<programming, operating system> (Or "application", "app") A
	complete, self-contained program that performs a specific
	function directly for the user.  This is in contrast to system
	software such as the {operating system} {kernel}, {server}
	processes and libraries which exists to support application
	programs.

	Editors for various kinds of documents, {spreadsheets}, and
	text formatters are common examples of applications.  Network
	applications include clients such as those for {FTP},
	{electronic mail}, {telnet} and {WWW}.

	The term is used fairly loosely, for instance, some might say
	that a client and server together form a distributed
	application, others might argue that editors and compilers
	were not applications but tools for building applications.

	One distinction between an application program and the
	operating system is that applications always run in "user
	mode" (or "non-privileged mode"), while operating systems and
	related utilities may run in "supervisor mode" (or "privileged
	mode").

	The term may also be used to distinguish programs which
	communicate via a {graphical user interface} from those which
	are executed from the {command line}.

	(1994-11-28)

<operating system, programming> The process of carrying out
	the {instructions} in a computer program by a computer.

	See also {dry run}.

	(1996-05-13)

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)

<programming> A computer system or process that requests a
	service of another computer system or process (a "{server}")
	using some kind of {protocol} and accepts the server's
	responses.  A client is part of a {client-server} software
	architecture.

	For example, a {workstation} requesting the contents of a file
	from a {file server} is a client of the file server.

	(1997-10-27)

Common term for "computer", usually when considered at the
	hardware level.  The {Turing Machine}, an early example of
	this usage, was however neither hardware nor software, but
	only an idea.

	[Earlier use?]

	(1995-02-15)

1. A discrepancy between a computed, observed, or measured
	value or condition and the true, specified, or theoretically
	correct value or condition.

	2. <programming> A mental mistake made by a programmer that
	may result in a program {fault}.

	3. (verb) What a program does when it stops as result of a
	programming error.

	(2000-03-28)

<programming> (ORB) Part of the {OMG} {CORBA} specification,
	an ORB's basic function is to pass {method} invocation
	requests to the correct {objects} and return the results to
	the caller.

	To achieve this the ORB must be able must be able to identify
	and locate objects, handle connections from invoker and the
	data returned from methods.  Communication between the ORB and
	applications are achieved through {IDL} stubs and skeletons
	whilst the OMG has specified {IIOP} as the protocol through
	which ORBs may communicate with each other.  Using IIOP, an
	ORB may request method invocations from a remote object.

	(2003-11-21)

<operating system> ("Linus Unix") /li'nuks/ (but see below)
	An implementation of the {Unix} {kernel} originally written
	from scratch with no proprietary code.

	The kernel runs on {Intel} and {Alpha} hardware in the general
	release, with {SPARC}, {PowerPC}, {MIPS}, {ARM}, {Amiga},
	{Atari}, and {SGI} in active development.  The SPARC, PowerPC,
	ARM, {PowerMAC} - {OSF}, and 68k ports all support {shells},
	{X} and {networking}.  The Intel and SPARC versions have
	reliable {symmetric multiprocessing}.

	Work on the kernel is coordinated by Linus Torvalds, who holds
	the copyright on a large part of it.  The rest of the
	copyright is held by a large number of other contributors (or
	their employers).  Regardless of the copyright ownerships, the
	kernel as a whole is available under the {GNU} {General Public
	License}.  The GNU project supports Linux as its kernel until
	the research {Hurd} kernel is completed.

	This kernel would be no use without {application programs}.
	The GNU project has provided large numbers of quality tools,
	and together with other {public domain} software it is a rich
	Unix environment.  A compilation of the Linux kernel and these
	tools is known as a Linux distribution.  Compatibility modules
	and/or {emulators} exist for dozens of other computing
	environments.

	The kernel version numbers are significant: the odd numbered
	series (e.g. 1.3.xx) is the development (or beta) kernel which
	evolves very quickly.  Stable (or release) kernels have even
	major version numbers (e.g. 1.2.xx).

	There is a lot of commercial support for and use of Linux,
	both by hardware companies such as {Digital}, {IBM}, and
	{Apple} and numerous smaller network and integration
	specialists.  There are many commercially supported
	distributions which are generally entirely under the GPL.  At
	least one distribution vendor guarantees {Posix} compliance.
	Linux is particularly popular for {Internet Service
	Providers}, and there are ports to both parallel
	supercomputers and {embedded} {microcontrollers}.  {Debian} is
	one popular {open source} distribution.

	The pronunciation of "Linux" has been a matter of much debate.
	Many, including Torvalds, insist on the short I pronunciation
	/li'nuks/ because "Linus" has an /ee/ sound in Swedish
	(Linus's family is part of Finland's 6% ethnic-Swedish
	minority) and Linus considers English short /i/ to be closer
	to /ee/ than English long /i:/ dipthong.  This is consistent
	with the short I in words like "linen".  This doesn't stop
	others demanding a long I /li:'nuks/ following the english
	pronunciation of "Linus" and "minus".  Others say /li'niks/
	following {Minix}, which Torvalds was working on before Linux.

	{More on pronunciation
	(http://www.foldoc.org/pub/linux-pronunciation)}.

	{LinuxHQ (http://www.linuxhq.com/)}.  {slashdot
	(http://slashdot.org/)}.  {freshmeat (http://freshmeat.net/)}.
	{Woven Goods (http://www.fokus.gmd.de/linux/)}.  {Linux
	Gazette (http://www.ssc.com/lg)}.

	{funet Linux Archive (ftp://ftp.funet.fi/pub/Linux)}, {US
	mirror (ftp://sunsite.unc.edu/pub/Linux/)}, {UK Mirror
	(ftp://sunsite.doc.ic.ac.uk/packages/Linux/)}.

	(2000-06-09)

<operating system> /deb'ee`n/, *not* /deeb'ee`n/ The
	non-profit volunteer organisation responsible for Debian
	{GNU}/{Linux} and Debian {GNU}/{Hurd}.  Debian's {Linux}
	distribution is dedicated to free and {open source} software;
	the main goal of the distribution is to ensure that one can
	download and install a fully-functional {operating system}
	that is completely adherent to the Debian Free Software
	Guidelines (DFSG).

	Debian was begun in August 1993 by Ian Murdock, and was
	sponsored by the {Free Software Foundation} from November 1994
	to November 1995.  The name Debian is a contraction of DEB(ra)
	and IAN Murdock.

	Debian's packaging system (dpkg) is similar to other popular
	packaging systems like {RPM}.  There are over 2200 packages of
	precompiled software available in the main (free) section of
	the Debian 2.1 distribution alone -- this is what sets Debian
	apart from many other Linux distributions.  The high quality
	and huge number of official packages (most Debian systems'
	/usr/local/ remains empty -- almost everything most Linux
	users want is officially packaged) are what draw many people
	to use Debian.

	Another unique aspect to the Debian project is the open
	development; pre-releases are made available from Day 1 and if
	anyone wishes to become a Debian developer, all that is needed
	is proof of identification and a signed {PGP} or {GPG} key.
	There are over 400 Debian developers all around the world --
	many developers have never met face-to-face, and most
	development talks take place on the many {mailing lists} and
	the {IRC} network.

	{Home (http://www.debian.org/)}.

	{Debian Linux archives (ftp://ftp.debian.org/debian)}.

	(1999-02-23)

1. {firewall code}.

	2. {firewall machine}.

1. <networking> A computer connected to a {network}.

	The term {node} includes devices such as routers and printers
	which would not normally be called "hosts".

	2. <communications> A computer to which one connects using a
	{terminal emulator}.

	(1995-02-16)

<standard, programming> (CORBA) An {Object Management Group}
	specification which provides a standard messaging interface
	between distributed {objects}.

	The original CORBA specification (1.1) has been revised
	through version 2 (CORBA 2) with the latest specification
	being version 3 (CORBA 3).  In its most basic form CORBA
	consists of the {Interface Definition Language} (IDL) and the
	Dynamic Invocation Interface (DII).

	The IDL definition is complied into a Stub (client) and
	Skeleton (server) component that communicate through an
	{Object Request Broker} (ORB).  When an ORB determines that a
	request is to a remote object, it may execute the request by
	communicating with the remote ORB.

	The Corba IDL can be mapped to a number of languages including
	{C}, {C++}, {Java}, {COBOL}, {Smalltalk}, {Ada}, {Lisp},
	{Python}, and {IDLscript}.  CORBA ORBs are widely available
	for a number of platforms.  The OMG standard for inter-ORB
	communication is {IIOP}, this ensures that all CORBA 2
	compliant ORBS are able to interoperate.

	See also {COSS}, {Component Object Model}, {RMI}.

	{OMG CORBA site (http://www.corba.org/)}.

	(2003-11-21)

Said of something that functions, but in a slightly strange,
	{kluge}y way.  It does the job and would be difficult to
	change, so its obvious non-optimality is left alone.  Often
	used to describe interfaces.  The more bugs something has that
	nobody has bothered to fix because workarounds are easier, the
	funkier it is.  {TECO} and {UUCP} are funky.  The {Intel}
	{i860}'s exception handling is extraordinarily funky.  Most
	standards acquire funkiness as they age.  "The new mailer is
	installed, but is still somewhat funky; if it bounces your
	mail for no reason, try resubmitting it."  "This {UART} is
	pretty funky.  The data ready line is active-high in interrupt
	mode and active-low in {DMA} mode."

	[{Jargon File}]

<data> A data structure holding many values, possibly of
	different types, which is usually accessed sequentially,
	working from the head to the end of the tail - an "ordered
	list".  This contrasts with a (one-dimensional) {array}, any
	element of which can be accessed equally quickly.

	Lists are often stored using a cell and pointer arrangement
	where each value is stored in a cell along with an associated
	pointer to the next cell.  A special pointer, e.g. zero, marks
	the end of the list.  This is known as a (singly) "linked
	list".  A doubly linked list has pointers from each cell to
	both next and previous cells.

	An unordered list is a {set}.

	(1998-11-12)

1. <networking> {e-mail address}.

	2. <networking> {Internet address}.

	3. <networking> {MAC address}.

	4. <storage, programming> An unsigned integer used to select
	one fundamental element of storage, usually known as a {word}
	from a computer's {main memory} or other storage device.  The
	{CPU} outputs addresses on its {address bus} which may be
	connected to an {address decoder}, {cache controller}, {memory
	management unit}, and other devices.

	While from a hardware point of view an address is indeed an
	integer most {strongly typed} programming languages disallow
	mixing integers and addresses, and indeed addresses of
	different data types.  This is a fine example for {syntactic
	salt}: the compiler could work without it but makes writing
	bad programs more difficult.

	(1997-07-01)

<file system> An element of data storage in a {file system}.

	The history of computing is rich in varied kinds of files and
	{file systems}, whether ornate (e.g., {Macintosh file system}
	for a well-known case) or deficient (e.g., many simple
	pre-1980s file systems don't allow {directories}).

	However, the prototypical file has these characteristics:

	* It is a single sequence of bytes (but consider {Macintosh}
	{resource forks}).

	* It has a finite length, unlike, e.g. a {Unix} {device}.

	* It is stored in a {non-volatile storage} medium (but see
	{ramdrive}).

	* It exists (nominally) in a {directory}.

	* It has a name that it can be referred to by in file
	operations, possibly in combination with its {path}.

	Additionally, a file system may associate other information
	with a file, such as {permission} bits or other {file
	attributes}; timestamps for file creation, last revision, and
	last access; revision numbers (a` la VMS), and other kinds of
	{magic}.

	Compare: {document}.

	(1997-04-08)

<software> (Or "option", "flag", "switch", "option switch") An
	argument to a command that modifies its function rather than
	providing data.  Options generally start with "-" in {Unix} or
	"/" in {MS-DOS}.  This is usually followed by a single letter
	or occasionally a digit.

	Some commands require each option to be a separate argument,
	introduced by a new "-" or "/", others allow multiple option
	letters to be concatenated into a single argument with a
	single "-" or "/", e.g. "ls -al".  A few Unix commands
	(e.g. {ar}, {tar}) allow the "-" to be omitted.  Some options
	may or must be followed by a value, e.g. "cc prog.c -o prog",
	sometimes with and sometimes without an intervening space.

	{getopt} and {getopts} are commands for parsing command line
	options.  There is also a {C} library routine called getopt
	for the same purpose.

	(1996-12-11)

<object-oriented> In {object-oriented programming}, an
	instance of the data structure and behaviour defined by the
	object's {class}.  Each object has its own values for the
	{instance variables} of its class and can respond to the
	{methods} defined by its class.

	For example, an object of the "Point" class might have
	instance variables "x" and "y" and might respond to the "plot"
	method by drawing a dot on the screen at those coordinates.

	(2004-01-26)

1. <programming> An {address}, from the point of view of a
	programming language.  A pointer may be typed, with its {type}
	indicating the type of data to which it points.

	The terms "pointer" and "reference" are generally
	interchangable although particular programming languages often
	differentiate these two in subtle ways.  For example, {Perl}
	always calls them references, never pointers.  Conversely, in
	C, "pointer" is used, although "a reference" is often used to
	denote the concept that a pointer implements.

	{Anthony Hoare} once said:

	Pointers are like jumps, leading wildly from one part of the
	data structure to another.  Their introduction into high-level
	languages has been a step backward from which we may never
	recover.

	[C.A.R.Hoare "Hints on Programming Language Design", 1973,
	Prentice-Hall collection of essays and papers by Tony Hoare].

	2. <operating system> (Or "mouse pointer") An {icon}, usually
	a small arrow, that moves on the screen in response to
	movement of a {pointing device}, typically a {mouse}.  The
	pointer shows the user which object on the screen will be
	selected etc. when a mouse button is clicked.

	(1999-07-07)

<protocol> (HTTP) The {client-server} {TCP/IP} {protocol} used
	on the {World-Wide Web} for the exchange of {HTML} documents.
	It conventionally uses {port} 80.

	Current version: HTTP 1.1, defined in {RFC 2068}, as of May
	1997.

	See also {Uniform Resource Locator}.

	(1994-10-27)