<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)

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, library> A collection of {subroutines} and
	{functions} stored in one or more files, usually in compiled
	form, for linking with other programs.  Libraries are one of
	the earliest forms of organised {code reuse}.  They are often
	supplied by the {operating system} or {software development
	environment} developer to be used in many different programs.
	The routines in a library may be general purpose or designed
	for some specific function such as three dimensional animated
	graphics.

	Libraries are linked with the user's program to form a
	complete {executable}.  The linking may be {static linking}
	or, in some systems, {dynamic linking}.

	(1998-11-21)

<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)

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

	See also {dry run}.

	(1996-05-13)

<programming> (Or "computer program", "program", "code") The
	instructions executed by a computer, as opposed to the
	physical device on which they run (the "{hardware}").

	The term was coined by the eminent statistician, {John Tukey}.

	Programs stored on {non-volatile storage} built from
	{integrated circuits} (e.g. {ROM} or {PROM}) are usually
	called {firmware}.

	Software can be split into two main types - {system software}
	and application software or {application programs}.  System
	software is any software required to support the production or
	execution of application programs but which is not specific to
	any particular application.  Examples of system software would
	include the {operating system}, {compilers}, editors and
	sorting programs.

	Examples of application programs would include an accounts
	package or a {CAD} program.  Other broad classes of
	application software include {real-time} software, {business
	software}, scientific and engineering software, {embedded
	software}, personal computer software and {artificial
	intelligence} software.

	Software includes both {source code} written by humans and
	executable {machine code} produced by {assemblers} or
	{compilers}.  It does not usually include the data processed
	by programs unless this is in a format such as {multimedia}
	which depends on the use of computers for its presentation.
	This distinction becomes unclear in cases such as {spread
	sheets} which can contain both instructions (formulae and
	{macros}) and data.  There are also various intermediate
	compiled or {semi-compiled}, forms of software such as
	{library} files and {byte-code}.

	Some claim that {documentation} (both paper and electronic) is
	also software.  Others go further and define software to be
	programs plus documentation though this does not correspond
	with common usage.

	The noun "program" describes a single, complete and
	more-or-less self-contained list of instructions, often stored
	in a single {file}, whereas "code" and "software" are
	uncountable nouns describing some number of instructions which
	may constitute one or more programs or part thereof.  Most
	programs, however, rely heavily on various kinds of {operating
	system} software for their execution.  The nounds "code" and
	"software" both refer to the same thing but "code" tends to
	suggest an interest in the implementation details whereas
	"software" is more of a user's term.

	(2002-07-21)

/de'moh/ 1. A demonstration of a product, often of an early
	version or prototype.  A demo is a far more effective way of
	inducing bugs to manifest themselves than any number of {test}
	runs, especially when important people are watching.

	2. {demo version}.

	3. A program written to demonstrate the programmer's coding
	ability and/or the power of the computer it runs on.  Such
	demos are nearly always written in {machine code} and
	traditionally feature scrolling text about the author, his
	friends, his code and anything else he fancies and animated
	graphics.

	[{Jargon File}]

	(1994-11-04)

<hypertext, World-Wide Web, standard> (HTML) A {hypertext}
	document format used on the {World-Wide Web}.  HTML is built
	on top of {SGML}.  "Tags" are embedded in the text.  A tag
	consists of a "<", a "directive" (in lower case), zero or
	more parameters and a ">".  Matched pairs of directives, like
	"<title>" and "</title>" are used to delimit text which is to
	appear in a special place or style.

	Links to other documents are in the form

	 <a href="http://machine.edu/subdir/file.html">foo</a>

	where "<a>" and "</a>" delimit an "anchor", "href" introduces
	a hypertext reference, which is most often a {Uniform Resource
	Locator} (URL) (the string in double quotes in the example
	above).  The link will be represented in the browser by the
	text "foo" (typically shown underlined and in a different
	colour).

	A certain place within an HTML document can be marked with a
	named anchor, e.g.:

	 <a name="baz">

	The "fragment identifier", "baz", can be used in an href by
	appending "#baz" to the document name.

	Other common tags include <p> for a new paragraph, <b>..</b>
	for bold text, <ul> for an unnumbered list, <pre> for
	preformated text, <h1>, <h2> .. <h6> for headings.

	{HTML} supports some standard {SGML} {national characters} and
	other non-{ASCII} characters through special {escape
	sequences}, e.g. "&eacute;" for a lower case 'e' with an acute
	accent.  You can sometimes get away without the terminating
	semicolon but it's bad style.

	Most systems will ignore the case of tags and attributes but
	lower case should be used for compatibility with {XHTML}.

	The {World-Wide Web Consortium} (W3C) is the international
	{standards} body for HTML.

	Latest version: {XHTML} 1.0, as of 2000-09-10.

	{Home (http://www.w3.org/MarkUp/)}.

	{Character escape sequences
	(http://www.w3.org/hypertext/WWW/MarkUp/ISOlat1.html)}.

	See also {weblint}.

	(2006-01-19)

<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)

1. To prepare to read or write a file.  This usually involves
	checking whether the file already exists and that the user has
	the necessary authorisation to read or write it.  The result
	of a successful open is usually some kind of {capability}
	(e.g. a {Unix} {file descriptor}) - a token that the user
	passes back to the system in order to access the file without
	further checks and finally to close the file.

	2. Abbreviation for "open (or left) parenthesis" - used when
	necessary to eliminate oral ambiguity.  To read aloud the LISP
	form (DEFUN FOO (X) (PLUS X 1)) one might say: "Open defun
	foo, open eks close, open, plus eks one, close close."

	3. Non-proprietary.  An open {standard} is one which can be
	used without payment.

	[{Jargon File}]

	(1995-01-31)

<World-Wide Web> A complete {free}, {open-source} {web
	browser} from the {Mozilla Foundation} and therefore a true
	code descendent of {Netscape Navigator}.  The first non-{beta
	release} was in late 2004.

	{Firefox Home (http://www.mozilla.org/products/firefox)}.

	(2005-01-26)

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)

1. The operator's station of a {mainframe}.  In times past,
	this was a privileged location that conveyed godlike powers to
	anyone with fingers on its keys.  Under {Unix} and other
	modern {time-sharing} {operating systems}, such privileges are
	guarded by passwords instead, and the console is just the
	{tty} the system was booted from.  Some of the mystique
	remains, however, and it is traditional for {sysadmins} to
	post urgent messages to all users from the console (on Unix,
	/dev/console).

	2. On {microcomputer} {Unix} boxes, the main screen and
	keyboard (as opposed to character-only terminals talking to a
	{serial port}).  Typically only the console can do real
	graphics or run {X}.  See also {CTY}.

	[{Jargon File}]

1. <mathematics> (Or "map", "mapping") If D and C are sets
	(the domain and codomain) then a function f from D to C,
	normally written "f : D -> C" is a subset of D x C such that:

	1. For each d in D there exists some c in C such that (d,c) is
	an element of f.  I.e. the function is defined for every
	element of D.

	2. For each d in D, c1 and c2 in C, if both (d,c1) and (d,c2)
	are elements of f then c1 = c2.  I.e. the function is uniquely
	defined for every element of D.

	See also {image}, {inverse}, {partial function}.

	2. <programming> Computing usage derives from the mathematical
	term but is much less strict.  In programming (except in
	{functional programming}), a function may return different
	values each time it is called with the same argument values
	and may have {side effects}.

	A {procedure} is a function which returns no value but has
	only {side-effects}.  The {C} language, for example, has no
	procedures, only functions.  {ANSI C} even defines a {type},
	{void}, for the result of a function that has no result.

	(1996-09-01)

<language> ({ECMA} standard 262, {ISO} standard 16262) The
	standardised version of the core {JavaScript} language.

	(2005-07-28)

<language, programming> (Or "source", or rarely "source
	language") The form in which a computer program is written by
	the programmer.  Source code is written in some formal
	programming language which can be compiled automatically into
	{object code} or {machine code} or executed by an
	{interpreter}.

	(1995-01-05)

<language> A language compatible with the language
	{Dylan}(TM).  Thomas is NOT {Dylan}(TM).

	The first public release of a translator to {Scheme} by Matt
	Birkholz, Jim Miller, and Ron Weiss, written at {Digital
	Equipment Corporation}'s {Cambridge Research Laboratory} runs
	(slowly) on {MIT}'s {CScheme}, DEC's {Scheme->C}, Marc
	Feeley's {Gambi}, {Macintosh}, {PC}, {Vax}, {MIPS}, {Alpha},
	{680x0}.

	{(ftp://gatekeeper.pa.dec.com/pub/DEC/Thomas)}.

	Mailing list: <info-thomas@crl.dec.com>.

	["Dylan(TM) an object-oriented dynamic language", {Apple
	Computer}, Eastern Research and Technology, April 1992].

	(1992-09-11)

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)

<World-Wide Web> (URI, originally "UDI" in some {WWW}
	documents) The generic set of all names and addresses which
	are short strings which refer to objects (typically on the
	{Internet}).  The most common kinds of URI are {URLs} and
	{relative URLs}.

	URIs are defined in {RFC 1630}.

	{W3 specification
	(http://www.w3.org/hypertext/WWW/Addressing/URL/URI_Overview.html)}.

	(1997-07-16)

<jargon, programming> A temporary {kluge} used to bypass, mask
	or otherwise avoid a {bug} or {misfeature} in some system.
	Customers often find themselves living with workarounds for
	long periods of time rather than getting a {bug fix}.

	[{Jargon File}]

	(1998-06-25)

<programming> One of a sequence of copies of a program, each
	incorporating new modifications.  Each version is usually
	identified by a number, commonly of the form X.Y where X is
	the major version number and Y is the release number.
	Typically an increment in X (with Y reset to zero) signifies a
	substantial increase in the function of the program or a
	partial or total re-implementation, whereas Y increases each
	time the progam is changed in any way and re-released.

	Version numbers are useful so that the user can know if the
	program has changed ({bugs} have been fixed or new functions
	added) since he obtained his copy and the programmer can tell
	if a bug report relates to the current version.  It is thus
	always important to state the version when reporting bugs.
	Statements about compatibility between different software
	components should always say which versions they apply to.

	See {change management}.

	(1997-12-07)

<company> The biggest supplier of {operating systems} and
	other software for {IBM PC} compatibles.  Software products
	include {MS-DOS}, {Microsoft Windows}, {Windows NT},
	{Microsoft Access}, {LAN Manager}, {MS Client}, {SQL Server},
	{Open Data Base Connectivity} (ODBC), {MS Mail}, and {SNA
	Server} for Windows NT.

	Microsoft was founded as "Micro-soft" in 1975 by {Bill Gates}
	(now CEO) and his high school pal Paul Allen.  Their first
	product was a version of {BASIC} for the new {Altair} computer
	[which one?].  In 1980, {IBM} chose Microsoft to supply the
	{operating system} for the {IBM PC}.

	On the UK television program "The Net" in May 1994, {Bill
	Gates} said he was betting his company on the {information
	highway}".

	Quarterly sales $1293M, profits $362M (Aug 1994).

	{Home (http://www.microsoft.com/)}.
	{(ftp://ftp.microsoft.com/)}.

	{Interesting Info and Other Microsoft WWW Servers
	(http://www-drg.microsoft.com/devinfo.htm)}.

	{Microsoft Windows Developer Information
	(http://www-drg.microsoft.com/devinfo.htm)}.

	{Microsoft Research Group Information
	(http://www.research.microsoft.com)}.

	{Win_News
	(http://www.microsoft.com/chicago/ms-www/ms-intro.htm)}.
	maintained by the Personal Operating Systems Division to
	distribute information on {Microsoft Windows}, {MS-DOS} and
	{Windows 95}.

	(1998-11-06)