/*

* Copyright (c) 2006-2007 Nokia Corporation and/or its subsidiary(-ies). 

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description:  Active class notifying metada and channel name changes to SongHistoryDb engine

*

*/

#ifndef CIRSONGHISTORYENGPUBSUB_H

#define CIRSONGHISTORYENGPUBSUB_H

#define KMAXLENGTH 250

#include <e32base.h>

#include <e32property.h>

class MIRSongHistoryEngPubSubNotifyHandler;

/**

* Listens to one specified Publish & Subscribe key, notifying the observer whenever that key is changed.

*/

NONSHARABLE_CLASS(CIRSongHistoryEngPubSub) : public CActive

    {

    public:

        /**

        * Static constructor.

        * @param    aObserver   The observer to be notified of the changes in the listened key.

        * @param    aCategory   The category of the key.

        * @param    aKey        The key to listen to.

        */

    static CIRSongHistoryEngPubSub* NewL( MIRSongHistoryEngPubSubNotifyHandler&

    		aPubSubObserver, const TUid& aCategory, TUint aKey ,

    		const RProperty::TType aPropertyType  );

        /**

        * Static constructor.

        * @param    aObserver   The observer to be notified of the changes in the listened key.

        * @param    aCategory   The category of the key.

        * @param    aKey        The key to listen to.

        */

    static CIRSongHistoryEngPubSub* NewLC( MIRSongHistoryEngPubSubNotifyHandler&

    		aPubSubObserver, const TUid& aCategory, TUint aKey ,

    		const RProperty::TType aPropertyType  );

        /**

        * Destructor.

        */

        ~CIRSongHistoryEngPubSub();

    protected: // From CActive

        /**

    *void RunL()

    *The function is called by the active scheduler

    *when a request completion event occurs,

        */

        void RunL();

        /**

    *void DoCancel()

    *Invoked when the active object is cancelled.

        */

        void DoCancel();

    private:

        /**

        * Constructor.

        * @param    aObserver   The observer to be notified of the changes in the listened key.

        * @param    aCategory   The category of the key.

        * @param    aKey        The key to listen to.

        */

    CIRSongHistoryEngPubSub( MIRSongHistoryEngPubSubNotifyHandler& aPubSubObserver,

    	const TUid& aCategory, TUint aKey, const RProperty::TType aPropertyType );

        /**

        * Second-phase constructor.

        */

        void ConstructL();

    protected:

        /** Handle to the property. */

        RProperty iProperty;

        RProperty::TType iPropertyType;

        /** The observer to be notified of the changes in the listened key. */

        MIRSongHistoryEngPubSubNotifyHandler& iPubSubObserver;

        /** The category of the key to listen to. */

        TUid iCategory;

        /** The key to listen to. */

        TUint iKey;

        /** The cached value of the key. */

        mutable TBuf8<KMAXLENGTH> iText;

    };

#endif//IR_SONGHISTORYENGPUBSUB