// 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:

//

#ifndef __MOUTPUTSTREAMOBSERVER_H__

#define __MOUTPUTSTREAMOBSERVER_H__

#include <e32std.h>

/**

The MOutputStream and MOutputStreamObserver classes provide the API to send

data to a connected remote host. They encapsulate the outbound stream of a 

connected socket. 

The output socket observer must bind itself to the output stream before using

any of the other MOutputStream functions. The MOutputStream::Bind() API is 

used to do this binding. When done for the first time the output stream moves

from the Idle state to the PendingSend state.

Once an observer has been bound to the output stream data can be sent to the

connected host using the MOutputStream::SendDataReq() API. This can only be 

done when the output stream is in the PendingSend state otherwise a panic 

occurs. The MOutputStream::SendDataReq() API changes the output stream state

to the SentData state. 

The supplied data buffer must remain valid until the observer is notified 

that the send has been successful. This is done using the 

MOutputStreamObserver::SendDataCnf() API. The output stream moves back to 

the PendingSend state.

The output stream can only be re-bound to another observer when in the 

PendingSend state. The re-binding does not change the state of the output

stream.

The MOutputSocket::Close() API closes the output stream synchronously. In 

this case the output stream observer will not be notified. Once the the call

completes the output stream is in the Closed state and is no longer valid. 

This synchronous close should be used when an asynchronous shutdown is not 

appropriate, e.g. when deleting the observer object in error conditions.

Similar to the asynchronous shutdown the corresponding input stream is also 

shutdown and its observer notified.

@see MOutputStream

@internalTechnology

@prototype

*/

class MOutputStreamObserver

	{

public:

	/**

	Confirms to the output stream observer that the data has been successfully

	sent to the remote host.

	@post		The output stream in the PendingSend state.

	*/

	virtual void SendDataCnf() =0;

	/**

	Indicates to the observer that the socket connection with the

	remote host has been closed. The output stream is no longer valid.

	@param 	aError  The error code explaining why the socket connection has

			closed. A value of KErrNone indicates that either the

			input or output stream observer requested that the 

			socket connection be closed.

	@post	The output stream is in the Closed state and is no longer valid.

	*/

	virtual void OutputStreamCloseInd(TInt aError) =0;

	};

#endif	// __MOUTPUTSTREAMOBSERVER_H__