Sharing a File or Data

This section explains how to share a file using the Application Interworking (AIW) Service Handler API.

Context

The AIW Service Handler API listens to NFC connections and provides data to the callback method.

The NFC AIW API provides the following callbacks via MAiwNotifyCallback::HandleNotifyL():

NFC power on: This callback is called with the KAiwCmdNFCGive command and the KAiwEventStarted event identifier. The event parameter contains one parameter with the semantic id KNfcSemanticIdNfcPowerInfo and value KNfcPowerOn.
NFC sharing started: This callback is called when NFC connection hand over is complete and Bluetooth bearer connection is up. It is called with theKAiwCmdNFCGive command and the KAiwEventStarted event identifier, the event parameter list is empty. The application is then expected to provide the item(s) currently in focus to the NFC AIW provider. RFile or RArray types are supported and need to be stored into the AiwGenericParamList& aInParamList parameter of the ExecuteServiceCmdL method.

Error callback: This callback is called in case of error. This callback is called with the KAiwCmdNFCGive command and the KAiwEventStarted event identifier. The event parameter contains one parameter with semantic id KNfcSemanticIdNfcPowerInfo and error value.

Error Values	Description
KErrHardwareNotAvailable	NFC feature is not available or turned OFF by user. Sharing is not possible. The client application should instruct the user to turn the NFC ON.
KErrAbort	Bluetooth could not be enabled in offline mode. Sharing is not possible.
System wide error values	Error occurred during transfer or during prepare phase. Call `Reset()` and retry with the new prepare call.

Note: Errors related to KAiwCmdNFCEasySetup command is called back with KAiwEventError and empty parameter list.

NFC sharing completed: The HandleNotifyL() callback is called after the file is sent and the NFC transfer is completed. It is called with the KAiwCmdNFCGive command and the KAiwEventCompleted event identifier, the event parameter list is empty. The application can then send another file or if the transfer is completed it must release the connection by calling the Reset() method on CAiwServiceHandler object.

Prerequisites

Before you begin, refer to the following:

Sharing Enquiry

Steps

Define an AIW_INTEREST resource element in the resource file using KAiwCmdNFCGive as a service command and KAiwClassBase as a service class:

Example:

RESOURCE AIW_INTEREST r_example_app_aiw_nfc_interest
    {
    items =
        {
        AIW_CRITERIA_ITEM
            {
            id              = 200000;
            serviceCmd      = KAiwCmdNFCGive;
            contentType     = "*";
            serviceClass    = KAiwClassBase;
            maxProviders    = 1;
            }
        };
    }

Include aiwcommon.h and AiwServiceHandler.h header files in the application source files, and link to the servicehandler.lib library in the MMP file.

Call the ExecuteServiceCmdL method without providing AIW input parameters to initiate listening to NFC callbacks, as shown in the following code snippet:

Example:

iAiwServiceHandler = CAiwServiceHandler::NewL();
iAiwServiceHandler->AttachL( R_EXAMPLE_APP_AIW_NFC_INTEREST );
iAiwServiceHandler->ExecuteServiceCmdL( KAiwCmdNFCGive, 
                                        iAiwServiceHandler->InParamListL(),
                                        iAiwServiceHandler->OutParamListL(),
                                        KAiwOptASyncronous,
                                        this );

Implement MAiwNotifyCallback::HandleNotifyL() (declared in aiwcommon.h) to receive callback notifications, as shown in the following sample code snippet:

Example:

TInt CExampleApplication::HandleNotifyL(

	TInt aCmdId,
	TInt aEventId,
	CAiwGenericParamList& aEventParamList,
	const CAiwGenericParamList& /*aInParamList*/)
   {
   If ( aCmdId == KAiwCmdNFCGive )
       {
       if ( aEventId == KAiwEventStarted )
           {
 if( aEventParamList.Count() > 0 )
               {
               TAiwGenericParam param = aEventParamList[0];
               if ( param.SemanticId() == KNfcSemanticIdNfcPowerInfo ) 
                   {
                   if( param.Value() == KNfcPowerOn )
                       {
       	             // NFC is powered on and Bluetooth is enabled
                       }
                   }
     else
               { 
               // NFC connection detected, give in a RFile handle to the
               // file to be sent
               iInParamList = CAiwGenericParamList::NewL();
               TAiwGenericParam obj( EGenericParamFile,
                   TAiwVariant( iRFile ) );
               iInParamList->AppendL( obj );

               // Send the file via NFC (asynchronous)
               iAiwServiceHandler->ExecuteServiceCmdL( KAiwCmdNFCGive,
                   *iInParamList, iAiwServiceHandler->OutParamListL(),
                   KAiwOptASyncronous, this );
               }
           }
       else if ( aEventId == KAiwEventCompleted )
           {
           // NFC transfer completed – release touch 
           iAiwServiceHandler->Reset();
           delete iInParamList;
           iInParamList = NULL;
           }
       else // KAiwEventError
           {
           // In case of transfer failure release must be done.
           // For preparation failure resetting is not necessary
           if( aEventParamList.Count() > 0 )
               {
               TAiwGenericParam param = aEventParamList[0];
               if ( param.SemanticId() == KNfcSemanticIdError )
                   {
                   if( param.Value() == KErrHardwareNotAvailable )
                       {
                       // NFC not enabled. Reset must be called                               
                       }
                   else if( param.Value() == KErrAbort )
                       {
	 // Bluetooth could not be enabled in offline mode.
 		 // 
                       } 
                   else
                       {
                	 // other error
                       }
                   }
               else
                   {
                   // unspecified
                   }
               }

           iAiwServiceHandler->Reset();

           delete iInParamList;
           iInParamList = NULL;
           }
       }

   return KErrNone;
   }

Results

The file or data is shared between the two devices.