In {object-oriented programming} sending a message to an
	{object} (to invoke a {method}) is equivalent to calling a
	{procedure} in traditional programming languages, except that
	the actual code executed may only be selected at run time
	depending on the {class} of the object.  Thus, in response to
	the message "drawSelf", the method code invoked would be
	different if the target object were a circle or a square.

	(1995-02-16)

<library, networking> {Unix} socket library routine to connect
	a socket that has been created on the local hosts to one at a
	specified socket address on the remote host.

	{Unix manual pages}: connect(2), accept(2).

	(1995-03-21)

<messaging> 1. {electronic mail}.

	2. The {Berkeley Unix} program for composing and reading
	{electronic mail}.  It normally uses {sendmail} to handle
	delivery.

	{Unix manual page}: mail(1)

	(1997-12-03)

1. A program which provides some service to other ({client})
	programs.  The connection between client and server is
	normally by means of {message passing}, often over a
	{network}, and uses some {protocol} to encode the client's
	requests and the server's responses.  The server may run
	continuously (as a {daemon}), waiting for requests to arrive
	or it may be invoked by some higher level daemon which
	controls a number of specific servers ({inetd} on {Unix}).

	There are many servers associated with the {Internet}, such as
	those for {HTTP}, {Network File System}, {Network Information
	Service} (NIS), {Domain Name System} (DNS), {FTP}, {news},
	{finger}, {Network Time Protocol}.  On Unix, a long list can
	be found in /etc/services or in the {NIS} database "services".
	See {client-server}.

	2. A computer which provides some service for other computers
	connected to it via a network.  The most common example is a
	{file server} which has a local disk and services requests
	from remote clients to read and write files on that disk,
	often using {Sun}'s {Network File System} (NFS) {protocol} or
	{Novell Netware} on {PCs}.  Another common example is a {web
	server}.

	[{Jargon File}]

	(2003-12-29)

1. <networking> A logical channel or channel endpoint in a
	communications system.  The {Transmission Control Protocol}
	and {User Datagram Protocol} {transport layer} protocols used
	on {Ethernet} use port numbers to distinguish between
	(demultiplex) different logical channels on the same {network
	interface} on a computer.

	Each {application program} has a unique port number associated
	with it, defined in /etc/services or the {Network Information
	Service} "services" database.  Some {protocols}, e.g. {telnet}
	and {HTTP} (which is actually a special form of telnet) have
	default ports specified as above but can use other ports as
	well.

	Some port numbers are defined in {RFC 3232} (which replaces
	RFC 1700).  Ports are now divided into: "Well Known" or
	"Privileged", and "Ephemeral" or "Unprivileged" (comprising
	"Registered", "Dynamic", "Private").

	(2004-12-30)

	2. <operating system, programming> To translate or modify
	{software} to run on a different {platform}, or the results of
	doing so.  The {portability} of the software determines how
	easy it is to port.

	3. <language> An {imperative} language descended from {Zed}
	from {Waterloo Microsystems} (now {Hayes} Canada) ca. 1979.

	["Port Language" document in the Waterloo Port Development
	System].

	(2002-06-19)

<messaging> (SMTP) A {protocol} defined in {STD} 10, {RFC}
	821, used to transfer {electronic mail} between computers,
	usually over {Ethernet}.  It is a server to server protocol,
	so other protocols are used to access the messages.  The SMTP
	dialog usually happens in the background under the control of
	the {message transfer agent}, e.g. {sendmail} but it is
	possible to interact with an SMTP server using {telnet} to
	connect to the normal SMTP {port}, 25.  E.g.

		telnet mhs-relay.ac.uk 25

	You should normally start by identifying the local {host}:

		HELO wombat.doc.ic.ac.uk

	You can then issue commands to verify an address or expand an
	alias:

		VRFY fred@doc.ic.ac.uk
		VRFY postmaster

	or expand a {mailing list}:

		EXPN c-help

	You can even send a message:

		MAIL From:<fred@doc.ic.ac.uk>
		RCPT To:<fred@mailway.doc.ic.ac.uk>
		DATA
		What is the point?
		.
		QUIT

	This is useful if you want to find out exactly what is
	happening to your message at a certain point.

	See also {Post Office Protocol}, {RFC 822}, {sendmail}.

	(1995-10-17)

1. See {multithreading}.

	2. See {threaded code}.

	3. {topic thread}.

	[{Jargon File}]

<jargon> A {marketroid} term for something he wants to sell
	you without bothering you with the often dizzying distinctions
	between {hardware}, {software}, {services}, {applications},
	{file formats}, companies, brand names and {operating
	systems}.

	"{Flash} is a perfect image-streaming solution."  "What is
	it?"  "Um...  about a thousand dollars."

	See also: {technology}.

	(1998-07-07)

1. {firewall code}.

	2. {firewall machine}.

1. <mathematics> In the theory of functions, the set of
	argument values for which a {function} is defined.

	See {domain theory}.

	2. <networking> A group of computers whose {hostnames} share a
	common suffix, the "domain name".  The last component of this
	is the {top-level domain}.

	See {administrative domain}, {Domain Name System}, {fully
	qualified domain name}.

	3. {Distributed Operating Multi Access Interactive Network}.

	4. <programming> A specific phase of the {software life cycle}
	in which a developer works.  Domains define developers' and
	users' areas of responsibility and the scope of possible
	relationships between products.

	5. The subject or market in which a piece of software is
	designed to work.

	(1997-12-26)

<chat, tool, networking, messaging> A {Unix} program and
	{protocol} supporting conversation between two or more users
	who may be logged into the same computer or different
	computers on a network.  Variants include {ntalk}, {ytalk},
	and {ports} or {emulators} of these programs for other
	{platforms}.

	{Unix} has the {talk} program and {protocol} and its variants
	{xtalk} and {ytalk} for the {X Window System}; {VMS} has
	{phone}; {Windows for Workgroups} has {chat}.  {ITS} also has
	a talk system.  These split the screen into separate areas for
	each user.

	{Unix}'s {write} command can also be used, though it does not
	attempt to separate input and output on the screen.

	Users of such systems are said to be in {talk mode} which has
	many conventional abbreviations and idioms.  Most of these
	survived into {chat} jargon, but many fell out of common use
	with the migration of {user} prattle from talk-like systems to
	{chat} systems in the early 1990s.  These disused
	talk-specific forms include:

	"BYE?" - are you ready to close the conversation?  This is the
	standard way to end a talk-mode conversation; the other person
	types "BYE" to confirm, or else continues the conversation.

	"JAM"/"MIN" - just a minute

	"O" - "over" (I have stopped talking).  Also "/" as in x/y - x
	over y, or two newlines (the latter being the most common).

	"OO" - "over and out" - end of conversation.

	"\" - Greek {lambda}.

	"R U THERE?" - are you there?

	"SEC" - wait a second.

	"/\/\/" - laughter.  But on a {MUD}, this usually means
	"earthquake fault".

	See also {talk bomb}.

	(1998-01-25)