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 PBoolean	Close ()
virtual PBoolean	IsOpen () const
virtual PBoolean	Read (void *buf, PINDEX len)
virtual PBoolean	Write (const void *buf, PINDEX len)
virtual PBoolean	Shutdown (ShutdownValue option)
virtual PChannel *	GetBaseReadChannel () const
virtual PChannel *	GetBaseWriteChannel () const
virtual PString	GetErrorText (ErrorGroup group=NumErrorGroups) const
Channel establish functions
PBoolean	Open (PChannel &channel)
PBoolean	Open (PChannel *channel, PBoolean autoDelete=PTrue)
PBoolean	Open (PChannel *readChannel, PChannel *writeChannel, PBoolean autoDeleteRead=PTrue, PBoolean autoDeleteWrite=PTrue)
PChannel *	GetReadChannel () const
PBoolean	SetReadChannel (PChannel *channel, PBoolean autoDelete=PTrue)
PChannel *	GetWriteChannel () const
PBoolean	SetWriteChannel (PChannel *channel, PBoolean autoDelete=PTrue)
Protected Member Functions
virtual PBoolean	OnOpen ()
Protected Attributes
PChannel *	readChannel
	Channel for read operations.
PBoolean	readAutoDelete
	Automatically delete read channel on destruction.
PChannel *	writeChannel
	Channel for write operations.
PBoolean	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 PBoolean 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:

PTrue if the channel is closed.

Reimplemented from PChannel.

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

virtual PBoolean 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:

PTrue if the channel is open.

Reimplemented from PChannel.

virtual PBoolean 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 PFalse to determine what caused the failure.

Returns:

PTrue indicates that at least one character was read from the channel. PFalse 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 PBoolean 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 PFalse to determine what caused the failure.

Returns:

PTrue 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 PBoolean 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:

PTrue 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.

PBoolean 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 PTrue then the Open() function returns success.

Returns:

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

Parameters:

channel

Channel to be used for both read and write operations.

PBoolean PIndirectChannel::Open	(	PChannel *	channel,
		PBoolean	autoDelete = PTrue
	)

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 PTrue 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:

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

Parameters:

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

PBoolean PIndirectChannel::Open	(	PChannel *	readChannel,
		PChannel *	writeChannel,
		PBoolean	autoDeleteRead = PTrue,
		PBoolean	autoDeleteWrite = PTrue
	)

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 PTrue 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:

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

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.

PBoolean PIndirectChannel::SetReadChannel	(	PChannel *	channel,
		PBoolean	autoDelete = PTrue
	)

Set the channel for read operations.

Returns:

Returns PTrue 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.

PBoolean PIndirectChannel::SetWriteChannel	(	PChannel *	channel,
		PBoolean	autoDelete = PTrue
	)

Set the channel for read operations.

Returns:

Returns PTrue 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 PBoolean 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 PTrue.

Returns:

Returns PTrue 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.

PBoolean PIndirectChannel::readAutoDelete [protected]

Automatically delete read channel on destruction.

PChannel* PIndirectChannel::writeChannel [protected]

Channel for write operations.

PBoolean 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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