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)

<operating system> See {Microsoft Windows}, {Windows NT}.

	(1997-11-23)

<language, text> An {SGML}, {HTML}, or {XML} {token}
	representing the beginning (start tag: "<p ...>") or end (end
	tag: "</p>") of an {element}.  In normal SGML {syntax} (and
	always in {XML}), a tag starts with a "<" and ends with an
	">".

	In {HTML} jargon, the term "tag" is often used for an
	"{element}".

	(2001-01-31)

<software> Instructions for a computer in some programming
	language, often {machine language}.  The word "code" is often
	used to distinguish instructions from {data} (e.g. "The code
	is marked 'read-only'") whereas "{software}" is used in
	contrast with "{hardware}" and may consist of more than just
	code.

	(2000-04-08)

<operating system> A {directory} in the sense of a collection
	of computer {files}.  The term is more common in systems such
	as the {Macintosh} or {Windows 95} which have a {graphical
	user interface} and provide a graphical {file browser} in
	which directories are traditionally depicted as folders (like
	small briefcases).

	(1997-03-20)

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)

<networking> Name Daemon.

	<networking> A {Unix} {background} process that converts
	{hostnames} to {Internet addresses} for the {TCP/IP}
	{protocol}.

	{Unix manual page}: named(8).

	See also {DNS}.

	(1995-03-28)

<World-Wide Web, database, tool> {Allaire Corporation}'s
	commercial {database} application development tool that allows
	{databases} to have a {World-Wide Web} {interface}, so a
	database can be queried and updated using a {web browser}.

	The ColdFusion Server application runs on the {web server} and
	has access to a {database}.  ColdFusion files on the web
	server are {HTML} pages with additional ColdFusion commands to
	{query} or {update} the database, written in {CFML}.  When the
	page is requested by the user, the {web server} passes the
	page to the Cold Fusion application, which executes the {CFML}
	commands, places the results of the {CFML} commands in the
	{HTML} file, and returns the page to the {web server}.  The
	page returned to the {web server} is now an ordinary {HTML}
	file, and it is sent to the user.

	Examples of ColdFusion applications include order entry, event
	registration, catalogue search, directories, calendars, and
	interactive training.  ColdFusion applications are robust
	because all database interactions are encapsulated in a single
	industrial-strength {CGI} script.  The formatting and
	presentation can be modified and revised at any time (as
	opposed to having to edit and recompile {source code}).

	ColdFusion Server can connect with any database that supports
	{ODBC} or {OLE DB} or one that has a native database driver.
	Native database drivers are available for {Oracle} and
	{Sybase} databases.

	ColdFusion is available for {Windows}, {Solaris}, and {HP-UX}.
	A {development environment} for creating ColdFusion files,
	called ColdFusion Studio, is also available for {Windows}.

	Current version: MX(6), as of 2003-07-11.

	The {filename extension} for ColdFusion files is .cfm

	{Home (http://www.coldfusion.com/)}.

	(2003-07-27)

An error condition that changes the normal {flow of control}
	in a program.  An exception may be generated ("raised") by
	{hardware} or {software}.  Hardware exceptions include
	{reset}, {interrupt} or a signal from a {memory management
	unit}.  Exceptions may be generated by the {arithmetic logic
	unit} or {floating-point unit} for numerical errors such as
	divide by zero, {overflow} or {underflow} or {instruction
	decoding} errors such as privileged, reserved, {trap} or
	undefined instructions.  Software exceptions are even more
	varied and the term could be applied to any kind of error
	checking which alters the normal behaviour of the program.

	(1994-10-31)

<networking, programming> Work performed (or offered) by a
	{server}.  This may mean simply serving simple requests for
	data to be sent or stored (as with {file servers}, {gopher} or
	{http} servers, {e-mail} servers, {finger} servers, {SQL}
	servers, etc.); or it may be more complex work, such as that
	of {irc} servers, print servers, {X Windows} servers, or
	process servers.

	E.g. "Access to the finger {service} is restricted to the
	local {subnet}, for security reasons".

	(1997-09-11)

1. <application, algorithm> To arrange a collection of items
	in some specified order.  The items - {records} in a file or
	data structures in memory - consist of one or more {fields} or
	members.  One of these fields is designated as the "sort key"
	which means the records will be ordered according to the value
	of that field.  Sometimes a sequence of key fields is
	specified such that if all earlier keys are equal then the
	later keys will be compared.  Within each field some ordering
	is imposed, e.g. ascending or descending numerical, {lexical
	ordering}, or date.

	Sorting is the subject of a great deal of study since it is a
	common operation which can consume a lot of computer time.
	There are many well-known sorting {algorithms} with different
	time and space behaviour and programming {complexity}.

	Examples are {quicksort}, {insertion sort}, {bubble sort},
	{heap sort}, and {tree sort}.  These employ many different
	data structures to store sorted data, such as {arrays},
	{linked lists}, and {binary trees}.

	2. <tool> The {Unix} utility program for sorting lines of
	files.

	{Unix manual page}: sort(1).

	(1997-02-12)

<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)

<text, tool> The very basic {text editor} supplied with
	{Microsoft Windows}.

	(1998-01-05)

<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. The {supervisor} program or {operating system} on a
	computer.

	2. The entire computer system, including input/output devices,
	the {supervisor} program or {operating system} and possibly
	other {software}.

	3. Any large program.

	4. Any method or {algorithm}.

	[{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> A {functional programming} language designed by
	R.M. Burstall, D.B. MacQueen and D.T. Sanella at {University
	of Edinburgh} in 1978.  It is a large language supporting
	user-defined {prefix}, {infix} or {distfix} operators.  Hope
	has {polymorphic} typing and allows {overloading} of operators
	which requires explicit type declarations.  Hope has {lazy
	lists} and was the first language to use {call-by-pattern}.

	It has been ported to {Unix}, {Macintosh}, and {IBM PC}.

	See also {Hope+}, {Hope+C}, {Massey Hope}, {Concurrent Massey
	Hope}.

	{(ftp://brolga.cc.uq.oz.au/pub/hope)}.

	[R.M.Burstall, D.B.MacQueen, D.T.Sanella, "HOPE: An
	experimental applicative language", Proc. 1980 Lisp conf.,
	Stanford, CA, p.136-143, Aug 1980].

	["A HOPE Tutorial", R. Bailey, BYTE Aug 1985, pp.235-258].

	["Functional Programming with Hope", R. Bailey, Ellis Horwood
	1990].

	(1992-11-27)