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callback function only getting called once then program crashing

rjs1 431-Dec-09 4:36

31-Dec-09 4:36

Hi I'm trying to program a wrapper class in C# for an unmanaged C DLL. The DLL contains a function that allows you to register a callback function so i call the register callback function and pass in my callback function, now when i call a function that uses that callback in the DLL, the function only calls it once and then my program just crashes it comes back with "ConsoleApplication1.exe has encountered a problem and needs to close. We are sorry for the inconvenience" message, the callback function only gets called once, this shouldn't happen, could this be because the garbage collector is disposing my callback function object or something ? how do i solve this problem?

Thanks.

Re: callback function only getting called once then program crashing

DaveyM6931-Dec-09 5:18

DaveyM69

31-Dec-09 5:18

We need to see the relavent code (particularly the API function C declaration, your C# implementation of it and your delegate declaration) to figure out what's going on

Dave

BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Why are you using VB6? Do you hate yourself? (Christian Graus)

Re: callback function only getting called once then program crashing

rjs1 431-Dec-09 6:20

rjs1 4

31-Dec-09 6:20

ok.

        [DllImport("ProSdk.dll", EntryPoint = "RegisterStreamDirectReadCallback", CharSet = CharSet.Unicode)]
        private static extern int _RegisterStreamDirectReadCallback(stream_direct_read_callback streamReadCallback, IntPtr context);

...

//delegate
public delegate void stream_direct_read_callback(int channelNum, Byte[] dataBuf, UInt32 length, int frameType, IntPtr context);

...

//my callback function
        public void stream_read_callback(int channelNum, Byte[] dataBuf, UInt32 length, int frameType, IntPtr context)
        {
            System.Console.WriteLine(channelNum+" channel callback func called");   
        }

...

//register callback
 stream_direct_read_callback str = new stream_direct_read_callback(stream_read_callback);

_RegisterStreamReadCallback(str, IntPtr.Zero);

is that enough information, i can give you a link to the api documentation for the dll if you want?

Re: callback function only getting called once then program crashing

Daniel Grunwald31-Dec-09 6:42

Daniel Grunwald

31-Dec-09 6:42

I would guess your definition of the delegate does not match what the unmanaged function expects (number of parameters, return value, calling convention), so stack gets corrupted when your callback function is called.

Unmanaged signature:

typedef int (*STREAM_DIRECT_READ_CALLBACK)(ULONG channelNumber,void
*DataBuf,DWORD Length,int FrameType,void *context);

Your code:

public delegate void stream_direct_read_callback(int channelNum, Byte[] dataBuf, UInt32 length, int frameType, IntPtr context);

You used byte[] where the unmanaged code used void*. AFAIK the marshaller will automatically convert byte[] to void*, but NOT in the other direction as needed for callbacks. Moreover, the callback seems to be using the default calling convention (C-decl), not __stdcall as the .NET marshaller expects normally.

I would try changing the delegate signature to:

using System.Runtime.InteropServices;
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
public delegate int stream_direct_read_callback(int channelNum, IntPtr dataBuf, UInt32 length, int frameType, IntPtr context);

Re: callback function only getting called once then program crashing

rjs1 431-Dec-09 7:26

rjs1 4

31-Dec-09 7:26

thanks that worked. So the C DLL was using the C-decl calling convention then ? because i thought it was using stdcall calling convetion. So that code you put above the delegate [UnmanagedFunctionPointer(CallingConvention.Cdecl)] converts it from stdcall to C-decl then?

Is it possible to create a COM Component based on a .Net Component developed from the Compact Framework, running on Windows CE 4.2?

pdohara31-Dec-09 4:25

pdohara

31-Dec-09 4:25

I have searched the Internet and found sites that say this is possible, and others that say it is not possible. I am wondering if anyone has done it, or know a specific reason why it is not possible. This is a UI widget that we wish to make available to customers that are using an ActiveX container on Windows CE 4.2. They do not have the .Net Compact Frmaework install, but I am confident we can resolve that issue. I do not want to spend time on this if in the end it is not possible to host a .Net UI Widget within an ActiveX wrapper on Windows CE. I have read that the hosting API does not exist on CE and therefore this will not work. I am unclear what the Hosting API is, and why this means that I cannot have a COM callable wrapper for my .Net component on CE.

Tanks for your support
Pat O
<a href="http://currentchaos.blogspot.com/">Blog</a>

  _      _      _
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<ooo>  <ooo>  <ooo>

Re: Is it possible to create a COM Component based on a .Net Component developed from the Compact Framework, running on Windows CE 4.2?

#realJSOP31-Dec-09 9:14

#realJSOP

31-Dec-09 9:14

If you've found conflicting answers, be a programmer and try it yourself. Short of that, go to the best authority - MSDN - and ask your question there.

.45 ACP - because shooting twice is just silly
-----
"Why don't you tie a kerosene-soaked rag around your ankles so the ants won't climb up and eat your candy ass..." - Dale Earnhardt, 1997
-----
"The staggering layers of obscenity in your statement make it a work of art on so many levels." - J. Jystad, 2001

manirul0431-Dec-09 4:23

manirul04

31-Dec-09 4:23

ASDFGBG FDGD

Keith Barrow31-Dec-09 4:27

Keith Barrow

31-Dec-09 4:27

O MGW FT

CCC solved so far: 2 (including a Hard One!)
37!?!! - Randall, Clerks

Re: OM

OriginalGriff31-Dec-09 4:40

OriginalGriff

31-Dec-09 4:40

All those who believe in psycho kinesis, raise my hand.

Re: OM

PIEBALDconsult31-Dec-09 14:31

PIEBALDconsult

31-Dec-09 14:31

OU812!

something wrong in codes

Erdinc2731-Dec-09 3:27

Erdinc27

31-Dec-09 3:27

hi coders
i have a problem about my codes
let me tell the scenario first...i have two Forms(frm1 and frm2)...i opened frm2 by clicking a button on frm1..there is no problem till here...i want to save informations by filling the blanks on frm2 and save it but when i click save button there is nothing happen..here are my codes.. i couldnt see anything wrong in my connection or in my insert command...i need help about it

try
{
con = new SqlConnection("data source=Erdal2\\SQLEXPRESS;initial catalog=Medya;integrated security=true");

cmd = new SqlCommand("insert into Rehber (ad,soyad,firma,sektor,grup,cep_no,is_no,ev_no,fax,mail,web,msn,skype,dgm_tarih,adres,ilce,sehir,vergi_no,vrgi_daire) values (@ad,@soyad,@firma,@sektor,@grup,@cep_no,@is_no,@ev_no,@fax,@mail,@web,@msn,@skype,@dgm_tarih,@adres,@ilce,@sehir,@vergi_no,@vrgi_daire)", con);

con.Open();

cmd.Parameters.Add("@ad", SqlDbType.NVarChar).Value = txtAd.Text;
cmd.Parameters.Add("@soyad", SqlDbType.NVarChar).Value = txtSoyad.Text;
cmd.Parameters.Add("@firma", SqlDbType.NVarChar).Value = cmbFirma.SelectedItem;
cmd.Parameters.Add("@sektor", SqlDbType.NVarChar).Value = cmbSektor.SelectedItem;
cmd.Parameters.Add("@grup", SqlDbType.NVarChar).Value = txtGrup.Text;
cmd.Parameters.Add("@cep_no", SqlDbType.NVarChar).Value = txtCep.Text;
cmd.Parameters.Add("@is_no", SqlDbType.NVarChar).Value = txtisTlf.Text;
cmd.Parameters.Add("@ev_no", SqlDbType.NVarChar).Value = txtEvTlf.Text;
cmd.Parameters.Add("@fax", SqlDbType.NVarChar).Value = txtFax.Text;
cmd.Parameters.Add("@mail", SqlDbType.NVarChar).Value = txtMail.Text;
cmd.Parameters.Add("@web", SqlDbType.NVarChar).Value = txtURL.Text;
cmd.Parameters.Add("@msn", SqlDbType.NVarChar).Value = txtMSn.Text;
cmd.Parameters.Add("@skype", SqlDbType.NVarChar).Value = txtSkype.Text;
cmd.Parameters.Add("@dgm_tarih", SqlDbType.SmallDateTime).Value = dateTimePicker1.Value;
cmd.Parameters.Add("@adres", SqlDbType.NVarChar).Value = txtAdres.Text;
cmd.Parameters.Add("@ilce", SqlDbType.NVarChar).Value = txtIlce.Text;
cmd.Parameters.Add("@sehir", SqlDbType.NVarChar).Value = txtSehir.Text;
cmd.Parameters.Add("@vergi_no", SqlDbType.NVarChar).Value = txtVergiNo.Text;
cmd.Parameters.Add("@vrgi_daire", SqlDbType.NVarChar).Value = txtVergiDaire.Text;

if ((txtAd.Text != "") || (txtSoyad.Text != ""))
{
if (cmd.ExecuteNonQuery() == 1)

MessageBox.Show("Done", "Warning", MessageBoxButtons.OK, MessageBoxIcon.Warning);
else
MessageBox.Show("Error during saving processes","Warning", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
else
MessageBox.Show("There must be name and surname entered","warning",MessageBoxButtons.OK,MessageBoxIcon.Error);

i declared con and cmd as global variables...

Re: something wrong in codes

OriginalGriff31-Dec-09 3:54

OriginalGriff

31-Dec-09 3:54

If nothing at all is happening, then either it is not executing any of your code - place a breakpoint or MessageBox.Show before the "try" to check that - or it has an error and is going to your catch block - which you haven't shown.

BTW:

if ((txtAd.Text != "") || (txtSoyad.Text != ""))

does not check that both name and surname are provided - you need "&&" not "||". Your error message implies both are required.

All those who believe in psycho kinesis, raise my hand.

Re: something wrong in codes

Erdinc2731-Dec-09 4:28

Erdinc27

31-Dec-09 4:28

hii man thanks for your reply
i tried to understand about my mistake by using breakpoint
it doesnt drop in if block..i mean the block below
if ((txtAd.Text != "") && (txtSoyad.Text != ""))
{
if (cmd.ExecuteNonQuery() == 1)

MessageBox.Show("Ekleme İşlemi Tamamlandı", "Uyarı", MessageBoxButtons.OK, MessageBoxIcon.Warning);
else
MessageBox.Show("Ekleme Sırasında Hata Oluştu","Dikkat", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
else
MessageBox.Show("İsim ve Soyisim Giriniz","Dikkat",MessageBoxButtons.OK,MessageBoxIcon.Error);
}
it leaves the if control when it comes to ExecuteNonQuery() line and goes catch block.. here is my catch and finally block
catch (Exception)
{
if (((txtisTlf.Text.Length) + (txtKod.Text.Length)) > 20 || ((txtCep.Text.Length) + (txtCepKod.Text.Length)) > 20 || ((txtEvKod.Text.Length) + (txtEvTlf.Text.Length)) > 20 ||(txtFax.Text.Length) > 20)

MessageBox.Show("İş Telefonu,Cep Telefonu,Ev Telefonu,Fax No Alanları 20 Karakterden Fazla Olamaz", "Uyarı", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
finally
{
con.Close();
}

Re: something wrong in codes

OriginalGriff31-Dec-09 4:39

OriginalGriff

31-Dec-09 4:39

Replace the "catch (Exception)" with "catch (Exception ex)" and have a look at the ex message and so forth. It will be telling you there is an error in your SQL syntax and will probably say "in SQL syntax near ..." where the ... bit gives you a clue where the problem is.
If that doesn't make is obvious, then cut down the insert statement until either it works or has only one value left - in which case the problem will be your connection string.

BTW: Parameters.Add(...).Value has been superceeded by Parameters.AddWithValue(name, value) - it won't make any difference at this point, but it's worth using the up-to-date stuff if you can.

All those who believe in psycho kinesis, raise my hand.

Re: something wrong in codes

Erdinc271-Jan-10 23:44

Erdinc27

1-Jan-10 23:44

hi man
again me
i wrote ex as u said before and i have such a warning as an exception...
"The parameterized(@ad nvarchar(6),@soyad nvarchar(6),@firma nvarchar(4000))insert" expects parameter @firma,which was not supplied.and i have such codes to add this datas

cmd.Parameters.AddWithValue("@ad", txtAd.Text);
cmd.Parameters.AddWithValue("@soyad", txtSoyad.Text);
cmd.Parameters.AddWithValue("@firma", cmbFirma.SelectedItem);

and i keep that areas in my database like that
ad nvarchar(50),
soyad nvarchar(50),
firma nvarchar(60)

so i didnt get the problem i have now Frown | :(

Re: something wrong in codes

OriginalGriff2-Jan-10 0:02

OriginalGriff

2-Jan-10 0:02

I take it that you mean you have a field in your DB called "firma" which is declared as "nvarchar(60)", but your insert statement is still not working, and complains that parameter "@firma" is not supplied?
In which case, I suspect that cmbFirma.SelectedItem is a ComboBox and you have not selected anything in it? In which case "cmbFirma.SelectedItem" will return null, and this may be your problem - breakpoint the insert and check.
Good luck (and happy new year)!

All those who believe in psycho kinesis, raise my hand.

Retrieve an image from another pc in network

wasifmuneer31-Dec-09 1:54

wasifmuneer

31-Dec-09 1:54

Dear Members,
kindly tell me the problem how to resolve it,i have to retrieve an image file from another network pc or remote pc,i m confused about it,how to work on it either have to work by mapping a network drive,or have a windows service for this purpose...any suggestion plzz

The language platform is C#

Regards

Re: Retrieve an image from another pc in network

Paul Unsworth31-Dec-09 2:06

Paul Unsworth

31-Dec-09 2:06

I'm confused by your question.

Am I right in saying that you want to copy a file from another location on the network to use it?

I would simply suggest mapping a drive to that location. That location would have to be shared though.

Then you just use <codefile.copy(sourcefilepath, destinationfilepath);=""> from System.IO;.

I hope this helps, or even makes sense. I need more coffee.... Big Grin | :-D

oooo, the Jedi's will feel this one....

Re: Retrieve an image from another pc in network

minnie mouse31-Dec-09 14:48

minnie mouse

31-Dec-09 14:48

Try having a look for " Socket Server C#" & " Socket Client C#"
or you could use good old "Sneakernet". ????
This is a bad question.

problem with custom serialization in .net 2.0

prasadbuddhika31-Dec-09 1:48

prasadbuddhika

31-Dec-09 1:48

i'm trying to serialize and deserialize an object using xmlSerializer .the serialization part is ok ,but in the deserialization part i don't get "amount" calculated as expected.

following is the code of the object i serialize.

[Serializable]
public class _object
{
public int itemCnt;
public string itemName;
public decimal unitPrice;
[NonSerialized]public decimal amount;

public _object(int _itemCnt,string _itemName,decimal _unitPrice)
{
itemCnt = _itemCnt;
itemName = _itemName;
unitPrice = _unitPrice;
}

protected _object(SerializationInfo info, StreamingContext context)
{
itemCnt = info.GetInt32("itemCnt");
itemName = info.GetString("itemName");
unitPrice = info.GetDecimal("unitPrice");
amount = info.GetDecimal("total");
}

[SecurityPermissionAttribute(SecurityAction.Demand,SerializationFormatter = true)]
public virtual void GetObjectData(SerializationInfo info, StreamingContext context)
{
info.AddValue("itemCnt", itemCnt);
info.AddValue("itemName", itemName);
info.AddValue("unitPrice", unitPrice);
amount = itemCnt * unitPrice;
}

}

any idea why?

Re: problem with custom serialization in .net 2.0

Paul Unsworth31-Dec-09 2:00

Paul Unsworth

31-Dec-09 2:00

Are you setting the amount outside your class? I cannot see where it would be calculated.

prasadbuddhika wrote:
[NonSerialized]public decimal amount;

If this is the case, when you are deserialzing your class, you will lose the Amount value as it is NonSerialized, so not stored when serialized... Poke tongue | ;-P

oooo, the Jedi's will feel this one....

Re: problem with custom serialization in .net 2.0

Abhinav S31-Dec-09 3:14

Abhinav S

31-Dec-09 3:14

prasadbuddhika wrote:
[NonSerialized]public decimal amount;

Amount is marked as 'non serializable'.

There are only 10 types of people in this world — those who understand binary, and those who don't.

Re: problem with custom serialization in .net 2.0

prasadbuddhika31-Dec-09 19:14

prasadbuddhika

31-Dec-09 19:14

wish you all a happy new year..! thanx for your reply . i had made a mistake the constructor with the serialzationinfo and the streamcontext is the one which will be called at deserialization. so i had to calculate the amount in this . then the constructor will be changed to

protected _object(SerializationInfo info, StreamingContext context)
        {
            itemCnt = info.GetInt32("itemCnt");
            itemName = info.GetString("itemName");
            unitPrice = info.GetDecimal("unitPrice");
            amount = itemCnt * unitPrice;
        }

but the problem is still remaining...the itemCnt,itemName and unitPrice are getting accurately , only the calculation is not taking place..

"The path is not of a legal form." on trying to start the service created in c#

sri_346431-Dec-09 0:25

sri_3464

31-Dec-09 0:25

Hi,

I tried created a windows service which does a file transfer from the folder its watching whenever a new file being created in it.I am getting an exception saying "The path is not of a legal form." on trying to start the service. An the path the exception refering to is the path that i set to the FileSystemWatch. Path property. I dont understand why it happens. The path is "D:\Test". The folder has all the permission to access.

Can anyone help me out.

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