Custom file DeSerialization and file access

[Nadav]

Hi,

I have to read files generated by 3rd party application, these files are in
a propriotary format ( not generated using the .NET framework ), I want to
implement a custom DeSerializer to read the data in the file, I wonder is it
possible to read files in this manner ( e.g. custom implementation of the
ISerializable interface )? is this right way to extract data from the file?
OR should I rather 'manually' use the FileStream to read the desiered chunks
of data?

Another Issue, is there a C# equivalent to the unmanaged CreateFileMappi ng,
MapViewOfFile ??? accessing files in this manner dramatically impove
performance as the kernel is resposible for loading the data from the disk (
and not the application ) so less context switch are done between the
application layer and the kernel...

--
Nadav
http://www.ddevel.com

[Sahil Malik]

Nadav,

While this certainly could be acheived using ISerializable, there is no
point in doing so. ISerializable's purpose is to implement custom
serialization - so that IFormatter (BinaryFormatte r for example), can call
the proper constructor and the proper GetObjectData - in your case you are
probably better off implementing the "deserializatio n" to .NET via a non
ISerializable or Serializable mechanism.

Secondly,

Kernel32.Dll->CreateFileMapp ing and
Kernel32.Dll->MapViewOfFil e ..

AFAIK donot have managed implementations .

But they can be easily used in C# like this --

[DllImport("kern el32.dll", SetLastError=tr ue)]
static extern IntPtr CreateFileMappi ng(IntPtr hFile,
IntPtr lpFileMappingAt tributes, PageProtection flProtect, uint
dwMaximumSizeHi gh,
uint dwMaximumSizeLo w, string lpName);

and

[DllImport("kern el32.dll")]
static extern IntPtr MapViewOfFile(I ntPtr hFileMappingObj ect, uint
dwDesiredAccess , uint dwFileOffsetHig h, uint dwFileOffsetLow ,
UIntPtr dwNumberOfBytes ToMap);

TTFN :-)

- Sahil Malik
http://dotnetjunkies.com/weblog/sahilmalik
"Nadav" <Na***@discussi ons.microsoft.c om> wrote in message
news:F6******** *************** ***********@mic rosoft.com...

Hi,

I have to read files generated by 3rd party application, these files are
in
a propriotary format ( not generated using the .NET framework ), I want to
implement a custom DeSerializer to read the data in the file, I wonder is
it
possible to read files in this manner ( e.g. custom implementation of the
ISerializable interface )? is this right way to extract data from the
file?
OR should I rather 'manually' use the FileStream to read the desiered
chunks
of data?

Another Issue, is there a C# equivalent to the unmanaged
CreateFileMappi ng,
??? accessing files in this manner dramatically impove
performance as the kernel is resposible for loading the data from the disk
(
and not the application ) so less context switch are done between the
application layer and the kernel...

--
Nadav
http://www.ddevel.com

[Nadav]

Sahil,

Thanks for you immediate responce, concerning the FileMapping issue, indeed
it is possible to use these APIs through DllImport BUT all access to the
mapped data would have to be done in an unsafe manner, therefor it is not
posibble to reffer to the mapped data directly as can be done in C++ ( by
pointers ), my guess is that usage of the file mapping API should be done
only in the unmanaged world....

Nadav.

"Sahil Malik" wrote:

Nadav,

While this certainly could be acheived using ISerializable, there is no
point in doing so. ISerializable's purpose is to implement custom
serialization - so that IFormatter (BinaryFormatte r for example), can call
the proper constructor and the proper GetObjectData - in your case you are
probably better off implementing the "deserializatio n" to .NET via a non
ISerializable or Serializable mechanism.

Secondly,

Kernel32.Dll->CreateFileMapp ing and
Kernel32.Dll->MapViewOfFil e ..

AFAIK donot have managed implementations .

But they can be easily used in C# like this --

[DllImport("kern el32.dll", SetLastError=tr ue)]
static extern IntPtr CreateFileMappi ng(IntPtr hFile,
IntPtr lpFileMappingAt tributes, PageProtection flProtect, uint
dwMaximumSizeHi gh,
uint dwMaximumSizeLo w, string lpName);

and

[DllImport("kern el32.dll")]
static extern IntPtr MapViewOfFile(I ntPtr hFileMappingObj ect, uint
dwDesiredAccess , uint dwFileOffsetHig h, uint dwFileOffsetLow ,
UIntPtr dwNumberOfBytes ToMap);

TTFN :-)

- Sahil Malik
http://dotnetjunkies.com/weblog/sahilmalik
"Nadav" <Na***@discussi ons.microsoft.c om> wrote in message
news:F6******** *************** ***********@mic rosoft.com...

Hi,

I have to read files generated by 3rd party application, these files are
in
a propriotary format ( not generated using the .NET framework ), I want to
implement a custom DeSerializer to read the data in the file, I wonder is
it
possible to read files in this manner ( e.g. custom implementation of the
ISerializable interface )? is this right way to extract data from the
file?
OR should I rather 'manually' use the FileStream to read the desiered
chunks
of data?

Another Issue, is there a C# equivalent to the unmanaged
CreateFileMappi ng,
??? accessing files in this manner dramatically impove
performance as the kernel is resposible for loading the data from the disk
(
and not the application ) so less context switch are done between the
application layer and the kernel...

--
Nadav
http://www.ddevel.com

[Sahil Malik]

Nadav,

Good news. You can do pointer operations in C# using the unsafe keyword. I
am using Kernel32.dll->MoveMemory happily in a heavily used caching block I
wrote for a windows service that gets hit a few thousand times a second in
an enterprise block.

You have to compile this with the /unsafe option, but it works.

- Sahil Malik
http://dotnetjunkies.com/weblog/sahilmalik
"Nadav" <Na***@discussi ons.microsoft.c om> wrote in message
news:ED******** *************** ***********@mic rosoft.com...

Sahil,

Thanks for you immediate responce, concerning the FileMapping issue,
indeed
it is possible to use these APIs through DllImport BUT all access to the
mapped data would have to be done in an unsafe manner, therefor it is not
posibble to reffer to the mapped data directly as can be done in C++ ( by
pointers ), my guess is that usage of the file mapping API should be done
only in the unmanaged world....

Nadav.

"Sahil Malik" wrote:

Nadav,

While this certainly could be acheived using ISerializable, there is no
point in doing so. ISerializable's purpose is to implement custom
serialization - so that IFormatter (BinaryFormatte r for example), can
call
the proper constructor and the proper GetObjectData - in your case you
are
probably better off implementing the "deserializatio n" to .NET via a non
ISerializable or Serializable mechanism.

Secondly,

Kernel32.Dll->CreateFileMapp ing and
Kernel32.Dll->MapViewOfFil e ..

AFAIK donot have managed implementations .

But they can be easily used in C# like this --

[DllImport("kern el32.dll", SetLastError=tr ue)]
static extern IntPtr CreateFileMappi ng(IntPtr hFile,
IntPtr lpFileMappingAt tributes, PageProtection flProtect, uint
dwMaximumSizeHi gh,
uint dwMaximumSizeLo w, string lpName);

and

[DllImport("kern el32.dll")]
static extern IntPtr MapViewOfFile(I ntPtr hFileMappingObj ect, uint
dwDesiredAccess , uint dwFileOffsetHig h, uint dwFileOffsetLow ,
UIntPtr dwNumberOfBytes ToMap);

TTFN :-)

- Sahil Malik
http://dotnetjunkies.com/weblog/sahilmalik
"Nadav" <Na***@discussi ons.microsoft.c om> wrote in message
news:F6******** *************** ***********@mic rosoft.com...

> Hi,
>
> I have to read files generated by 3rd party application, these files
> are
> in
> a propriotary format ( not generated using the .NET framework ), I want
> to
> implement a custom DeSerializer to read the data in the file, I wonder
> is
> it
> possible to read files in this manner ( e.g. custom implementation of
> the
> ISerializable interface )? is this right way to extract data from the
> file?
> OR should I rather 'manually' use the FileStream to read the desiered
> chunks
> of data?
>
> Another Issue, is there a C# equivalent to the unmanaged
> CreateFileMappi ng,
> ??? accessing files in this manner dramatically impove
> performance as the kernel is resposible for loading the data from the
> disk
> (
> and not the application ) so less context switch are done between the
> application layer and the kernel...
>
> --
> Nadav
> http://www.ddevel.com