Networking API for Python

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Like many of the other object-oriented scripting languages, Python includes a standard Sockets layer (built into classes) and high-level APIs, providing methods to perform the standard Application layer protocols (HTTP, FTP, SMTP, and so on).

We’ll divide Python’s socket library into two distinct parts. The first are the class methods that require no instance of a socket class. For example, when creating a new socket, we’ll have no instance to go with. Therefore, we’ll use the socket class directly, specifically the socket method. The second are instance methods that require an instance of a socket. For example, to close a socket, we must have first created one. Therefore, the close method operates on an existing instance of the socket class. The class methods are shown in Figure 11.1 and the instance methods are listed in Figure 11.2.

Method	Class	Description
socket( [family[, type[, proto]]] )	socket	Create a new socket of the specified type.
gethostbyaddr( host )	socket	Return the hostname for a given IP address.
gethostbyname( host )	socket	Return the string IP address for a hostname.
gethostname( )	socket	Return the string hostname for the current host.
getservbyname( servicename, protocolname )	socket	Return the port number for a given string service.
htonl( integer )	socket	Convert from host to network 32-bit.
ntohl( integer )	socket	Convert from network to host 32-bit.
hton( short )	socket	Convert from host to network 16-bit.
ntohs( short )	socket	Convert from network to host 16-bit.
inet_aton( string )	socket	Convert a string IP address to binary format.
inet_ntoa( string )	socket	Convert a binary format string address to a string.

Figure 11.1: Python Sockets class methods.

Method	Type	Description
accept( )	Instance	Wait for incoming connections on a server socket instance.
bind( address )	Instance	Bind the socket instance to a local address.
close( )	Instance	Close the socket instance.
connect( address )	Instance	Connect the socket instance to the remove address.
fileno( )	Instance	Return the integer file descriptor for a socket instance.
getpeername( ) format.	Instance	Return the address of the remove endpoint in (host, port).
getsockname( )	Instance	Return the address of the local socket in (host, port) format.
getsockopt( level, option[, size] ))	Instance	Return the value of the socket option for the socket instance.
setsockopt( level, option, value )	Instance	Set the value of a socket option for a socket instance.
listen( backlog )	Instance	Enable the server socket to listen for incoming connections.
recv( size[, flags] )	Instance	Receive up to size bytes from the peer socket.
recvfrom( size[, flags] )	Instance	Receive up to size bytes. Response is (data, address).
send( data[, flags] )	Instance	Send the data bytes to the connected peer.
sendto( data[, flags], address )	Instance	Send the data bytes in datagram format to the peer defined by address.
setblocking( flag )	Instance	Set the socket to blocking or non-blocking (true/false).
shutdown( flag )	Instance	Shutdown the socket (0=read, 1=write, 2=both).

Figure 11.2: Python Sockets instance methods.

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