/*

* Copyright (c) 2004 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:  Observer interface to receive presence change notifications.

*

*/

#ifndef __MPENGPRESENCEOBSERVER2_H

#define __MPENGPRESENCEOBSERVER2_H

//  INCLUDES

#include <E32Std.h>

//FORWARD DECLARATIONS

class CPEngPresenceNotifier2;

class CPEngTrackedPresenceIDs2;

// CLASS DECLARATION

/**

 * Observer interface to receive presence change notifications.

 * Observer is registered to CPEngPresenceNotifier2.

 *

 * With this API clients can

 * 1. Receive notifications from changes in cached

 *    presence attributes. Cached presence attributes

 *    are subscribed or fetched presence attributes

 *    stored to presence cache.

 *

 * 2. Receive notifications from user own attribute changes.

 *    Notification from user own attributes is requested with

 *    zero length PresenceID and they are also delivered with

 *    zero length PresenceID.

 *

 * @since 3.0

 */

class MPEngPresenceObserver2

    {

    public: //Observer methods

        /**

         * Presence change handler.

         *

         * Called by CPEngPresenceNotifier2 to handle presence

         * changed events. If this method leaves, error code is

         * reported back to HandlePresenceError().

         *

         * @since 3.0

         * @param aNotifier The notifier source where notification

         *        is coming from. No ownership transferred.

         * @param aChangedPresenceIDs The list of tracked Presence IDs.

         *        List contains both all tracked Presence IDs and changed

         *        Presence IDs. See CPEngTrackedPresenceIDs2 how to iterate

         *        through wanted Presence IDs. No ownership transferred.

         */

        virtual void HandlePresenceChangeL(

            CPEngPresenceNotifier2& aNotifier,

            CPEngTrackedPresenceIDs2& aChangedPresenceIDs ) = 0;

        /**

         * Notification failure handler.

         *

         * @since 3.0

         *

         * @param aError The error resulting from Presence Engine internal

         *        presence change event handling (e.g. out of memory) or

         *         leave error from HandlePresenceChangeL().

         * @param aNotifier The notifier of which event handling failed.

         *        No ownership transferred.

         */

        virtual void HandlePresenceError(

            TInt aError,

            CPEngPresenceNotifier2& aNotifier ) = 0;

    private: //Extensions

        /**

         * Reserved virtual table slots for future use.

         * Do not implement this.

         *

         * @since 3.0

         */

        virtual TInt PresenceObserverReserved() {

            return KErrNotSupported;

            }

    protected:  //Destructor

        /**

         * Protected destructor.

         * Observers can't be destroyed via this interface.

         */

        virtual ~MPEngPresenceObserver2() { }

    };

#endif //__MPENGPRESENCEOBSERVER2_H

// End of File