C / C++ / MFC Discussion Boards

22-Mar-02 6:41

Please read the following sample code:

In CTestDlg....

BOOL CTestDlg::OnInitDialog()
{
CDialog::OnInitDialog();
.
.
.
// TODO: Add extra initialization here
mp_Server = (CServer*)
AfxBeginThread(RUNTIME_CLASS(CServer), THREAD_PRIORITY_NORMAL,
0, CREATE_SUSPENDED);
mp_Server->ResumeThread();

return TRUE; // return TRUE unless you set the focus to a control
}

void CTestDlg::OnOK()
{
// TODO: Add extra validation here
char buff[1024];
strcpy(buff, "This is a test of Simple Socket");
CSocket Client;
Client.Create();
Client.Connect("127.0.0.1",5001);
Client.Send(buff,strlen(buff));
}

In CServer.....

int CServer::Run()
{
// TODO: Add you specialized code here and/or call the base class

char buff[1024];

strcpy(buff, "This is the look before receive the socket");
CSocket socket;

if ( svrSocket.Accept(socket))
AfxMessageBox("Socket is created Succesfully");

socket.Receive(buff,sizeof(buff))
AfxMessageBox((CString)buff);

return 0;
}

This is a sample code for CSocket (posted by my professor in university). But I don't quite understand how CSocket works. When I execute the program, a dialog pop up, and a message box "This is the look before receive the socket" pop up. When I click OK button, it will pop up "Socket is created Successfully" and then "This is a test of Simple Socket".

However, when I click the OK button one more time, there is no response!!! I can put a AfxMessageBox() in OnOK(), and I found that there is execution in OnOK() at that time (messagebox pop up). Why Run() doesn't do anything as I did send the socket to there.....

Please help!!!!

Re: Need help about CSocket

Andres Manggini22-Mar-02 7:17

Andres Manggini

22-Mar-02 7:17

It's difficult to say without the full source code, but could it be that the thread has terminated, so it can not respond to the "Connect..." ?
in other words, once the run exits, the thread disappear, and there is no more server Smile | :)

.
this line:

if ( svrSocket.Accept(socket))

is probably blocking your thread waiting for a connection, thats the reason it only works once.

Andres Manggini.
Buenos Aires - Argentina.

Re: Need help about CSocket

22-Mar-02 7:32

Thanks for your reply!!

So, if i add a loop to contain "if ( svrSocket.Accept(socket))", then i can ask Run() to keep checking if there is more socket arrived.......is that right?

Also, how the parameter in this function "Client.Connect("127.0.0.1",5001);" come from?

ONe more question, can the Run() in CServer can block the process in OnOK() after Run() receives a socket from OnOK(). For example, OnOK() sends a socket to Run() and "if ( svrSocket.Accept(socket))" receives it. Because how some information from this socket(or packet), Run() has to block (or pause) the process in OnOK()....can it do happen?

Re: Need help about CSocket

Andres Manggini22-Mar-02 7:45

Andres Manggini

22-Mar-02 7:45

ChiYung wrote:
So, if i add a loop to contain "if ( svrSocket.Accept(socket))", then i can ask Run() to keep checking if there is more socket arrived.......is that right?

Yes, that's correct.

ChiYung wrote:
Also, how the parameter in this function "Client.Connect("127.0.0.1",5001);" come from?

first string is the IP Address, since the computer is connecting to itself, it's using 127.0.0.1 which is the same as localhost (or THIS computer Smile | :)

ChiYung wrote:
ONe more question, can the Run() in CServer can block the process in OnOK() after Run() receives a socket from OnOK(). For example, OnOK() sends a socket to Run() and "if ( svrSocket.Accept(socket))" receives it. Because how some information from this socket(or packet), Run() has to block (or pause) the process in OnOK()....can it do happen?

I am not quite sure to understand the question, but i'll tell you this, if
CServer is running on a different thread it shouldn't block OnOK(), but, OnOK will be blocked cause of :

CSocket Client;
Client.Create();
Client.Connect("127.0.0.1",5001);
Client.Send(buff,strlen(buff));

So, OnOK will be blocked until Client.Send(..) returns.

Hope this clarifies a bit, if you have more questions, post them here.

Andres Manggini.
Buenos Aires - Argentina.

Re: Need help about CSocket

22-Mar-02 7:56

THANK YOU VERY MUCH!!!!! YOU GAVE ME LOTS OF HINTS!!!!

Andres Manggini wrote:
I am not quite sure to understand the question, but i'll tell you this, if
CServer is running on a different thread it shouldn't block OnOK(), but, OnOK will be blocked cause of :

CSocket Client;
Client.Create();
Client.Connect("127.0.0.1",5001);
Client.Send(buff,strlen(buff));

So, OnOK will be blocked until Client.Send(..) returns.

Ok....how can i prevent Client.Send(..) returns..... is it suspend the thread of Run()...or......

Maybe I give you more detail....

I need to implement a DBMS program that simulate the Lock management. I use socket in CServer to implement the scheduler that handle the lock. It is one thread...... then there are hundreds of users to "access" the database object, so there are hundreds of threads. Each threads(uses) requires to get a lock permit from scheduler (CServer) in order to "access' the DB Object. This is what i'm going to do.

Why I need to block some process, because for example, thread A is trying to access the DB Object X, while thread B is reading something in Object X. Scheduler (CServer) requires to "block" thread A until thread B finished. At this time, thread A will be put in "waitqueue" (this is another issue).

Re: Need help about CSocket

Andres Manggini22-Mar-02 8:14

Andres Manggini

22-Mar-02 8:14

ChiYung wrote:
THANK YOU VERY MUCH!!!!! YOU GAVE ME LOTS OF HINTS!!!!

Great Smile | :)

.

ChiYung wrote:
Ok....how can i prevent Client.Send(..) returns..... is it suspend the thread of Run()...or......

Do you mean prevent Client.Send even after all the data has been sent ?
Cause, if you just want to prevent the return UNTIL all the data has been sent, that's already how it works, so don't have to do anything.

Andres Manggini.
Buenos Aires - Argentina.

Re: Need help about CSocket

22-Mar-02 8:30

Andres Manggini wrote:
Do you mean prevent Client.Send even after all the data has been sent ?
Cause, if you just want to prevent the return UNTIL all the data has been sent, that's already how it works, so don't have to do anything

I think I want the CServer to....let say suspend awhile (e.g. 20s) before the OnOK() receives the return signal from Client.Send()...........(it can make the OnOK() to suspend 20s too....right?

Sorry...I know I'm stupid.....;P Poke tongue | ;-P

Re: Need help about CSocket

Andres Manggini22-Mar-02 8:55

Andres Manggini

22-Mar-02 8:55

I don't know of you can do that just with the CSocket methods, i guess you'll have to implement a form on synchronization between the server and the clients..

maybe using socket as well, set up a small protocol between server and client to communicate (protocol as defined messages sent to each other)
not sure this is the solution for you here..

And.. you're no stupid, far from it Smile | :)

.

Regards,

Andres Manggini.
Buenos Aires - Argentina.

Re: Need help about CSocket

Nish Nishant22-Mar-02 8:29

Nish Nishant

22-Mar-02 8:29

To avoid blocking sockets you might want to use CAsyncSocket in place of CSocket.

Nish

One Nish is trouble enough.
Imagine 16 of me, dancing wild...
:jig::jig::jig::jig:
:jig::jig::jig::jig:
:jig::jig::jig::jig:
:jig::jig::jig::jig:

Coloured Buttons

joeperris22-Mar-02 6:27

joeperris

22-Mar-02 6:27

Anyone know how I can take a dialog box with 3 buttons that have no function at all and change the background colours of 2 of them to red and one gray??

Thanks.

Re: Coloured Buttons

Tim Deveaux22-Mar-02 6:30

Tim Deveaux

22-Mar-02 6:30

Try adding an OnCtlColor (if MFC) handler to the dialog and returning a brush of the desired color based on the control IDs...

Re: Coloured Buttons

joeperris22-Mar-02 6:34

joeperris

22-Mar-02 6:34

I'm not that experienced in visual c++ programming.. could you please tell me the syntax of how to write all that?

Thanks

Re: Coloured Buttons

Nish Nishant22-Mar-02 6:40

Nish Nishant

22-Mar-02 6:40

Or you could try using CButtonST v3.4

http://www.codeproject.com/buttonctrl/cbuttonst.asp

Nish

One Nish is trouble enough.
Imagine 16 of me, dancing wild...
:jig::jig::jig::jig:
:jig::jig::jig::jig:
:jig::jig::jig::jig:
:jig::jig::jig::jig:

Re: Coloured Buttons

Tim Deveaux22-Mar-02 7:17

Tim Deveaux

22-Mar-02 7:17

Actually, I was asleep at the switch in that reply - but if you search the articles here for 'owner draw' you'll get lots of info on what can be done.

Re: Coloured Buttons

Nish Nishant22-Mar-02 8:32

Nish Nishant

22-Mar-02 8:32

Tim Deveaux wrote:
Actually, I was asleep at the switch in that reply

Still feelin sheepish abt that eh, Tim?

Smile | :)

Nish

One Nish is trouble enough.
Imagine 16 of me, dancing wild...
:jig::jig::jig::jig:
:jig::jig::jig::jig:
:jig::jig::jig::jig:
:jig::jig::jig::jig:

Re: Coloured Buttons

Tim Deveaux22-Mar-02 9:40

Tim Deveaux

22-Mar-02 9:40

Ruined my whole day Frown | :(

Now, about this '16 Nish' concept... Confused | :confused:

Re: Coloured Buttons

Nish Nishant22-Mar-02 6:35

Nish Nishant

22-Mar-02 6:35

This wont work for buttons anymore...

Nish

One Nish is trouble enough.
Imagine 16 of me, dancing wild...
:jig::jig::jig::jig:
:jig::jig::jig::jig:
:jig::jig::jig::jig:
:jig::jig::jig::jig:

Re: Coloured Buttons

Tim Deveaux22-Mar-02 6:54

Tim Deveaux

22-Mar-02 6:54

Yes - I goofed - need to have an owner draw button...

Re: Coloured Buttons

Nish Nishant22-Mar-02 6:32

Nish Nishant

22-Mar-02 6:32

You can use a CBitmapButton

Nish

One Nish is trouble enough.
Imagine 16 of me, dancing wild...
:jig::jig::jig::jig:
:jig::jig::jig::jig:
:jig::jig::jig::jig:
:jig::jig::jig::jig:

Re: Coloured Buttons

joeperris22-Mar-02 6:37

joeperris

22-Mar-02 6:37

how would i do that?

custom preprocessor

22-Mar-02 5:04

hi,
I want to execute different functions depending on the condition set.I know it can be done with function pointers but I want to do it with preprocessors.
How to get about with it.
Cheers.

Re: custom preprocessor

Joaquín M López Muñoz22-Mar-02 5:34

Joaquín M López Muñoz

22-Mar-02 5:34

The standard approach is like this:

#ifdef SCENARIO1
f1(...);
#elif SCENARIO2
f2(...);
...
#else /* SCENARION */
fn(...);
#endif

Then in Project->Settings->C/C++->Preprocessor definitons set the appropriate macro depending on the scenario/configuration you wish to select.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

Re: custom preprocessor

23-Mar-02 2:30

hi,
ok but how to eneble those?
Gerrard

edit default

22-Mar-02 5:03

hi
i would like to add a default value of '1' in one of my edit box's when the program is executed.
Help on the code and where to place the code in the main would be good thanks

Poke tongue | ;-P

Re: edit default

Mazdak22-Mar-02 5:09

Mazdak

22-Mar-02 5:09

If your edit box is in a dialog OnInitDialog()

editbox.SetWindowText("1");

Mazy

"So,so you think you can tell,
Heaven from Hell,
Blue skies from pain,...
How I wish,how I wish you were here."
Wish You Were Here-Pink Floyd-1975

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