PIndirectChannel Class Reference

#include <indchan.h>

Inheritance diagram for PIndirectChannel:

List of all members.

Public Member Functions
Overrides from class PObject
Comparison	Compare (const PObject &obj) const
Overrides from class PChannel
virtual PString	GetName () const
virtual BOOL	Close ()
virtual BOOL	IsOpen () const
virtual BOOL	Read (void *buf, PINDEX len)
virtual BOOL	Write (const void *buf, PINDEX len)
virtual BOOL	Shutdown (ShutdownValue option)
virtual PChannel *	GetBaseReadChannel () const
virtual PChannel *	GetBaseWriteChannel () const
virtual PString	GetErrorText (ErrorGroup group=NumErrorGroups) const
Channel establish functions
BOOL	Open (PChannel &channel)
BOOL	Open (PChannel *channel, BOOL autoDelete=TRUE)
BOOL	Open (PChannel *readChannel, PChannel *writeChannel, BOOL autoDeleteRead=TRUE, BOOL autoDeleteWrite=TRUE)
PChannel *	GetReadChannel () const
BOOL	SetReadChannel (PChannel *channel, BOOL autoDelete=TRUE)
PChannel *	GetWriteChannel () const
BOOL	SetWriteChannel (PChannel *channel, BOOL autoDelete=TRUE)
Protected Member Functions
virtual BOOL	OnOpen ()
Protected Attributes
PChannel *	readChannel
	Channel for read operations.
BOOL	readAutoDelete
	Automatically delete read channel on destruction.
PChannel *	writeChannel
	Channel for write operations.
BOOL	writeAutoDelete
	Automatically delete write channel on destruction.
PReadWriteMutex	channelPointerMutex
	Race condition prevention on closing channel.

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Detailed Description

This is a channel that operates indirectly through another channel(s). This allows for a protocol to operate through a "channel" mechanism and for its low level byte exchange (Read and Write) to operate via a completely different channel, eg TCP or Serial port etc.

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Constructor & Destructor Documentation

PIndirectChannel::PIndirectChannel

(

)

Create a new indirect channel without any channels to redirect to. If an attempt to read or write is made before Open() is called the the functions will assert.

PINLINE PIndirectChannel::~PIndirectChannel

(

)

Close the indirect channel, deleting read/write channels if desired.

PIndirectChannel::PIndirectChannel

(

)

Create a new indirect channel without any channels to redirect to. If an attempt to read or write is made before Open() is called the the functions will assert.

PINLINE PIndirectChannel::~PIndirectChannel

(

)

Close the indirect channel, deleting read/write channels if desired.

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Member Function Documentation

Comparison PIndirectChannel::Compare

(

const PObject &

obj

)

const [virtual]

Determine if the two objects refer to the same indirect channel. This actually compares the channel pointers.

Returns:

EqualTo if channel pointer identical.

Parameters:

obj	Another indirect channel to compare against.

Reimplemented from PChannel.

virtual PString PIndirectChannel::GetName

(

)

const [virtual]

Get the name of the channel. This is a combination of the channel pointers names (or simply the channel pointers name if the read and write channels are the same) or empty string if both null.

Returns:

string for the channel names.

Reimplemented from PChannel.

virtual BOOL PIndirectChannel::Close

(

)

[virtual]

Close the channel. This will detach itself from the read and write channels and delete both of them if they are auto delete.

Returns:

TRUE if the channel is closed.

Reimplemented from PChannel.

Reimplemented in PFTPClient, PSMTPClient, PPOP3Client, PRFC822Channel, and PSSLChannel.

virtual BOOL PIndirectChannel::IsOpen

(

)

const [virtual]

Determine if the channel is currently open and read and write operations can be executed on it. For example, in the PFile# class it returns if the file is currently open.

Returns:

TRUE if the channel is open.

Reimplemented from PChannel.

virtual BOOL PIndirectChannel::Read	(	void *	buf,
		PINDEX	len
	)			[virtual]

Low level read from the channel. This function may block until the requested number of characters were read or the read timeout was reached. The GetLastReadCount() function returns the actual number of bytes read.

This will use the readChannel# pointer to actually do the read. If readChannel# is null the this asserts.

The GetErrorCode() function should be consulted after Read() returns FALSE to determine what caused the failure.

Returns:

TRUE indicates that at least one character was read from the channel. FALSE means no bytes were read due to timeout or some other I/O error.

Parameters:

buf	Pointer to a block of memory to receive the read bytes.
len	Maximum number of bytes to read into the buffer.

Reimplemented from PChannel.

Reimplemented in PDelayChannel, PInternetProtocol, and PSSLChannel.

virtual BOOL PIndirectChannel::Write	(	const void *	buf,
		PINDEX	len
	)			[virtual]

Low level write to the channel. This function will block until the requested number of characters are written or the write timeout is reached. The GetLastWriteCount() function returns the actual number of bytes written.

This will use the writeChannel# pointer to actually do the write. If writeChannel# is null the this asserts.

The GetErrorCode() function should be consulted after Write() returns FALSE to determine what caused the failure.

Returns:

TRUE if at least len bytes were written to the channel.

Parameters:

buf	Pointer to a block of memory to write.
len	Number of bytes to write.

Reimplemented from PChannel.

Reimplemented in PDelayChannel, PRFC822Channel, PInternetProtocol, and PSSLChannel.

virtual BOOL PIndirectChannel::Shutdown

(

ShutdownValue

option

)

[virtual]

Close one or both of the data streams associated with a channel.

The behavour here is to pass the shutdown on to its read and write channels.

Returns:

TRUE if the shutdown was successfully performed.

Parameters:

option

Flag for shut down of read, write or both.

Reimplemented from PChannel.

Reimplemented in PSSLChannel.

virtual PChannel* PIndirectChannel::GetBaseReadChannel

(

)

const [virtual]

This function returns the eventual base channel for reading of a series of indirect channels provided by descendents of PIndirectChannel#.

The behaviour for this function is to return "this".

Returns:

Pointer to base I/O channel for the indirect channel.

Reimplemented from PChannel.

virtual PChannel* PIndirectChannel::GetBaseWriteChannel

(

)

const [virtual]

This function returns the eventual base channel for writing of a series of indirect channels provided by descendents of PIndirectChannel#.

The behaviour for this function is to return "this".

Returns:

Pointer to base I/O channel for the indirect channel.

Reimplemented from PChannel.

virtual PString PIndirectChannel::GetErrorText

(

ErrorGroup

group = NumErrorGroups

)

const [virtual]

Get error message description. Return a string indicating the error message that may be displayed to the user. The error for the last I/O operation in this object is used.

Returns:

Operating System error description string.

Parameters:

group

Error group to get

Reimplemented from PChannel.

Reimplemented in PSSLChannel.

BOOL PIndirectChannel::Open

(

PChannel &

channel

)

Set the channel for both read and write operations. This then checks that they are open and then calls the OnOpen() virtual function. If it in turn returns TRUE then the Open() function returns success.

Returns:

TRUE if both channels are set, open and OnOpen() returns TRUE.

Parameters:

channel

Channel to be used for both read and write operations.

BOOL PIndirectChannel::Open	(	PChannel *	channel,
		BOOL	autoDelete = TRUE
	)

Set the channel for both read and write operations. This then checks that they are open and then calls the OnOpen() virtual function. If it in turn returns TRUE then the Open() function returns success.

The channel pointed to by channel# may be automatically deleted when the PIndirectChannel is destroyed or a new subchannel opened.

Returns:

TRUE if both channels are set, open and OnOpen() returns TRUE.

Parameters:

channel	Channel to be used for both read and write operations.
autoDelete	Automatically delete the channel

BOOL PIndirectChannel::Open	(	PChannel *	readChannel,
		PChannel *	writeChannel,
		BOOL	autoDeleteRead = TRUE,
		BOOL	autoDeleteWrite = TRUE
	)

Set the channel for both read and write operations. This then checks that they are open and then calls the OnOpen() virtual function. If it in turn returns TRUE then the Open() function returns success.

The channels pointed to by readChannel# and writeChannel# may be automatically deleted when the PIndirectChannel is destroyed or a new subchannel opened.

Returns:

TRUE if both channels are set, open and OnOpen() returns TRUE.

Parameters:

readChannel	Channel to be used for both read operations.
writeChannel	Channel to be used for both write operations.
autoDeleteRead	Automatically delete the read channel
autoDeleteWrite	Automatically delete the write channel

PINLINE PChannel * PIndirectChannel::GetReadChannel

(

)

const

Get the channel used for read operations.

Returns:

pointer to the read channel.

BOOL PIndirectChannel::SetReadChannel	(	PChannel *	channel,
		BOOL	autoDelete = TRUE
	)

Set the channel for read operations.

Returns:

Returns TRUE if both channels are set and are both open.

Parameters:

channel	Channel to be used for both read operations.
autoDelete	Automatically delete the channel

PINLINE PChannel * PIndirectChannel::GetWriteChannel

(

)

const

Get the channel used for write operations.

Returns:

pointer to the write channel.

BOOL PIndirectChannel::SetWriteChannel	(	PChannel *	channel,
		BOOL	autoDelete = TRUE
	)

Set the channel for read operations.

Returns:

Returns TRUE if both channels are set and are both open.

Parameters:

channel	Channel to be used for both write operations.
autoDelete	Automatically delete the channel

virtual BOOL PIndirectChannel::OnOpen

(

)

[protected, virtual]

This callback is executed when the Open() function is called with open channels. It may be used by descendent channels to do any handshaking required by the protocol that channel embodies.

The default behaviour is to simply return TRUE.

Returns:

Returns TRUE if the protocol handshaking is successful.

Reimplemented in PFTPClient, PFTPServer, PSMTPClient, PSMTPServer, PPOP3Client, PPOP3Server, PRFC822Channel, and PSSLChannel.

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Member Data Documentation

PChannel* PIndirectChannel::readChannel [protected]

Channel for read operations.

BOOL PIndirectChannel::readAutoDelete [protected]

Automatically delete read channel on destruction.

PChannel* PIndirectChannel::writeChannel [protected]

Channel for write operations.

BOOL PIndirectChannel::writeAutoDelete [protected]

Automatically delete write channel on destruction.

PReadWriteMutex PIndirectChannel::channelPointerMutex [protected]

Race condition prevention on closing channel.

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The documentation for this class was generated from the following files:

• indchan.h
• osutil.inl

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