Tutorial: Creating a Bluetooth service

Implementing start()

The start() implementation registers a SDP record using SerialPortSDPRecord.xml, starts the RFCOMM server for the service, and emits started() to tell Qt Extended whether the service started successfully or not:

    void BluetoothSerialPortExampleService::start()
    {
        if (!m_rfcommServer)
            m_rfcommServer = new QBluetoothRfcommServer(this);

        // Read the SDP record that we want to register for this service.
        QFile file(Qtopia::qtopiaDir() + "/etc/bluetooth/sdp/SerialPortSDPRecord.xml");
        if (!file.exists()) {
            emit started(true, tr("Cannot find SDP record file"));
            return;
        }
        if (!file.open(QIODevice::ReadOnly)) {
            emit started(true, tr("Error reading SDP record file"));
            return;
        }
        QBluetoothSdpRecord record = QBluetoothSdpRecord::fromDevice(&file);
        file.close();

        // QBluetoothAbstractService::registerRecord() registers a SDP record and
        // returns the service record handle for the newly registered service.
        m_sdpRecordHandle = registerRecord(record);
        if (m_sdpRecordHandle == 0) {
            emit started(true, tr("Error registering the SDP service"));
            return;
        }

        int rfcommChannel = QBluetoothSdpRecord::rfcommChannel(record);

        if (!startRfcommServer(rfcommChannel)) {
            // The server could not be started, so clean up and unregister the
            // SDP record using QBluetoothAbstractService::unregisterRecord().
            unregisterRecord(m_sdpRecordHandle);
            m_sdpRecordHandle = 0;

            emit started(true, tr("Error starting RFCOMM server"));
            return;
        }

        qDebug() << "Started example Bluetooth service";
        emit started(false, QString());
    }

Notice that started() must be emitted regardless of whether the service was started successfully or not.

Do not call start() from within your own code, because it is automatically invoked by the Bluetooth Service Manager when the service should be started. This could be because:

• The user has tried to start the service from within the Bluetooth settings application.
• The service has been created for the first time.
• The service was still running at the time of the last Qt Extended shutdown, in which case start() will automatically be invoked when the service is next created.

Note the path /etc/bluetooth/sdp/ is used when referencing SerialPortSDPRecord.xml. This is because that is the path specified by qbuild.pro for the installation of the XML file:

    # include the SDP record XML file
    # /etc/bluetooth/sdp is where other Qtopia SDP record XML files are located
    sdprecord.hint=image
    sdprecord.files=SerialPortSDPRecord.xml
    sdprecord.path=/etc/bluetooth/sdp

    void BluetoothSerialPortExampleService::stop()
    {
        if (m_rfcommServer) {
            m_rfcommServer->close();
            delete m_rfcommServer;
            m_rfcommServer = 0;
        }

        if (!unregisterRecord(m_sdpRecordHandle))
            qDebug() << "Error unregistering the SDP service";
        m_sdpRecordHandle = 0;

        qDebug() << "Stopped example Bluetooth service";
        emit stopped();
    }

    void BluetoothSerialPortExampleService::setSecurityOptions(QBluetooth::SecurityOptions options)
    {
        if (m_rfcommServer)
            m_rfcommServer->setSecurityOptions(options);
        m_securityOptions = options;
    }