<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)

1. {application program}.

	2. {function application}.

<language> One of the most used {object-oriented} languages, a
	superset of {C} developed primarily by {Bjarne Stroustrup}
	<bs@alice.att.com> at {AT&T} {Bell Laboratories} in 1986.

	In C++ a {class} is a user-defined {type}, syntactically a
	{struct} with {member functions}.  {Constructors} and
	{destructors} are member functions called to create or destroy
	{instances}.  A {friend} is a nonmember function that is
	allowed to access the private portion of a class.  C++ allows
	{implicit type conversion}, {function inlining}, {overloading}
	of operators and function names, and {default function
	arguments}.  It has {streams} for I/O and {references}.

	C++ 2.0 (May 1989) introduced {multiple inheritance},
	{type-safe linkage}, pointers to members, and {abstract
	classes}.

	C++ 2.1 was introduced in ["Annotated C++ Reference Manual",
	B. Stroustrup et al, A-W 1990].

	{MS-DOS
	(ftp://grape.ecs.clarkson.edu/pub/msdos/djgpp/djgpp.zip)},
	{Unix ANSI C++
	(ftp://gnu.org/pub/gnu/g++-1.39.0.tar.Z)} - X3J16
	committee. (They're workin' on it).

	See also {cfront}, {LEDA}, {uC++}.

	{Usenet} newsgroup: {news:comp.lang.c++}.

	["The C++ Programming Language", Bjarne Stroustrup, A-W,
	1986].

	(1996-06-06)

1. <language> {Synthesizer Specification Language}.

	2. <language> {Syntax/Semantic Language} (S/SL).

	3. <networking, World-Wide Web> {Secure Sockets Layer}.

	(1996-09-08)

<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)

1. <database> A value used to identify a {record} in a
	database, derived by applying some fixed function to the
	record.  The key is often simply one of the {fields} (a
	{column} if the database is considered as a table with records
	being rows, see "{key field}").  Alternatively the key may be
	obtained by applying some function, e.g. a {hash function}, to
	one or more of the fields.  The set of keys for all records
	forms an {index}.  Multiple indexes may be built for one
	database depending on how it is to be searched.

	2. <cryptography> A value which must be fed into the
	{algorithm} used to decode an encrypted message in order to
	reproduce the original {plain text}.  Some encryption schemes
	use the same (secret) key to encrypt and decrypt a message,
	but {public key encryption} uses a "private" (secret) key and
	a "public" key which is known by all parties.

	3. <hardware> An electromechanical {keyboard} button.

	(2003-07-04)

1. <programming, operating system> A simple item of data that
	identifies a resource.  For example, a {Unix} file handle
	identifies an open file and associated data such as whether it
	was opened for read or write and the current read/write
	position.  On the {Macintosh}, a handle is a pointer to a
	pointer to some dynamically-allocated memory.  The extra level
	of indirection allows on-the-fly {memory compaction} or
	{garbage collection} without invalidating application program
	references to the allocated memory.

	2. <jargon> An alias used intended to conceal a user's true
	identity in an electronic message.  The term is common on
	Citizen's Band and other amateur radio but, in that context
	usually means the user's real name as {FCC} rules forbid
	concealing one's identity.

	Use of grandiose handles is characteristic of {crackers},
	{weenies}, {spods}, and other lower forms of network life;
	true hackers travel on their own reputations.

	Compare {nick}.

	[{Jargon File}]

	(2004-07-20)

<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)

<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)

1. <hardware> An electrical conductor.  For distances larger
	than a breadbox, a single line may consist of two electrical
	conductors in twisted, parallel, or concentric arrangement
	used to transport one logical signal.

	By extension, a (usually physical) medium such as an {optical
	fibre} which carries a signal.

	(1995-09-29)

<protocol, standard> (IIOP) A protocol which will be mandatory
	for all {CORBA} 2.0 compliant {platforms}.  The initial phase
	of the project is to build an infrastructure consisting of: an
	IIOP to {HTTP} {gateway} which allows CORBA {clients} to
	access {WWW} resources; an HTTP to IIOP gateway to let WWW
	clients access CORBA resources; a {web server} which makes
	resources available by both IIOP and HTTP; web browsers which
	can use IIOP as their {native} protocol.

	{Home (http://www.ansa.co.uk/ANSA/ISF/wwwCorba_1.html)}.

	(1996-04-01)

<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)

A collection of objects, known as the elements of the set,
	specified in such a way that we can tell in principle whether
	or not a given object belongs to it.  E.g. the set of all prime
	numbers, the set of zeros of the cosine function.

	For each set there is a {predicate} (or property) which is
	true for (possessed by) exactly those objects which are
	elements of the set.  The predicate may be defined by the set
	or vice versa.  Order and repetition of elements within the
	set are irrelevant so, for example, {1, 2, 3} = {3, 2, 1} =
	{1, 3, 1, 2, 2}.

	Some common set of numbers are given the following names:

	N = the {natural numbers} 0, 1, 2, ...

	Z = the {integers} ..., -2, -1, 0, 1, 2, ...

	Q = the {rational numbers} p/q where p, q are in Z and q /= 0.

	R = the {real numbers}

	C = the {complex numbers}.

	The empty set is the set with no elements.  The intersection
	of two sets X and Y is the set containing all the elements x
	such that x is in X and x is in Y.  The union of two sets is
	the set containing all the elements x such that x is in X or x
	is in Y.

	See also {set complement}.

	(1995-01-24)

<language, compiler> (JDK) A free {Sun Microsystems} product
	which provides the {environment} required for programming in
	{Java}.  The JDK is available for a variety of {platforms},
	but most notably {Sun Solaris} and {Microsoft Windows}.

	{Home (http://java.sun.com/products/jdk/1.1/index.html)}.

	[Version?]

	(1997-09-04)

See {followup}.

<programming> An unwanted and unintended property of a program
	or piece of hardware, especially one that causes it to
	malfunction.  Antonym of {feature}.  E.g. "There's a bug in
	the editor: it writes things out backward."  The
	identification and removal of bugs in a program is called
	"{debugging}".

	Admiral {Grace Hopper} (an early computing pioneer better
	known for inventing {COBOL}) liked to tell a story in which a
	technician solved a {glitch} in the {Harvard Mark II machine}
	by pulling an actual insect out from between the contacts of
	one of its relays, and she subsequently promulgated {bug} in
	its hackish sense as a joke about the incident (though, as she
	was careful to admit, she was not there when it happened).
	For many years the logbook associated with the incident and
	the actual bug in question (a moth) sat in a display case at
	the Naval Surface Warfare Center (NSWC).  The entire story,
	with a picture of the logbook and the moth taped into it, is
	recorded in the "Annals of the History of Computing", Vol. 3,
	No. 3 (July 1981), pp. 285--286.

	The text of the log entry (from September 9, 1947), reads
	"1545 Relay #70 Panel F (moth) in relay.  First actual case of
	bug being found".  This wording establishes that the term was
	already in use at the time in its current specific sense - and
	Hopper herself reports that the term "bug" was regularly
	applied to problems in radar electronics during WWII.

	Indeed, the use of "bug" to mean an industrial defect was
	already established in Thomas Edison's time, and a more
	specific and rather modern use can be found in an electrical
	handbook from 1896 ("Hawkin's New Catechism of Electricity",
	Theo. Audel & Co.)  which says: "The term "bug" is used to a
	limited extent to designate any fault or trouble in the
	connections or working of electric apparatus."  It further
	notes that the term is "said to have originated in
	{quadruplex} telegraphy and have been transferred to all
	electric apparatus."

	The latter observation may explain a common folk etymology of
	the term; that it came from telephone company usage, in which
	"bugs in a telephone cable" were blamed for noisy lines.
	Though this derivation seems to be mistaken, it may well be a
	distorted memory of a joke first current among *telegraph*
	operators more than a century ago!

	Actually, use of "bug" in the general sense of a disruptive
	event goes back to Shakespeare!  In the first edition of
	Samuel Johnson's dictionary one meaning of "bug" is "A
	frightful object; a walking spectre"; this is traced to
	"bugbear", a Welsh term for a variety of mythological monster
	which (to complete the circle) has recently been reintroduced
	into the popular lexicon through fantasy {role-playing games}.

	In any case, in jargon the word almost never refers to
	insects.  Here is a plausible conversation that never actually
	happened:

	"There is a bug in this ant farm!"

	"What do you mean?  I don't see any ants in it."

	"That's the bug."

	[There has been a widespread myth that the original bug was
	moved to the Smithsonian, and an earlier version of this entry
	so asserted.  A correspondent who thought to check discovered
	that the bug was not there.  While investigating this in late
	1990, your editor discovered that the NSWC still had the bug,
	but had unsuccessfully tried to get the Smithsonian to accept
	it - and that the present curator of their History of
	American Technology Museum didn't know this and agreed that it
	would make a worthwhile exhibit.  It was moved to the
	Smithsonian in mid-1991, but due to space and money
	constraints has not yet been exhibited.  Thus, the process of
	investigating the original-computer-bug bug fixed it in an
	entirely unexpected way, by making the myth true!  - ESR]

	[{Jargon File}]

	(1999-06-29)

<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. <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)

1. {Advanced Computing Environment}.

	2. {Adaptive Communication Environment}.

<language> 1. A {Lisp} dialect with {concurrency},
	{object-orientation} and logic.

	["Concurrent Programming in TAO - Practice and Experience",
	I. Takeuchi in Parallel Lisp: Languages and Systems, T. Ito et
	al eds, LNCS 441, Springer 1989, pp. 271-299].

	(2006-02-06)

	2. A programming language for {APE/Quadrics} {parallel}
	computers, largely modelled on {FORTRAN} and evolved from the
	even more primitive {APESE} language.  TAO is particularly
	hard to work with, due to the lack of systematics, poor
	documentation and a primitive compiler.

	[Reference?  Dates?]

	(2006-02-06)