Transient (computer programming)

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In computer programming, 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; transient data, which is discarded after it is no longer needed by the computation; and transient code which are subroutines or software components that are loaded in the system only for a fraction of the total run time.

Contents

Examples of applications of the term are described below.

Java

In the Java programming language, 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. [1]

In Hibernate 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. [2]

X

A dialog box is an example of a transient window. Dialog1.png
A dialog box is an example of a transient window.

In the X Window System, 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), must never require any user interaction on appearing. [3]

Operating systems

Transient also refers to a module that, once loaded into main memory, 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. [4]

In the mid-to-late 1960s, mainframe computers, such as the IBM System/360, 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. [5] The operating system for the S/360 had two areas reserved for transients that supported input/output operations. These were referred to as the "logical transient area" [6] and the "physical transient area." [7] 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 reloaded the transient portion of COMMAND.COM between programs or user commands. [8] [9]

Message passing

At the level of message passing, 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.

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<span class="mw-page-title-main">BIOS</span> Firmware for hardware initialization and OS runtime services

In computing, BIOS is firmware used to provide runtime services for operating systems and programs and to perform hardware initialization during the booting process. The BIOS firmware comes pre-installed on an IBM PC or IBM PC compatible's system board and exists in some UEFI-based systems too as a compatibly support module to maintain compatibility operating systems that do not support UEFI native operation. The name originates from the Basic Input/Output System used in the CP/M operating system in 1975. The BIOS originally proprietary to the IBM PC has been reverse engineered by some companies looking to create compatible systems. The interface of that original system serves as a de facto standard.

In computing, serialization is the process of translating a data structure or object state into a format that can be stored or transmitted and reconstructed later. When the resulting series of bits is reread according to the serialization format, it can be used to create a semantically identical clone of the original object. For many complex objects, such as those that make extensive use of references, this process is not straightforward. Serialization of object-oriented objects does not include any of their associated methods with which they were previously linked.

<span class="mw-page-title-main">Transaction Processing Facility</span> IBM real-time operating system

Transaction Processing Facility (TPF) is an IBM real-time operating system for mainframe computers descended from the IBM System/360 family, including zSeries and System z9.

<span class="mw-page-title-main">CP/M</span> Discontinued family of computer operating systems

CP/M, originally standing for Control Program/Monitor and later Control Program for Microcomputers, is a mass-market operating system created in 1974 for Intel 8080/85-based microcomputers by Gary Kildall of Digital Research, Inc. Initially confined to single-tasking on 8-bit processors and no more than 64 kilobytes of memory, later versions of CP/M added multi-user variations and were migrated to 16-bit processors.

<span class="mw-page-title-main">IBM PC compatible</span> Computers similar to the IBM PC and its derivatives

IBM PC compatible computers are similar to the original IBM PC, XT, and AT, all from computer giant IBM, that are able to use the same software and expansion cards. Such computers were referred to as PC clones, IBM clones or IBM PC clones. The term "IBM PC compatible" is now a historical description only, since IBM no longer sells personal computers after it sold its personal computer division in 2005 to Chinese technology company Lenovo. The designation "PC", as used in much of personal computer history, has not meant "personal computer" generally, but rather an x86 computer capable of running the same software that a contemporary IBM PC could. The term was initially in contrast to the variety of home computer systems available in the early 1980s, such as the Apple II, TRS-80, and Commodore 64. Later, the term was primarily used in contrast to Apple's Macintosh computers.

Bytecode is a form of instruction set designed for efficient execution by a software interpreter. Unlike human-readable source code, bytecodes are compact numeric codes, constants, and references that encode the result of compiler parsing and performing semantic analysis of things like type, scope, and nesting depths of program objects.

A blitter is a circuit, sometimes as a coprocessor or a logic block on a microprocessor, dedicated to the rapid movement and modification of data within a computer's memory. A blitter can copy large quantities of data from one memory area to another relatively quickly, and in parallel with the CPU, while freeing up the CPU's more complex capabilities for other operations. A typical use for a blitter is the movement of a bitmap, such as windows and fonts in a graphical user interface or images and backgrounds in a 2D video game. The name comes from the bit blit operation of the 1973 Xerox Alto, which stands for bit-block transfer. A blit operation is more than a memory copy, because it can involve data that's not byte aligned, handling transparent pixels, and various ways of combining the source and destination data.

<span class="mw-page-title-main">Conventional memory</span> First 640K of RAM under DOS

In DOS memory management, conventional memory, also called base memory, is the first 640 kilobytes of the memory on IBM PC or compatible systems. It is the read-write memory directly addressable by the processor for use by the operating system and application programs. As memory prices rapidly declined, this design decision became a limitation in the use of large memory capacities until the introduction of operating systems and processors that made it irrelevant.

In computer systems a loader is the part of an operating system that is responsible for loading programs and libraries. It is one of the essential stages in the process of starting a program, as it places programs into memory and prepares them for execution. Loading a program involves memory-mapping the contents of the executable file containing the program instructions into memory, and then carrying out other required preparatory tasks to prepare the executable for running. Once loading is complete, the operating system starts the program by passing control to the loaded program code.

<span class="mw-page-title-main">IBM TopView</span> Former front-end to DOS

TopView is the first object-oriented, multitasking, and windowing, personal computer operating environment for PC DOS developed by IBM, announced in August 1984 and shipped in March 1985. TopView provided a text-mode operating environment that allowed users to run more than one application at the same time on a PC. IBM demonstrated an early version of the product to key customers before making it generally available, around the time they shipped their new PC AT computer.

Disk Operating System/360, also DOS/360, or simply DOS, is the discontinued first member of a sequence of operating systems for IBM System/360, System/370 and later mainframes. It was announced by IBM on the last day of 1964, and it was first delivered in June 1966. In its time, DOS/360 was the most widely used operating system in the world.

<span class="mw-page-title-main">Rainbow 100</span> DEC microcomputer

The Rainbow 100 is a microcomputer introduced by Digital Equipment Corporation (DEC) in 1982. This desktop unit had a monitor similar to the VT220 and a dual-CPU box with both 4 MHz Zilog Z80 and 4.81 MHz Intel 8088 CPUs. The Rainbow 100 was a triple-use machine: VT100 mode, 8-bit CP/M mode, and CP/M-86 or MS-DOS mode using the 8088.

<span class="mw-page-title-main">Upper memory area</span>

In DOS memory management, the upper memory area (UMA) refers to memory between the addresses of 640 KB and 1024 KB (0xA0000–0xFFFFF) in an IBM PC or compatible. IBM reserved the uppermost 384 KB of the 8088 CPU's 1024 KB address space for BIOS ROM, Video BIOS, Option ROMs, video RAM, RAM on peripherals, memory-mapped I/O, and obsoleted ROM BASIC.

In computer science, marshalling or marshaling is the process of transforming the memory representation of an object into a data format suitable for storage or transmission. It is typically used when data must be moved between different parts of a computer program or from one program to another.

In Unix-like operating systems, a device file or special file is an interface to a device driver that appears in a file system as if it were an ordinary file. There are also special files in DOS, OS/2, and Windows. These special files allow an application program to interact with a device by using its device driver via standard input/output system calls. Using standard system calls simplifies many programming tasks, and leads to consistent user-space I/O mechanisms regardless of device features and functions.

<span class="mw-page-title-main">MS-DOS</span> Microsofts discontinued operating system

MS-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 operating systems attempting to be compatible with MS-DOS, are sometimes referred to as "DOS". MS-DOS was the main operating system for IBM PC compatibles during the 1980s, from which point it was gradually superseded by operating systems offering a graphical user interface (GUI), in various generations of the graphical Microsoft Windows operating system.

<span class="mw-page-title-main">DOS</span> Group of closely related IBM PC-compatible operating systems

DOS is a platform-independent acronym for "disk operating system" that later became a common shorthand for disk-based operating systems on IBM PC compatibles. DOS primarily consists of Microsoft's MS-DOS and a rebranded version under the name IBM PC DOS, both of which were introduced in 1981. Later compatible systems from other manufacturers include DR DOS (1988), ROM-DOS (1989), PTS-DOS (1993), and FreeDOS (1998). MS-DOS dominated the IBM PC compatible market between 1981 and 1995.

The IBM Personal Computer Basic, commonly shortened to IBM BASIC, is a programming language first released by IBM with the IBM Personal Computer, Model 5150 in 1981. IBM released four different versions of the Microsoft BASIC interpreter, licensed from Microsoft for the PC and PCjr. They are known as Cassette BASIC, Disk BASIC, Advanced BASIC (BASICA), and Cartridge BASIC. Versions of Disk BASIC and Advanced BASIC were included with IBM PC DOS up to PC DOS 4. In addition to the features of an ANSI standard BASIC, the IBM versions offered support for the graphics and sound hardware of the IBM PC line. Source code could be typed in with a full-screen editor, and very limited facilities were provided for rudimentary program debugging. IBM also released a version of the Microsoft BASIC compiler for the PC, concurrently with the release of PC DOS 1.10 in 1982.

FlatBuffers is a free software library implementing a serialization format similar to Protocol Buffers, Thrift, Apache Avro, SBE, and Cap'n Proto, primarily written by Wouter van Oortmerssen and open-sourced by Google. It supports “zero-copy” deserialization, so that accessing the serialized data does not require first copying it into a separate part of memory. This makes accessing data in these formats much faster than data in formats requiring more extensive processing, such as JSON, CSV, and in many cases Protocol Buffers. Compared to other serialization formats however, the handling of FlatBuffers requires usually more code, and some operations are not possible.

References

  1. ↑ Discover the secrets of the Java Serialization API - article from Oracle
  2. ↑ For more detail go to: Jboss.org
  3. ↑ "ICCCM - Client to Window Manager Communication". Tronche.com. Retrieved 2014-03-20.
  4. ↑ William Stallings, Sistemas Operativos, 5th edition (2005), Page 311
  5. ↑ F. P. Brooks (1975). The Mythical Man-Month. p. 101. ISBN   0-201-00650-2.
  6. ↑ 1200 bytes, for IOCS functions such as OPEN and CLOSE
  7. ↑ 556 bytes, for device error handling
  8. ↑ "The MS-DOS Encyclopeida".
  9. ↑ Ray Duncan (January 12, 1988). "Examining the MS-DOS Environment". PC Magazine . pp. 349–352.
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