Wiley.Developing.Software.for.Symbian.OS.2nd.Edition.Dec.2007 (779887), страница 68
Текст из файла (страница 68)
In response to this, the Connect() is performed onthe socket to hook it to the rainmaker.wunderground.com server atport address 3000 and the state changes to EConnecting.Upon the Connect() completion, RunL() is called again, invokingthe RSocket Send() method to send the city code. The state is changedto ESending.Once the Send() completes, the RunL() calls RecvOneOrMore()to start getting the weather data. The state changes to EReceivingand remains in this state as long as the data keeps coming from theserver (although, in this case, you will probably get all the data onthe first call). RunL() looks for the end of the lines of ‘=’ characters352SYMBIAN OS TCP/IP NETWORK PROGRAMMINGRHostResolver::GetByName()EResolvingNameRSocket::Connect()EConnectingRSocket::Send()ESendingRSocket::RecvOneOrMore()EReceivingContinuecollecting dataCallback throughMWeatherObserver::TemperatureReport()orMWeatherObserver::TemperatureError()Figure 11.4 Weather Example State Machine(see Figure 11.3), which immediately precede the temperature.
Oncethe temperature is found, it calls the TemperatureReport() functionof the MWeatherObserver class passed in on the NewL() (stored iniObserver), passing it the city code and the temperature. If an erroroccurs at any time, the method CWeatherInfo::Cleanup() is called,which is implemented as follows:void CWeatherInfo::Cleanup(TInt aError){iSocket.Close();iSocketSrv.Close();iResolver.Close();TBuf<50> errStr;if (aError!=KErrNone){switch (iCommState){case EInitializing:{EXAMPLE: RETRIEVING WEATHER INFORMATION353_LIT(KErrStr,"Error initializing communications");errStr.Copy(KErrStr);break;}case EResolvingName:{_LIT(KErrStr,"Error resolving name");errStr.Copy(KErrStr);break;}case EConnecting:{_LIT(KErrStr,"Error connecting to server");errStr.Copy(KErrStr);break;}case ESending:{_LIT(KErrStr,"Error sending request");errStr.Copy(KErrStr);break;}case EReceiving:{_LIT(KErrStr,"Error receiving data");errStr.Copy(KErrStr);break;}default:{_LIT(KErrStr,"Unknown error");errStr.Copy(KErrStr);break;}}iObserver.TemperatureError(errStr,aError);}}Cleanup() closes all the network objects (it does not hurt to callClose() on a handle that is not yet open), and creates an error message based on what the state stored in iCommState is at the timeof the error.
It then invokes the observer’s TemperatureError()callback function, passing it the error message along with the errorcode.11.4.2Adding this Code to SimpleExThe full sample code for adding the functionality described above tothe S60 and UIQ versions of SimpleEx is available from the websitefor this book, which can be found on the Symbian Developer Networkwiki (http://developer.symbian.com/wiki). Here are the basic steps I354SYMBIAN OS TCP/IP NETWORK PROGRAMMINGperformed to integrate this functionality in SimpleEx:1.I added a new menu item called ‘Get temperature’ to the resourcefile, changing the menu definition for S60 and the commandresource for UIQ. I named the command ESimpleExTemperatureCommand.2.I added the ESimpleExTemperatureCommand to the commandenum in the program’s simpleEx.hrh file.3.For S60, I added the MWeatherObserver interface to CSimpleExAppUI in the class definition using multiple inheritance andadded to the class the two virtual functions of MWeatherObserverthat must be overridden:class CSimpleExAppUi : public CAknAppUi, public MWeatherObserver{...// from MWeatherObservervirtual void TemperatureReport(TDesC& aCity,TDesC& aTemperature);virtual void TemperatureError(TDesC& aErrorStr,TInt aErrCode);...};For UIQ, I added this interface to CSimpleExAppView instead ofCSimpleExAppUi (I wanted it where the application UI handlerresides).4.I added a private member variable, CWeatherInfo *iWeather,to the CSimpleExAppUI class in the case of S60, and to theCSimpleExAppView class in the case of UIQ.5.I included the previously listed example source (either in separatefiles or in the existing source and include files).6.In the CSimpleExAppUi::ConstructL() (CSimpleExAppView::ConstructL() for UIQ) I added the statement:iWeather = CWeatherInfo::NewL(*this);to create the example’s active object.7.In the CSimpleExAppUi destructor I added:delete iWeather;8.In the CSimpleExAppUi::HandleCommandL() (CSimpleExAppView::HandleCommandL() for UIQ), I added a case forthe command ESimpleExTemperatureCommand, which looksEXAMPLE: RETRIEVING WEATHER INFORMATION355as follows:case ESimpleExTemperatureCommand:{// Display the temperature in Austin, TX_LIT(KCityCode,"AUS");iWeather->GetTemperature(KCityCode);}9.I overrode the callback functions of the MWeatherObserver asfollows:void CSimpleExAppUi::TemperatureReport(TDesC& aCity,TDesC& aTemp){TBuf<50> str;_LIT(KTempTitle,"Report:");_LIT(KTempMessage,"Temperature in %S is %S");str.Format(KTempMessage,&aCity,&aTemp);TRAPD(res,iEikonEnv->InfoWinL(KTempTitle,str));}void CSimpleExAppUi::TemperatureError(TDesC& aErrStr,TInt aErrCode){TBuf<50> str;_LIT(KErrTitle,"Error:");_LIT(KErrMsg,"%S (%d)");str.Format(KErrMsg,&aErrStr,aErrCode);TRAPD(res, iEikonEnv->InfoWinL(KErrTitle, str));}Again, I did this in CSimpleExAppView class for the UIQ version.10.In the MMP file, I added insock.lib and esock.lib to theLIBRARY line, to include the libraries which implement the socketcalls.
I also added the line CAPABILITY NetworkServices,since, as I mentioned previously, the application requires thatcapability to communicate on the network. If you do not have thiscapability, the network API calls will fail.Build and run the updated SimpleEx program on the phone (Chapter 2shows how to use makesis to create a SIS file to enable you to installand run SimpleEx on the phone). When you select the ’Get temperature’ menu option, a network connection will be established. Once thecommunication is complete, the temperature of the city you requested (inthis case it is hardcoded to AUS, but you could modify to have the userenter it) is displayed on the screen.
Figure 11.5 shows the output of thisexample on an S60 device.Since the example uses an active object, you’ll note that the GUI is stillresponsive while the communication is taking place. For example, theStart menu item can be selected during the network communication356SYMBIAN OS TCP/IP NETWORK PROGRAMMINGFigure 11.5 Weather Example Screenand it will still display its dialog boxes. So, in effect, the entire networksequence to collect the weather information is running in the background.11.5Making a Network ConnectionUp to this point, we have not discussed how the network connectionsthemselves are represented and brought up, and we just relied on theoperating system to select the connection for us implicitly (while in manycases it will prompt the user for a connection) in our examples. Thissection will give a very brief overview of connections in Symbian OS.You should consult the SDK documentation for more details.On a Symbian OS smartphone, network connections are representedby Internet Access Points (IAPs).
IAPs can be created from the phone’scontrol panel, usually during initial setup. The information in an IAPincludes the physical connection type (such as GPRS or CSD), and thespecific attributes applicable to the selected connection type (such asthe phone number; user’s identifier and password for a dialup server,for CSD-type connections; or APN for a GPRS connection). You assign aname to the IAP when creating it, and that name is used when establishingthe connection.For example, you can create an IAP called T-Mobile GPRS to use theAPN provided by T-Mobile (e.g., Internet2.voicestream.com or general.t-mobile.co.uk).
Then, when you are prompted for a connection by thephone, you select T-Mobile GPRS to use the GPRS connection.Note that IAP setup varies from phone to phone, and also depends onthe particular service you intend to access. In many cases the IAP creationis done automatically for you (e.g., via your SIM or through a service SMSmessage).MAKING A NETWORK CONNECTION35711.5.1 Establishing a Connection for a ProgramThe example Symbian OS socket code, presented in section 11.3, createdand used a socket as if the smartphone connection was already established. In fact, this is often done in Symbian OS and is known as animplicit connection.
![](https://s.studizba.com/z.php?f=/templates/si/i/noavatar.png&w=100&h=100&t=1"){kind=avatar}
