SGSocketUDP Class Reference

A UDP socket I/O class based on SGIOChannel and plib/net. More...

#include <sg_socket_udp.hxx>

Inheritance diagram for SGSocketUDP:

Public Member Functions
	SGSocketUDP (const string &host, const string &port)
	Create an instance of SGSocketUDP.
	~SGSocketUDP ()
	Destructor.
bool	open (const SGProtocolDir d)
	Open a channel.
int	read (char *buf, int length)
	The read() method is modeled after the read() Unix system call.
int	readline (char *buf, int length)
	The readline() method is similar to read() except that it will stop at the first end of line encountered in the input buffer.
int	write (const char *buf, const int length)
	The write() method is modeled after the write() Unix system call and is analogous to the read() method.
int	writestring (const char *str)
	The writestring() method is a simple wrapper that will calculate the length of a null terminated character array and write it to the output channel.
bool	close ()
	The close() method is modeled after the close() Unix system call and will close an open device.
bool	setBlocking (bool value)
	Set blocking true or false.
string	get_hostname () const
string	get_port_str () const

Detailed Description

A UDP socket I/O class based on SGIOChannel and plib/net.

Definition at line 49 of file sg_socket_udp.hxx.

Constructor & Destructor Documentation

SGSocketUDP::SGSocketUDP	(	const string &	host,
		const string &	port
	)

Create an instance of SGSocketUDP.

When calling the constructor you need to provide a host name, and a port number. The convention used by the SGSocketUDP class is that the server side listens and the client side sends. For a server socket, the host name should be empty. For a server, the port number is optional, if you do not specify a port, the system will assign one. For a client socket, you need to specify both a destination host and destination port.

UDP sockets are a lower level protocol than TCP sockets and are "connectionless" in the sense that either client or server can exist, or not exist, startup, quit, etc. in any order and whenever both ends are alive, the communication succeeds. With UDP sockets, the server end just sits and listens for incoming packets from anywhere. The client end sends it's message and forgets about it. It doesn't care if there isn't even a server out there listening and all the packets are getting lost. Although systems/networks usually do a pretty good job (statistically) of getting your UDP packets to their destination, there is no guarantee that any particular packet will make it. But, because of this low level implementation and lack of error checking, UDP packets are much faster and efficient. UDP packets are good for sending positional information to synchronize two applications. In this case, you want the information to arrive as quickly as possible, and if you lose a packet, you'd rather get new updated information rather than have the system waste time resending a packet that is becoming older and older with every retry.

Parameters:

	host	name of host if direction is SG_IO_OUT or SG_IO_BI
	port	port number if we care to choose one.
	style	specify "udp" or "tcp"

Definition at line 38 of file sg_socket_udp.cxx.

Member Function Documentation

bool SGSocketUDP::close ( ) [virtual]

The close() method is modeled after the close() Unix system call and will close an open device.

You should call this method when you are done using your IO class, before it is destructed.

Returns:: result of close

Reimplemented from SGIOChannel.

Definition at line 189 of file sg_socket_udp.cxx.

string SGSocketUDP::get_hostname ( ) const [inline]

Returns:: the remote host name

Definition at line 131 of file sg_socket_udp.hxx.

string SGSocketUDP::get_port_str ( ) const [inline]

Returns:: the port number (in string form)

Definition at line 134 of file sg_socket_udp.hxx.

bool SGSocketUDP::open ( const SGProtocolDir d ) [virtual]

Open a channel.

Parameters:

d

channel communication "direction" Direction can be one of:

SG_IO_IN - data will be flowing into this object to the application.
SG_IO_OUT - data will be flowing out of this object from the application.
SG_IO_BI - data will be flowing in both directions.
SG_IO_NONE - data will not be flowing in either direction. This is here for the sake of completeness.

Returns:: result of open

Reimplemented from SGIOChannel.

Definition at line 54 of file sg_socket_udp.cxx.

int SGSocketUDP::read	(	char *	buf,
		int	length
	)			`[virtual]`

The read() method is modeled after the read() Unix system call.

You must provide a pointer to a character buffer that has enough allocated space for your potential read. You can also specify the maximum number of bytes allowed for this particular read. The actual number of bytes read is returned. You are responsible to ensure that the size of buf is large enough to accomodate your input message

Parameters:

	buf	a char pointer to your input buffer
	length	max number of bytes to read

Returns:: number of bytes read

Reimplemented from SGIOChannel.

Definition at line 101 of file sg_socket_udp.cxx.

int SGSocketUDP::readline	(	char *	buf,
		int	length
	)			`[virtual]`

The readline() method is similar to read() except that it will stop at the first end of line encountered in the input buffer.

Parameters:

	buf	a char pointer to your input buffer
	length	max number of bytes to read

Returns:: number of bytes read

Reimplemented from SGIOChannel.

Definition at line 118 of file sg_socket_udp.cxx.

bool SGSocketUDP::setBlocking ( bool value )

Set blocking true or false.

Returns:: success/failure

Definition at line 201 of file sg_socket_udp.cxx.

int SGSocketUDP::write	(	const char *	buf,
		const int	length
	)			`[virtual]`

The write() method is modeled after the write() Unix system call and is analogous to the read() method.

You provide a pointer to a buffer of data, and then length of that data to be written out. The number of bytes written is returned.

Parameters:

	buf	a char pointer to your output buffer
	length	number of bytes to write

Returns:: number of bytes written

Reimplemented from SGIOChannel.

Definition at line 160 of file sg_socket_udp.cxx.

int SGSocketUDP::writestring ( const char * str ) [virtual]

The writestring() method is a simple wrapper that will calculate the length of a null terminated character array and write it to the output channel.

Parameters:

buf

a char pointer to your output buffer

Returns:: number of bytes written

Reimplemented from SGIOChannel.

Definition at line 178 of file sg_socket_udp.cxx.

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

SGSocketUDP Class Reference

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation