S60Ex\WebClient CONE 36 on exit

[nickager]

Hi,

I used the "S60Ex\WebClient" sample as the basis for some http code I'm adding to an application. Subsequently my application started generating "CONE 36" [Open handles were found during application shutdown] on exit in the emulator. I'm using S60_3rd_FP1 SDK. After sometime spent trying to isolate the cause of the error, I tested the WebClient sample and realised it was suffering from the same issue.

Googling the problem revealed: http://discussion.forum.nokia.com/fo...ad.php?t=76778.

As a result I modified my code to look like:

RHTTPSession iSession;
RHTTPTransaction iTransaction;
RSocketServ iSocketServ;
RConnection iConnection;
.
.
.
User::LeaveIfError(iSocketServ.Connect());
User::LeaveIfError(iConnection.Open(iSocketServ));
User::LeaveIfError(iConnection.Start());
iSession.OpenL();
RStringPool stringPool = iSession.StringPool();
RHTTPConnectionInfo connInfo = iSession.ConnectionInfo();
connInfo.SetPropertyL(stringPool.StringF(HTTP::EHttpSocketServ, RHTTPSession::GetTable()), THTTPHdrVal(iSocketServ.Handle()));
TInt connPtr = reinterpret_cast<TInt>(&iConnection); 
connInfo.SetPropertyL(stringPool.StringF(HTTP::EHttpSocketConnection, RHTTPSession::GetTable()), THTTPHdrVal(connPtr));
.
.
.
iTransaction.SubmitL();
.
.
.
iTransaction.Close();
iSession.Close();
iConnection.Close();
iSocketServ.Close();

Is this the cononical way to create an HTTP session? If so is there any decent documentation describing this mad mess of code?
I've noticed that iConnection.Start() blocks for a couple of seconds. Any idea why? I could convert to the asynchronous form, but I'd like to know if there is a way to reduce the delay.

Can someone from Symbian/Nokia make sure the WebClient sample is "CONE 36" free and save future developers potential confusion.

Thanks in advance

Nick

[vasant21]

RConnection with Http Client API is generally used to provide the connection preferences, now as far as cone 36 error is concerned, first try it on real device i think it should work fine.

[KarstenBln]

Hello Nick,

I had a similar problem. The webclient example compiled and run fine in the emulator. (There was just a problem that cbsserver crashes always when the emulators comes up. But that's not related to the webclient and it only happens when I'm working as normal user while the SDK was installed by an administrator account).

I changed the program because I didn't want to type the long url every time I start the application, I defined a resource for the url string, added a new menu entry beside the "enter url" and copied the function where the dialog to enter the url is called. I deleted this part in the copy and replaced it by just reading the url from the resource.

Well, when I use the webclient in the emulator and use the enter url function everything runs fine. But when I use the existing url function and end the webclient then the CONE 36 is shown.

There was nothing changed related to creating or using the http session. Isn't it crazy?

Karsten

[nickager]

hello vasant21
Yes WebClient works on the device and on the emulator, but generates CONE 36 on exit on the emulator. I'm working under the assumption that this is because the emulator displays panics whereas on the device applications fail silently, From the emulator documentation:

When a thread is panicked, the debugger provides comprehensive information about the panic

Therefore an absence of an error message when testing an application on the device wouldn't necessarily mean that error is non-existant and can therefore be ignored. Is there some floor in my understanding?

[wizard_hu_]

You can get the message on the target device too: http://www.forum.nokia.com/document/...r_messages.htm (ErrRd also makes the panic-box displayed on devices where it is disabled by default)

[nickager]

Hi Karsten,

Thanks for the reply. I think you might be onto something as the CONE error messages state that CONE panics are:

User Interface Control Framework panics

why then would my and your modified code not report the panic? Is there any way to understand more about the underlying cause of a panic? Bizarre.
I'll do some more digging and post if I come to a conclusion.

[nickager]

Hi wizard_hu,

Thanks for the link. I've downloaded "Errrd" and verified that the panic-box is now being displayed on my N95 by manually causing a panic in a test application. However I don't see the panic from WebClient on the device that I see on the emulator. Could this be a spurious emulator error? Any thoughts?

[_ile]

Hi,

Can someone from Symbian/Nokia make sure the WebClient sample is "CONE 36" free and save future developers potential confusion.

Thanks in advance

Nick

Yep, WebClient example will be "CONE 36"-free in 3rd FP2 SDK.

-- ile

[nickager]

Hi ile,

Yep, WebClient example will be "CONE 36"-free in 3rd FP2 SDK

So is the problem with the WebClient example code, or is it a bug in the SDK? In other words, does the WebClient code represent a bug free example of HTTP download, or is there some other example I should study?

Thanks in advance

Nick

[_ile]

Hi ile,


So is the problem with the WebClient example code, or is it a bug in the SDK? In other words, does the WebClient code represent a bug free example of HTTP download, or is there some other example I should study?

Thanks in advance

Nick

The problem is not strictly speaking in WebClient-code; instead, RHttpTransaction appears to leave some handles open. WebClient will be modified in the same fashion as instructed in mentioned thread: http://discussion.forum.nokia.com/fo...ad.php?t=76778

I'd think that also Forum Nokia's HTTP Client API example has the same workaround implemented.

(Whether that RHttpTransaction-issue should be considered as a bug in Symbian or "undocumented behaviour", is a matter of discussion... ;)

-- ile

[nickager]

Good to know the WebClient example will be fixed/have a workaround added!