Provided by: afnix_3.8.0-1_amd64 
NAME
net - standard networking module
STANDARD NETWORKING MODULE
The Standard Networking module is an original implementation of networking facilities for
the Internet Protocol. The module features standard TCP and UDP sockets for point to point
communication as well as multicast socket. Numerous functions and objects for address
manipulation are also included in this module. This module is also designed to support IP
version 6 with certain platforms.
IP address
The IP based communication uses a standard address to reference a particular peer. With IP
version 4, the standard dot notation is with 4 bytes. With IP version 6, the standard
semicolon notation is with 16 bytes. The current implementation supports both versions.
127.0.0.1 # ipv4 localhost
0:0:0:0:0:0:0:1 # ipv6 localhost
IP address architecture and behavior are described in various documents as listed in the
bibliography.
Domain name system
The translation between a host name and an IP address is performed by a resolver which
uses the Domain Name System or DNS. Access to the DNS is automatic with the
implementation. Depending on the machine resolver configuration, a particular domain name
translation might result in an IP version 4 or IP version 6 address. Most of the time, an
IP version 4 address is returned. The mapping between an IP address and a host name
returns the associated canonical name for that IP address. This is the reverse of the
preceding operation.
The Address class
The Address class allows manipulation of IP address. The constructor takes a string as its
arguments. The argument string can be either an IP address or a host name which can be
qualified or not. When the address is constructed with a host name, the IP address
resolution is done immediately.
Name to address translation
The most common operation is to translate a host name to its equivalent IP address. Once
the Address object is constructed, the get-address method returns a string representation
of the internal IP address. The following example prints the IP address of the localhost,
that is 127.0.0.1 with IP version 4.
# load network module
interp:library "afnix-net"
# get the localhost address
const addr (afnix:net:Address "localhost")
# print the ip address
println (addr:get-address)
As another example, the get-host-name function returns the host name of the running
machine. The previous example can be used to query its IP address.
Address to name translation
The reverse operation of name translation maps an IP address to a canonical name. It shall
be noted that the reverse lookup is not done automatically, unless the reverse flag is set
in the constructoor. The get-canonical-name method of the Address class returns such name.
Example XNET001.als is a demonstration program which prints the address original name, the
IP address and the canonical name. Fell free to use it with your favorite site to check
the equivalence between the original name and the canonical name.
# print the ip address information of the arguments
# usage: axi XNET001.als [hosts ...]
# get the network module
interp:library "afnix-net"
# print the ip address
const ip-address-info (host) {
try {
const addr (afnix:net:Address host true)
println "host name : " (addr:get-name)
println " ip address : " (addr:get-address)
println " canonical name : " (
addr:get-canonical-name)
# get aliases
const size (addr:get-alias-size)
loop (trans i 0) (< i size) (i:++) {
println " alias address : " (
addr:get-alias-address i)
println " alias name : " (
addr:get-alias-name i)
}
} (errorln "error: " what:reason)
}
# get the hosts
for (s) (interp:argv) (ip-address-info s)
zsh> axi net-0001.als localhost
host name : localhost
ip address : 127.0.0.1
canonical name : localhost
Address operations
The Address class provides several methods and operators that ease the address
manipulation in a protocol indepedant way. For example, the == operator compares two
addresses. The ++ operator can also be used to get the next IP address.
Transport layers
The two transport layer protocols supported by the Internet protocol is the TCP, a full-
duplex oriented protocol, and UDP, a datagram protocol. TCP is a reliable protocol while
UDP is not. By reliable, we mean that the protocol provides automatically some mechanisms
for error recovery, message delivery, acknowledgment of reception, etc... The use of TCP
vs. UDP is dictated mostly by the reliability concerns, while UDP reduces the traffic
congestion.
Service port
In the client-server model, a connection is established between two hosts. The connections
is made via the IP address and the port number. For a given service, a port identifies
that service at a particular address. This means that multiple services can exist at the
same address. More precisely, the transport layer protocol is also used to distinguish a
particular service. The network module provides a simple mechanism to retrieve the port
number, given its name and protocol. The function get-tcp-service and get-udp-service
returns the port number for a given service by name. For example, the daytime server is
located at port number 13.
assert 13 (afnix:net:get-tcp-service "daytime")
assert 13 (afnix:net:get-udp-service "daytime")
Host and peer
With the client server model, the only information needed to identify a particular client
or server is the address and the port number. When a client connects to a server, it
specify the port number the server is operating. The client uses a random port number for
itself. When a server is created, the port number is used to bind the server to that
particular port. If the port is already in use, that binding will fail. From a reporting
point of view, a connection is therefore identified by the running host address and port,
and the peer address and port. For a client, the peer is the server. For a server, the
peer is the client.
TCP client socket
The TcpClient class creates an TCP client object by address and port. The address can be
either a string or an Address object. During the object construction, the connection is
established with the server. Once the connection is established, the client can use the
read and write method to communicate with the server. The TcpClient class is derived from
the Socket class which is derived from the InputStream and OutputStream classes.
Day time client
The simplest example is a client socket which communicates with the daytime server. The
server is normally running on all machines and is located at port 13.
# get the network module
interp:library "afnix-net"
# get the daytime server port
const port (afnix:net:get-tcp-service "daytime")
# create a tcp client socket
const s (afnix:net:TcpClient "localhost" port)
# read the data - the server close the connection
while (s:valid-p) (println (s:readln))
Example 3201.als in the example directory prints the day time of the local host without
argument or the day time of the argument. Feel free to use it with www.afnix.org. If the
server you are trying to contact does not have a day time server, an exception will be
raised and the program terminates.
zsh> axi 3201.als www.afnix.org
HTTP request example
Another example which illustrates the use of the TcpClient object is a simple client which
download a web page. At this stage we are not concern with the URL but rather the
mechanics involved. The request is made by opening a TCP client socket on port 80 (the
HTTP server port) and sending a request by writing some HTTP commands. When the commands
have been sent, the data sent by the server are read and printed on the standard output.
Note that this example is not concerned by error detection.
# fetch an html page by host and page
# usage: axi 3203.als [host] [page]
# get the network module
interp:library "afnix-net"
interp:library "afnix-sys"
# connect to the http server and issue a request
const send-http-request (host page) {
# create a client sock on port 80
const s (afnix:net:TcpClient host 80)
const saddr (s:get-socket-address)
# format the request
s:writeln "GET " page " HTTP/1.1"
s:writeln "Host: " (saddr:get-canonical-name)
s:writeln "Connection: close"
s:writeln "User-Agent: afnix tcp client example"
s:newline
# write the result
while (s:valid-p) (println (s:readln))
}
# get the argument
if (!= (interp:argv:length) 2) (afnix:sys:exit 1)
const host (interp:argv:get 0)
const page (interp:argv:get 1)
# send request
send-http-request host page
UDP client socket
UDP client socket is similar to TCP client socket. However, due to the unreliable nature
of UDP, UDP clients are somehow more difficult to manage. Since there is no flow control,
it becomes more difficult to assess whether or not a datagram has reached its destination.
The same apply for a server, where a reply datagram might be lost. The UdpClient class is
the class which creates a UDP client object. Its usage is similar to the TcpClient.
The time client
The UDP time server normally runs on port 37 is the best place to enable it. A UDP client
is created with the UdpClient class. Once the object is created, the client sends an empty
datagram to the server. The server send a reply datagram with 4 bytes, in network byte
order, corresponding to the date as of January 1st 1900. Example 3204.als prints date
information after contacting the local host time server or the host specified as the first
argument.
# get the libraries
interp:library "afnix-net"
interp:library "afnix-sys"
# get the daytime server port
const port (afnix:net:get-udp-service "time")
# create a client socket and read the data
const print-time (host) {
# create a udp client socket
const s (afnix:net:UdpClient host port)
# send an empty datagram
s:write
# read the 4 bytes data and adjust to epoch
const buf (s:read 4)
const val (- (buf:get-quad) 2208988800)
# format the date
const time (afnix:sys:Time val)
println (time:format-date) ' ' (time:format-time)
}
# check for one argument or use localhost
const host (if (== (interp:argv:length) 0)
"localhost" (interp:argv:get 0))
print-time host
This example calls for several comments. First the write method without argument sends an
empty datagram. It is the datagram which trigger the server. The read method reads 4 bytes
from the reply datagram and places them in a Buffer object. Since the bytes are in network
byte order, the conversion into an integer value is done with the get-quad method.
Finally, in order to use the Time class those epoch is January 1st 1970, the constant
2208988800 is subtracted from the result. Remember that the time server sends the date in
reference to January 1st 1900. More information about the time server can be found in
RFC738.
More on reliability
The previous example has some inherent problems due to the unreliability of UDP. If the
first datagram is lost, the read method will block indefinitely. Another scenario which
causes the read method to block is the loss of the server reply datagram. Both problem can
generally be fixed by checking the socket with a timeout using the valid-p method. With
one argument, the method timeout and return false. In this case, a new datagram can be
send to the server. Example 3205.als illustrates this point. We print below the extract of
code.
# create a client socket and read the data
const print-time (host) {
# create a udp client socket
const s (afnix:net:UdpClient host port)
# send an empty datagram until the socket is valid
s:write
# retransmit datagram each second
while (not (s:valid-p 1000)) (s:write)
# read the 4 bytes data and adjust to epoch
const buf (s:read 4)
const val (- (buf:get-quad) 2208988800)
# format the date
const time (afnix:sys:Time val)
println (time:format-date) ' ' (time:format-time)
}
Note that this solution is a naive one. In the case of multiple datagrams, a sequence
number must be placed because there is no clue about the lost datagram. A simple rule of
thumb is to use TCP as soon as reliability is a concern, but this choice might not so
easy.
Error detection
Since UDP is not reliable, there is no simple solution to detect when a datagram has been
lost. Even worse, if the server is not running, it is not easy to detect that the client
datagram has been lost. In such situation, the client might indefinitely send datagram
without getting an answer. One solution to this problem is again to count the number of
datagram re-transmit and eventually give up after a certain time.
Socket class
The Socket class is the base class for both TcpClient and UdpClient. The class provides
methods to query the socket port and address as well as the peer port and address. Note at
this point that the UDP socket is a connected socket. Therefore, these methods will work
fine. The get-socket-address and get-socket-port returns respectively the address and port
of the connected socket. The get-peer-address and get-peer-port returns respectively the
address and port of the connected socket's peer. Example 3206.als illustrates the use of
these methods.
# create a client socket and read the data
const print-socket-info (host) {
# create a tcp client socket
const s (afnix:net:TcpClient host port)
# print socket address and port
const saddr (s:get-socket-address)
const sport (s:get-socket-port)
println "socket ip address : " (
saddr:get-address)
println "socket canonical name : " (
saddr:get-canonical-name)
println "socket port : " sport
# print peer address and port
const paddr (s:get-peer-address)
const pport (s:get-peer-port)
println "peer ip address : " (
paddr:get-address)
println "peer canonical name : " (
paddr:get-canonical-name)
println "peer port : " pport
}
Socket predicates
The Socket class is associated with the socket-p predicate. The respective client objects
have the tcp-client-p predicate and udp-client-p predicate.
TCP server socket
The TcpServer class creates an TCP server object. There are several constructors for the
TCP server. In its simplest form, without port, a TCP server is created on the localhost
with an ephemeral port number (i.e port 0 during the call). With a port number, the TCP
server is created on the localhost. For a multi-homed host, the address to use to run the
server can be specified as the first argument. The address can be either a string or an
Address object. In both cases, the port is specified as the second argument. Finally, a
third argument called the backlog can be specified to set the number of acceptable
incoming connection. That is the maximum number of pending connection while processing a
connection. The following example shows various ways to create a TCP server.
trans s (afnix:net:TcpServer)
trans s (afnix:net:TcpServer 8000)
trans s (afnix:net:TcpServer 8000 5)
trans s (afnix:net:TcpServer "localhost" 8000)
trans s (afnix:net:TcpServer "localhost" 8000 5)
trans s (afnix:net:TcpServer (
Address "localhost") 8000)
trans s (afnix:net:TcpServer (
Address "localhost") 8000 5)
Echo server example
A simple echo server can be built and tested with the standard telnet application. The
application will echo all lines that are typed with the telnet client. The server is bound
on the port 8000, since ports 0 to 1024 are privileged ports.
# get the network module
interp:library "afnix-net"
# create a tcp server on port 8000
const srv (afnix:net:TcpServer 8000)
# wait for a connection
const s (srv:accept)
# echo the line until the end
while (s:valid-p) (s:writeln (s:readln))
The telnet session is then quite simple. The line hello world is echoed by the server.
zsh> telnet localhost 8000
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
hello world
^D
The accept method
The previous example illustrates the mechanics of a server. When the server is created,
the server is ready to accept connection. The accept method blocks until a client connect
with the server. When the connection is established, the accept method returns a socket
object which can be used to read and write data.
Multiple connections
One problem with the previous example is that the server accepts only one connection. In
order to accept multiple connection, the accept method must be placed in a loop, and the
server operation in a thread (There are some situations where a new process might be more
appropriate than a thread). Example 3302.als illustrates such point.
# get the network module
interp:library "afnix-net"
# this function echo a line from the client
const echo-server (s) {
while (s:valid-p) (s:writeln (s:readln))
}
# create a tcp server on port 8000
const srv (afnix:net:TcpServer 8000)
# wait for a connection
while true {
trans s (srv:accept)
launch (echo-server s)
}
UDP server socket
The UdpServer class is similar to the TcpServer object, except that there is no backlog
parameters. In its simplest form, the UDP server is created on the localhost with an
ephemeral port (i.e port 0). With a port number, the server is created on the localhost.
For a multi-homed host, the address used to run the server can be specified as the first
argument. The address can be either a string or an Address object. In both cases, the port
is specified as the second argument.
trans s (afnix:net:UdpServer)
trans s (afnix:net:UdpServer 8000)
trans s (afnix:net:UdpServer "localhost" 8000)
trans s (afnix:net:UdpServer (
Address "localhost") 8000)
Echo server example
The echo server can be revisited to work with udp datagram. The only difference is the use
of the accept method. For a UDP server, the method return a Datagram object which can be
used to read and write data.
# get the network module
interp:library "afnix-net"
# create a udp server on port 8000
const srv (afnix:net:UdpServer 8000)
# wait for a connection
while true {
trans dg (srv:accept)
dg:writeln (dg:readln)
}
Datagram object
With a UDP server, the accept method returns a Datagram object. Because a UDP is
connection-less, the server has no idea from whom the datagram is coming until that one
has been received. When a datagram arrives, the Datagram object is constructed with the
peer address being the source address. Standard i/o methods can be used to read or write.
When a write method is used, the data are sent back to the peer in a form of another
datagram.
# wait for a datagram
trans dg (s:accept)
# assert datagram type
assert true (datagram-p dg)
# get contents length
println "datagram buffer size : " (dg:get-buffer-length)
# read a line from this datagram
trans line (dg:readln)
# send it back to the sender
s:writeln line
Input data buffer
For a datagram, and generally speaking, for a UDP socket, all input operations are
buffered. This means that when a datagram is received, the accept method places all data
in an input buffer. This means that a read operation does not necessarily flush the whole
buffer but rather consumes only the requested character. For example, if one datagram
contains the string hello world. A call to readln will return the entire string. A call to
read will return only the character 'h'. Subsequent call will return the next available
characters. A call like read 5 will return a buffer with 5 characters. Subsequent calls
will return the remaining string. In any case, the get-buffer-length will return the
number of available characters in the buffer. A call to valid-p will return true if there
are some characters in the buffer or if a new datagram has arrived. Care should be taken
with the read method. For example if there is only 4 characters in the input buffer and a
call to read for 10 characters is made, the method will block until a new datagram is
received which can fill the remaining 6 characters. Such situation can be avoided by using
the get-buffer-length and the valid-p methods. Note also that a timeout can be specified
with the valid-p method.
Low level socket methods
Some folks always prefer to do everything by themselves. Most of the time for good
reasons. If this is your case, you might have to use the low level socket methods. Instead
of using a client or server class, the implementation let's you create a TcpSocket or
UdpSocket. Once this done, the bind, connect and other methods can be used to create the
desired connection.
A socket client
A simple TCP socket client is created with the TcpSocket class. Then the connect method is
called to establish the connection.
# create an address and a tcp socket
const addr (afnix:net:Address "localhost")
const sid (afnix:net:TcpSocket)
# connect the socket
sid:connect 13 addr
Once the socket is connected, normal read and write operations can be performed. After the
socket is created, it is possible to set some options. A typical one is NO-DELAY which
disable the Naggle algorithm.
# create an address and a tcp socket
const addr (afnix:net:Address "localhost")
const sid (afnix:net:TcpSocket)
# disable the naggle algorithm
sid:set-option sid:NO-DELAY true
# connect the socket
sid:connect 13 addr
NETWORKING REFERENCE
Address
The Address class is the Internet address manipulation class. The class can be used to
perform the conversion between a host name and an IP address. The opposite is also
possible. Finally, the class supports both IP version 4 and IP version 6 address formats.
Predicate
address-p
Inheritance
Object
Constructors
Address (String)
The Address constructor create an IP address object by name. The name argument is a
string of a host name or a valid IP address representation.
Address (String Boolean)
The Address constructor create an IP address object by name and force the reverse
lookup resolution depending on the boolean flag value. The first argument is a
string of a host name or a valid IP address representation. The second argument is
a boolean flag that indicates whether or not reverse lookup must occur during the
construction.
Operators
== -> Boolean (Address)
The == operator returns true if the calling object is equal to the address
argument.
!= -> Boolean (Address)
The != operator returns true if the calling object is not equal to the address
argument.
< -> Boolean (Address)
The < operator returns true if the calling address is less than the address object.
<= -> Boolean (Address)
The <= operator returns true if the calling address is less equal than the address
object.
> -> Boolean (Address)
The > operator returns true if the calling address is greater than the address
object.
>= -> Boolean (Address)
The <= operator returns true if the calling address is greater equal than the
address object.
++ -> Address (Address)
The ++ operator increments the calling address by one position.
Methods
resolve -> String Boolean (none)
The resolve method resolves an host name and eventually performs a reverse lookup.
The first argument is a string of a host name or a valid IP address representation.
The second argument is a boolean flag that indicates whether or not reverse lookup
must occur during the resolution.
get-name -> String (none)
The get-name method returns the original name used during the object construction.
get-address -> String (none)
The get-address method returns a string representation of the IP address. The
string representation follows the IP version 4 or IP version 6 preferred formats,
depending on the internal representation.
get-vector -> Vector (none)
The get-vector method returns a vector representation of the IP address. The vector
result follows the IP version 4 or IP version 6 preferred format, depending on the
internal representation.
get-canonical-name -> String (none)
The get-canonical-name method returns a fully qualified name of the address. The
resulting name is obtained by performing a reverse lookup. Note that the name can
be different from the original name.
get-alias-size -> Integer (none)
The get-alias-size method returns the number of aliases for the address. The number
of aliases includes as well the primary resolved name which is located at index 0.
get-alias-name -> String (Integer)
The get-alias-name method returns a fully qualified name of the address alias by
index. The first argument is the alias index number which must be in the alias
index range. The resulting name is obtained by performing a reverse lookup. Note
that the name can be different from the original name. Using index 0 is equivalent
to call get-canonical-name.
get-alias-address -> String (Integer)
The get-alias-address method returns a string representation of the IP address
alias by index. The first argument is the alias index number which must be in the
alias index range. The string representation follows the IP version 4 or IP version
6 preferred formats, depending on the internal representation. Using index 0 is
equivalent to call get-address.
get-alias-vector -> Vector (Integer)
The get-alias-vector method returns a vector representation of the IP address alias
by index. The first argument is the alias index number which must be in the alias
index range. The vector result follows the IP version 4 or IP version 6 preferred
format, depending on the internal representation. Using index 0 is equivalent to
call get-vector.
Functions
get-loopback -> String (none)
The get-loopback function returns the name of the machine loopback. On a UNIX
system, that name is localhost.
get-tcp-service -> String (Integer)
The get-tcp-service function returns the name of the tcp service given its port
number. For example, the tcp service at port 13 is the daytime server.
get-udp-service -> String (Integer)
The get-udp-service function returns the name of the udp service given its port
number. For example, the udp service at port 19 is the chargen server.
Socket
The Socket class is a base class for the AFNIX network services. The class is
automatically constructed by a derived class and provide some common methods for all
socket objects.
Predicate
socket-p
Inheritance
InputStreamOutputStream
Constants
REUSE-ADDRESS
The REUSE-ADDRESS constant is used by the set-option method to enable socket
address reuse. This option changes the rules that validates the address used by
bind. It is not recommended to use that option as it decreases TCP reliability.
BROADCAST
The BROADCAST constant is used by the set-option method to enable broadcast of
packets. This options only works with IP version 4 address. The argument is a
boolean flag only.
DONT-ROUTE
The DONT-ROUTE constant is used by the set-option method to control if a packet is
to be sent via the routing table. This option is rarely used with . The argument is
a boolean flag only.
KEEP-ALIVE
The KEEP-ALIVE constant is used by the set-option method to check periodically if
the connection is still alive. This option is rarely used with . The argument is a
boolean flag only.
LINGER
The LINGER constant is used by the set-option method to turn on or off the
lingering on close. If the first argument is true, the second argument is the
linger time.
RCV-SIZE
The RCV-SIZE constant is used by the set-option method to set the receive buffer
size.
SND-SIZE
The SND-SIZE constant is used by the set-option method to set the send buffer size.
HOP-LIMIT
The HOP-LIMIT constant is used by the set-option method to set packet hop limit.
MULTICAST-LOOPBACK
The MULTICAST-LOOPBACK constant is used by the set-option method to control whether
or not multicast packets are copied to the loopback. The argument is a boolean flag
only.
MULTICAST-HOP-LIMIT
The MULTICAST-HOP-LIMIT constant is used by the set-option method to set the hop
limit for multicast packets.
MAX-SEGMENT-SIZE
The MAX-SEGMENT-SIZE constant is used by the set-option method to set the TCP
maximum segment size.
NO-DELAY
The NO-DELAY constant is used by the set-option method to enable or disable the
Naggle algorithm.
Methods
bind -> none (Integer)
The bind method binds this socket to the port specified as the argument.
bind -> none (Integer Address)
The bind method binds this socket to the port specified as the first argument and
the address specified as the second argument.
connect -> none (Integer Address [Boolean])
The connect method connects this socket to the port specified as the first argument
and the address specified as the second argument. A connected socket is useful with
udp client that talks only with one fixed server. The optional third argument is a
boolean flag that permits to select whether or not the alias addressing scheme
should be used. If the flag is false, the default address is used. If the flag is
true, an attempt is made to connect to the first successful address that is part of
the alias list.
open-p -> Boolean (none)
The open-p predicate returns true if the socket is open. The method checks that a
descriptor is attached to the object. This does not mean that the descriptor is
valid in the sense that one can read or write on it. This method is useful to check
if a socket has not been closed.
shutdown -> Boolean (none|Boolean)
The shutdown method shutdowns or close the connection. Without argument, the
connection is closed without consideration for those symbols attached to the
object. With one argument, the connection is closed in one direction only. If the
mode argument is false, further receive is disallowed. If the mode argument is
true, further send is disallowed. The method returns true on success, false
otherwise.
ipv6-p -> Boolean (none)
The ipv6-p predicate returns true if the socket address is an IP version 6 address,
false otherwise.
get-socket-address -> Address (none)
The get-socket-address method returns an address object of the socket. The returned
object can be later used to query the canonical name and the ip address.
get-socket-port -> Integer (none)
The get-socket-port method returns the port number of the socket.
get-socket-authority -> String (none)
The get-socket-authority method returns the authority string in the form of an
address and port pair of the socket.
get-peer-address -> Address (none)
The get-peer-address method returns an address object of the socket's peer. The
returned object can be later used to query the canonical name and the ip address.
get-peer-port -> Integer (none)
The get-peer-port method returns the port number of the socket's peer.
get-peer-authority -> String (none)
The get-peer-authority method returns the authority string in the form of an
address and port pair of the socket's peer.
set-option -> Boolean (constant [Boolean|Integer] [Integer])
The set-option method set a socket option. The first argument is the option to set.
The second argument is a boolean value which turn on or off the option. The
optional third argument is an integer needed for some options.
set-encoding-mode -> none (Item|String)
The set-encoding-mode method sets the input and output encoding mode. In the first
form, with an item, the stream encoding mode is set directly. In the second form,
the encoding mode is set with a string and might also alter the stream transcoing
mode.
set-input-encoding-mode -> none (Item|String)
The set-input-encoding-mode method sets the input encoding mode. In the first form,
with an item, the stream encoding mode is set directly. In the second form, the
encoding mode is set with a string and might also alter the stream transcoing mode.
get-input-encoding-mode -> Item (none)
The get-input-encoding-mode method return the input encoding mode.
set-output-encoding-mode -> none (Item|String)
The set-output-encoding-mode method sets the output encoding mode. In the first
form, with an item, the stream encoding mode is set directly. In the second form,
the encoding mode is set with a string and might also alter the stream transcoing
mode.
get-output-encoding-mode -> Item (none)
The get-output-encoding-mode method return the output encoding mode.
TcpSocket
The TcpSocket class is a base class for all tcp socket objects. The class is derived from
the Socket class and provides some specific tcp methods. If a TcpSocket is created, the
user is responsible to connect it to the proper address and port.
Predicate
tcp-socket-p
Inheritance
Socket
Constructors
TcpSocket (none)
The TcpSocket constructor creates a new tcp socket.
Methods
accept -> TcpSocket (none)
The accept method waits for incoming connection and returns a TcpSocket object
initialized with the connected peer. The result socket can be used to perform i/o
operations. This method is used by tcp server.
listen -> Boolean (none|Integer)
The listen method initialize a socket to accept incoming connection. Without
argument, the default number of incoming connection is 5. The integer argument can
be used to specify the number of incoming connection that socket is willing to
queue. This method is used by tcp server.
TcpClient
The TcpClient class creates a tcp client by host and port. The host argument can be either
a name or an address object. The port argument is the server port to contact. The
TcpClient class is derived from the TcpSocket class. This class has no specific methods.
Predicate
tcp-client-p
Inheritance
TcpSocket
Constructors
TcpClient (String Integer)
The TcpClient constructor creates a new tcp client socket by host name and port
number.
TcpServer
The TcpServer class creates a tcp server by port. An optional host argument can be either
a name or an address object. The port argument is the server port to bind. The TcpServer
class is derived from the TcpSocket class. This class has no specific methods. With one
argument, the server bind the port argument on the local host. The backlog can be
specified as the last argument. The host name can also be specified as the first argument,
the port as second argument and eventually the backlog. Note that the host can be either a
string or an address object.
Predicate
tcp-server-p
Inheritance
TcpSocket
Constructors
TcpServer (none)
The TcpServer constructor creates a default tcp server.
TcpServer (Integer)
The TcpServer constructor creates a default tcp server which is bound on the
specified port argument.
TcpServer (Integer Integer)
The TcpServer constructor creates a default tcp server which is bound on the
specified port argument. The second argument is the backlog value.
TcpServer (String Integer)
The TcpServer constructor creates a tcp server by host name and port number. The
first argument is the host name. The second argument is the port number.
TcpServer (String Integer Integer)
The TcpServer constructor creates a tcp server by host name and port number. The
first argument is the host name. The second argument is the port number. The third
argument is the backlog.
Datagram
The Datagram class is a socket class used by udp socket. A datagram is constructed by the
UdpSocketaccept method. The purpose of a datagram is to store the peer information so one
can reply to the sender. The datagram also stores in a buffer the data sent by the peer.
This class does not have any constructor nor any specific method.
Predicate
datagram-p
Inheritance
Socket
UdpSocket
The UdpSocket class is a base class for all udp socket objects. The class is derived from
the Socket class and provides some specific udp methods.
Predicate
udp-socket-p
Inheritance
Socket
Constructors
UdpSocket (none)
The UdpSocket constructor creates a new udp socket.
Methods
accept -> Datagram (none)
The accept method waits for an incoming datagram and returns a Datagram object. The
datagram is initialized with the peer address and port as well as the incoming
data.
UdpClient
The UdpClient class creates a udp client by host and port. The host argument can be either
a name or an address object. The port argument is the server port to contact. The
UdpClient class is derived from the UdpSocket class. This class has no specific methods.
Predicate
udp-client-p
Inheritance
UdpSocket
Constructors
UdpClient (String Integer)
The UdpClient constructor creates a new udp client by host and port. The first
argument is the host name. The second argument is the port number.
UdpServer
The UdpServer class creates a udp server by port. An optional host argument can be either
a name or an address object. The port argument is the server port to bind. The UdpServer
class is derived from the UdpSocket class. This class has no specific methods. With one
argument, the server bind the port argument on the local host. The host name can also be
specified as the first argument, the port as second argument. Note that the host can be
either a string or an address object.
Predicate
udp-server-p
Inheritance
UdpSocket
Constructors
UdpServer (none)
The UdpServer constructor creates a default udp server object.
UdpServer (String|Address)
The UdpServer constructor creates a udp server object by host. The first argument
is the host name or host address.
UdpServer (String|Address Integer)
The UdpServer constructor creates a udp server object by host and port. The first
argument is the host name or host address. The second argument is the port number.
Multicast
The Multicast class creates a udp multicast socket by port. An optional host argument can
be either a name or an address object. The port argument is the server port to bind. The
Multicast class is derived from the UdpSocket class. This class has no specific methods.
With one argument, the server bind the port argument on the local host. The host name can
also be specified as the first argument, the port as second argument. Note that the host
can be either a string or an address object. This class is similar to the UdpServer class,
except that the socket join the multicast group at construction and leave it at
destruction.
Predicate
multicast-p
Inheritance
UdpSocket
Constructors
Multicast (String|Address)
The Multicast constructor creates a multicast socket object by host. The first
argument is the host name or host address.
Multicast (String|Address Integer)
The Multicast constructor creates a multicast socket object by host and port. The
first argument is the host name or host address. The second argument is the port
number.