Re: Serialization and Deserialization

From: Amadelle (amadelle_at_yahoo.com)
Date: 10/07/04 

Date: Thu, 7 Oct 2004 15:28:11 -0700

Ok this was a good suggestion, still didn't solve my problem though ..
I think you are absolutely right though Robert in the fact that the part
that I am messing up is getting the binary data from the database.
Several things that I noticed:
1- When I serialize the object the byte array that I generate has a size
(length) of 2700+. But when I get the array of bytes back it is only the
buffer size of 100
so the outbyte is never larger than the 100 which makes sense since I have a
line of code byte[] outbyte = new byte[buffersize] and buffersize being 100
explains why the lengths are never the same. So i tried to fix this problem
by using the buffer size of 8000. But even extending the buffer size didn't
solve my problem. So given my code, it seems that I am still not populating
the array of bytes correctly (I used your code change suggestions but that
didn't solve my problem either).
2- Next step .. I noticed that all of the array items in the byte array
generated after the serialization usually have a value in the form of number
associated with them. so for example arrBytes[2] has a value of 255. But
when I get the array back regardless of the size (100 vs. 2700), even the
first 100 all come back with values of 0. Further, in the code, I use a
variable called retval which is supposed to represent the bytes returned
from the GetBytes method of datareader. This retval always comes back with
a value of 1. So the loop for going from retval to buffer size pretty much
stops after the first round.

In the database I am using varbinary to store this binary data, and I know
that the size of this field is only 8000 bytes max. So here is the part
that I get fuzzy. I am not so sure whether my data gets cut down due to the
field limitations in SQL .... or am I doing something else wrong in the
calls that I make to read the data back from the database?

This is too complicated and I don't really understand the binary data and
how the sizes work in relation to the byte array, data type var binary, how
to read it back, etc. So any help would be great... if someone can also
direct me to the right location, documentation to read up on the issue as
well, that would be great too..

Thanks again in advance,

Amadelle

"Robert Jordan" <robertj@gmx.net> wrote in message
news:ck4cbb$l67$05$1@news.t-online.com...
> Hi Amadelle,
>
> > Hi all and thanks in advance for your help,
> >
> > I am having problems deserializing an object which seems to be
serializing just fine. I save the byte array of the serialized object in
the database (when I check the database the field that holds the binary data
seems populated), but when I want to deserialize this same byte array the
application fails and gives me the following error:
> >
> > Binary stream does not contain a valid BinaryHeader, 0 possible causes,
invalid stream or object version change between serialization and
deserialization.
> >
> > Here is the code that I am using for serialization:
>
> The serialization & deserialization code is ok, but ...
>
>
> > One more thing: I am using the following code to get and set the binary
data in the database (ofcourse I am not showing the whole code but how I set
the parameters and how I get the results back)
> > To Get:
> > int bufferSize = 100;
> >
> > byte[] outbyte = new byte[bufferSize]; // The BLOB byte[] buffer to be
filled by GetBytes
> >
> > long retval; // The bytes returned from GetBytes.
> >
> > long startIndex = 0;
> >
> > retval = objDataReader.GetBytes((int)ColumnIndex.FilterObjects,
startIndex, outbyte, 0, bufferSize);
> >
> >
> > // Continue reading while there are bytes beyond the size of the buffer.
> >
>
> that's wrong. use while (retval > 0 && retval <= bufferSize)
>
> > while (retval == bufferSize)
> >
> > {
> >
> > // Reposition the start index to the end of the last buffer and fill the
buffer.
> >
> > startIndex += bufferSize;
>
> here startIndex += retval.
>
> >
> > retval = objDataReader.GetBytes((int)ColumnIndex.FilterObjects,
startIndex, outbyte, 0, bufferSize);
> >
> > }
> >
> > objFilterUser.FilterObjects = outbyte;
> >
> >
> >
> > To Set:
> >
> > aryParamList.Add("@FilterObjects", DbType.Binary, 50,
objFilterUser.FilterObjects);
> >
>
> bye
> Rob

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