Transient (computer programming)
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In
computer programming Computer programming is the process of performing a particular computation (or more generally, accomplishing a specific computing result), usually by designing and building an executable computer program. Programming involves tasks such as ana ...
, transient is a property of any element in the system that is temporary. The term applies to '' transient applications'', i.e. software for the end-user which is displayed with a transient
application posture The term application posture characterizes the nature of a software application's interaction with its user. The term was coined by Alan Cooper, who characterized four 'postures' for applications: sovereign, transient, daemonic and parasitic. * A ...
; ''transient data'', which is discarded after it is no longer needed by the computation; and ''transient code'' which are
subroutine In computer programming, a function or subroutine is a sequence of program instructions that performs a specific task, packaged as a unit. This unit can then be used in programs wherever that particular task should be performed. Functions may ...
s or software components that are loaded in the system only for a fraction of the total run time. Examples of applications of the term are described below.


Java

In the Java programming language, transient is a
keyword Keyword may refer to: Computing * Keyword (Internet search), a word or phrase typically used by bloggers or online content creator to rank a web page on a particular topic * Index term, a term used as a keyword to documents in an information syste ...
used as a field modifier. When a field is declared transient, it would not be serialized even if the class to which it belongs is serialized. In Java, methods, classes and interfaces cannot be declared as transient, because they are never serialized. In
Hibernate Hibernation is a state of minimal activity and metabolic depression undergone by some animal species. Hibernation is a seasonal heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate. It most ...
and other persistence systems, ''transient'' describes an object that has been instantiated, but is not associated with a Hibernate session, i. e. the object resides in memory but is not being persisted.


X

In the
X Window System The X Window System (X11, or simply X) is a windowing system for bitmap displays, common on Unix-like operating systems. X provides the basic framework for a GUI environment: drawing and moving windows on the display device and interacting wit ...
, a window is said to be transient ''for'' another window if it belongs to that other window and may not outlast it: a dialog box, such as an alert message, is a common example. This should not be confused with a window containing another window: contained windows lie entirely within their parents, but transients are separate windows which can generally be moved freely around the screen. Transient windows may be treated specially by the window manager, and unlike top-level windows (which can require user placement, as in
twm twm (Tab Window Manager) is a X window manager, window manager for the X Window System. Started in 1987 by Tom LaStrange, it has been the standard window manager for the X Window System since version X11R4. The name originally stood for Tom's Wi ...
), must never require any user interaction on appearing.


Operating systems

''Transient'' also refers to a module that, once loaded into main
memory Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered, ...
, is expected to remain in memory for a short time. Today, the term is rarely used, and may be obsolete. The term
Overlay Overlay may refer to: Computers *Overlay network, a computer network which is built on top of another network *Hardware overlay, one type of video overlay that uses memory dedicated to the application *Another term for exec, replacing one process ...
is commonly used instead, and refer to a program module that is brought to memory when it is needed by the running program and then replaced with another when it is no longer needed, so a program had lower memory requirements. Program modules were written to allow different modules to share the same memory region and the main program itself was responsible of exchanging modules between disk and memory as necessary. In the mid-to-late 1960s, mainframe computers, such as the
IBM System/360 The IBM System/360 (S/360) is a family of mainframe computer systems that was announced by IBM on April 7, 1964, and delivered between 1965 and 1978. It was the first family of computers designed to cover both commercial and scientific applica ...
, had memory sizes from 8 KB to 512 KB. In order to conserve memory, transients were small modules that supported a specific task, and were swapped in and out of memory. The concept of transient area is part of Mythical Man-Month's discussion on design and the use of main memory. The operating system for the S/360 had two areas reserved for
transients Transience or transient may refer to: Music * ''Transient'' (album), a 2004 album by Gaelle * ''Transience'' (Steven Wilson album), 2015 * Transience (Wreckless Eric album) Science and engineering * Transient state, when a process variable or ...
that supported input/output operations. These were referred to as the "logical transient area" and the "physical transient area." If an application program, for example, needed to use the printer, transients that supported printing were brought into the transient areas. If an application needed to use tape drives, transients that supported tape drive access were brought into the transient areas. The IBM 1130 of the same era used part of the first 4K of memory as a transient area. In the 1980s,
MS-DOS MS-DOS ( ; acronym for Microsoft Disk Operating System, also known as Microsoft DOS) is an operating system for x86-based personal computers mostly developed by Microsoft. Collectively, MS-DOS, its rebranding as IBM PC DOS, and a few ope ...
reloaded the transient portion of COMMAND.COM between programs or user commands.


Message passing

At the level of
message passing In computer science, message passing is a technique for invoking behavior (i.e., running a program) on a computer. The invoking program sends a message to a process (which may be an actor or object) and relies on that process and its supporting i ...
, transient communication means the way by which the messages are not saved into a buffer to wait for its delivery at the message receiver. The messages will be delivered ''only'' if both the systems (sender and receiver) are running. If the receiver is not running at the send time, the message will be discarded, because it has not been stored into intermediate buffers.


References

{{DEFAULTSORT:Transient (Computer Programming) Computer programming X Window System sv:Transient