Handling Callback Methods

Context

When an application is registered to listen to the LLCP-link status, CLlcpProvider calls the MLlcpLinkListener::LlcpRemoteFound() method when two NFC-enabled devices with LLCP support are placed together and the MLlcpLinkListener::LlcpRemoteLost() method when the devices are separated. When the MLlcpLinkListener::LlcpRemoteFound() method is called, the data transfer is possible between the local and the remote devices.

Steps

Create a connection-object between the local and remote devices to send the "Hello World!" ASCII text.

The following code snippet illustrates how the CMyOwnLlcpApplication::LlcpRemoteFound method is implemented:

// CMyOwnLlcpApplication::LlcpRemoteFound()
// From MLlcpLinkListener
// -----------------------------------------------------------------------------
//
void CMyOwnLlcpApplication::LlcpRemoteFound()
    {
    TInt error = KErrNone;
    MLlcpConnLessTransporter* conn = NULL;
    
    // Notify the UI.
    iLLcpEventUpdater->DrawLlcpRemoteFound();
    
    // Pointer of the MLlcpConnLessTransporter object is 
    // stored to the iLocalConnection member variables.
    if ( !iLocalConnection )
        {
        // Create the MLlcpConnLessTransporter object.
        TRAP( error, conn = iLlcp->CreateConnLessTransporterL( KInterestingSsap ) );
        
        if ( error == KErrNone )
            {
            // Create a connection wrapper to send data to the remote device. 
            TRAP( error, iLocalConnection = COwnLlcpConnection::NewL( conn ) );
            
            if ( error != KErrNone )
                {
                delete conn;
                }
            }
        }
    }
// -----------------------------------------------------------------------------
// End of CMyOwnLlcpApplication::LlcpRemoteFound()

Note: CLlcpProvider does not deallocate any memory block related to theMLlcpConnLessTransporter object. Clients can remove the MLlcpConnLessTransporter object at any time.

The following code snippet illustrates how the CMyOwnLlcpApplication::LlcpRemoteLost method is implemented. When this method is called, the data transfer between the local and the remote devices stops, and all existing MLlcpConnLessTransporter objects are removed.

// CMyOwnLlcpApplication::LlcpRemoteLost()
// From MLlcpLinkListener
// -----------------------------------------------------------------------------
//
void CMyOwnLlcpApplication::LlcpRemoteLost()
    {    
    Cleanup();
    
    // Notify the UI.
    iLLcpEventUpdater->DrawLlcpRemoteLost();
    }
// -----------------------------------------------------------------------------
// End of CMyOwnLlcpApplication::LlcpRemoteLost()