--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/devsound/a3facf/inc/maudiocontextobserver.h	Tue Feb 02 01:56:55 2010 +0200
@@ -0,0 +1,97 @@
+/*
+* Copyright (c) 2006-2009 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:
+*
+*/
+
+
+
+
+/**
+ @file
+ @publishedPartner 
+ @released
+*/
+
+#ifndef MAUDIOCONTEXTOBSERVER_H
+#define MAUDIOCONTEXTOBSERVER_H
+
+#include <a3f/a3fbase.h>
+
+const TUid KUidA3FContextCommitUpdate		= {0x1028343E};
+const TUid KUidA3FContextPreEmptedCommit	= {0x1028343F};
+const TUid KUidA3FContextPreEmption			= {0x10283440};
+const TUid KUidA3FContextPreEmptionUpdate	= {0x10283441};
+const TUid KUidA3FContextUpdateComplete		= {0x10283442};
+const TUid KUidA3FContextAbort				= {0x10283443};
+
+/**
+ * KUidA3FContextCommitUpdate - Follows a Commit() call. Signals that Commit() has been successfully received by MMRC 
+ * and that update callbacks are about to follow.  Note will still be called if MMRC rejects the request for policy reasons 
+ * – in which case, the callbacks will show the original value. 
+ *if aError is not KErrNone, then the implementation tried to apply the change but this failed 
+ * so that the implementation is “rolled-back” to the previous. However, KErrAbort says that this roll-back failed, 
+ * and streams have been placed in a Dead state.
+ *
+ * KUidA3FContextPreEmptedCommit -  Follows a Commit() call, but signals that that MMRC is doing a simultaneous pre-emption. 
+ * Update callbacks are about to follow, but these relate to the pre-emption. The original request is lost.
+ * An error of KErrAbort says that the change MMRC requested failed, and typically streams are placed in a “Dead” mode.
+ *
+ * KUidA3FContextPreEmption -  Initial indication to the client that it is to be pre-empted. 
+ * The client should treat the Context and its Components as “locked” – see below. 
+ *
+ * KUidA3FContextPreEmptionUpdate - Will follow a KUidA3FContextPreEmption and indicates that callbacks 
+ * are about to start to indicate the update. An error of KErrAbort says that the change MMRC requested failed, 
+ * and typically streams are placed in a “Dead” mode.
+ * 
+ * KUidA3FContextUpdateComplete - Signals that all callbacks are complete – Commit() can be called again, if required.
+ *
+ * KUidA3FContextAbort - Error occurred due to the commit or pre-emption cycle itself – 
+ * that is something to do with the associated message passing mechanism etc. 
+ * this terminates the whole cycle, whatever the current state. It should leave the context in a “reasonable state” 
+ *– usually the original state.  aError gives the associated reason for this.
+ */
+
+/*
+ * Following Commit() or ContextEvent(KUidA3FContextPreEmption), the associated Context should be considered “locked” 
+ * until the receipt of events KUidA3FContextCommitUpdate, KUidA3FContextPreEmptedCommit or KUidA3FContextPreEmptionUpdate. 
+ * By locked it is meant that no changes shall be requested by the Client from the Context nor its associated Components, 
+ * nor Commit() called.
+ *
+ * Following events KUidA3FContextCommitUpdate, KUidA3FContextPreEmptedCommit or KUidA3FContextPreEmptionUpdate, 
+ * the Client can be requested changes to the Context and associated Components, but Commit() cannot be called.
+ * 
+ * Following event KUidA3FContextUpdateComplete Commit() can be called.
+ *
+ * Following the receipt of event KUidA3FContextPreEmptedCommit or KUidA3FPreEmptionUpdate, 
+ * any pending requested changes to the Context or its Components are lost – there is an implied call to MAudioContext::Reset(). 
+ */
+
+
+/**
+ * Defines the interface for observing context states.
+ */
+class MAudioContextObserver
+	{
+public:
+	/**
+	 * Callback to context observer to show progression through Commit() and pre-emption cycles.
+	 *
+	 * @param a Uid giving the specific event.
+	 * @param  an error code. KErrNone if successful, otherwise one of the system wide error codes.
+	*/
+	virtual void ContextEvent(TUid aEvent, TInt aError)=0;
+	};
+
+#endif // MAUDIOCONTEXTOBSERVER_H