Stream)cs);

jkramer001

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