Transient (computer programming)
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In
computer programming Computer programming or coding is the composition of sequences of instructions, called computer program, programs, that computers can follow to perform tasks. It involves designing and implementing algorithms, step-by-step specifications of proc ...
, 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 In product development, an end user (sometimes end-user) is a person who ultimately uses or is intended to ultimately use a product. The end user stands in contrast to users who support or maintain the product, such as sysops, system administrato ...
which is displayed with a transient application posture; ''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 (also procedure, method, subroutine, routine, or subprogram) is a callable unit of software logic that has a well-defined interface and behavior and can be invoked multiple times. Callable units provide a ...
s or
software component A software component is a modular unit of software that encapsulates specific functionality. The desired characteristics of a component are reusability and maintainability. Value Components allow software development to assemble software ...
s 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 Java is a high-level, general-purpose, memory-safe, object-oriented programming language. It is intended to let programmers ''write once, run anywhere'' ( WORA), meaning that compiled Java code can run on all platforms that support Jav ...
, transient is a keyword 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 reduction entered by some animal species. Hibernation is a seasonal heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate. It is 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 originated as part of Project Athena at Massachusetts Institute of Technology (MIT) in 1984. The X protocol has been at ...
, 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 In computing, a dialog box (also simply dialog) is a graphical control element in the form of a small window that communicates information to the user and prompts them for a response. Dialog boxes are classified as " modal" or "modeless", dep ...
, 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 A window manager is system software that controls the placement and appearance of window (computing), windows within a windowing system in a graphical user interface. Most window managers are designed to help provide a desktop environment. They ...
, and unlike top-level windows (which can require user placement, as in
twm twm (Tab Window Manager) is a 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 Window Manager, but ...
), 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 remembe ...
, is expected to remain in memory for a short time. Today, the term is rarely used, and may be obsolete. The term Overlay 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 announced by IBM on April 7, 1964, and delivered between 1965 and 1978. System/360 was the first family of computers designed to cover both commercial and scientific applicati ...
, 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 Out of memory (OOM) is an often undesired state of computer operation where no additional memory can be allocated for use by programs or the operating system. Such a system will be unable to load any additional programs, and since many programs ...
. 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 o ...
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 The IBM 1130 Computing System, introduced in 1965, was IBM's least expensive computer at that time. A binary 16-bit machine, it was marketed to price-sensitive, computing-intensive technical markets, like education and engineering, succeeding th ...
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 op ...
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 ...
, 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