X/Open group (also known as the Open Group for Unix Systems and incorporated in 1987 as X/Open Company, Ltd.) was a

consortium A consortium () is an association of two or more individuals, companies, organizations, or governments (or any combination of these entities) with the objective of participating in a common activity or pooling their resources for achieving a ...

founded by several European

UNIX Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...

systems manufacturers in 1984 to identify and promote

open standard An open standard is a standard that is openly accessible and usable by anyone. It is also a common prerequisite that open standards use an open license that provides for extensibility. Typically, anybody can participate in their development due to ...

s in the field of

information technology Information technology (IT) is a set of related fields within information and communications technology (ICT), that encompass computer systems, software, programming languages, data processing, data and information processing, and storage. Inf ...

. More specifically, the original aim was to define a single specification for

operating system An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ...

s derived from UNIX, to increase the interoperability of applications and reduce the cost of porting software. Its original members were

Bull A bull is an intact (i.e., not Castration, castrated) adult male of the species ''Bos taurus'' (cattle). More muscular and aggressive than the females of the same species (i.e. cows proper), bulls have long been an important symbol cattle in r ...

, ICL,

Siemens Siemens AG ( ) is a German multinational technology conglomerate. It is focused on industrial automation, building automation, rail transport and health technology. Siemens is the largest engineering company in Europe, and holds the positi ...

Olivetti Olivetti S.p.A. is an Italian manufacturer of computers, tablets, smartphones, printers and other such business products as calculators and fax machines. Headquartered in Ivrea, in the Metropolitan City of Turin, the company has been owned b ...

, and Nixdorf—a group sometimes referred to as BISON.

Philips Koninklijke Philips N.V. (), simply branded Philips, is a Dutch multinational health technology company that was founded in Eindhoven in 1891. Since 1997, its world headquarters have been situated in Amsterdam, though the Benelux headquarter ...

and

Ericsson (), commonly known as Ericsson (), is a Swedish multinational networking and telecommunications company headquartered in Stockholm, Sweden. Ericsson has been a major contributor to the development of the telecommunications industry and is one ...

joined in 1985, at which point the name X/Open was adopted. The group published its specifications as

X/Open Portability Guide X/Open group (also known as the Open Group for Unix Systems and incorporated in 1987 as X/Open Company, Ltd.) was a consortium founded by several European UNIX systems manufacturers in 1984 to identify and promote open standards in the field of info ...

, starting with Issue 1 in 1985, and later as ''X/Open CAE Specification''. In 1987, X/Open was incorporated as X/Open Company, Ltd. By March 1988, X/Open grew to 13 members:

AT&T AT&T Inc., an abbreviation for its predecessor's former name, the American Telephone and Telegraph Company, is an American multinational telecommunications holding company headquartered at Whitacre Tower in Downtown Dallas, Texas. It is the w ...

Digital Digital usually refers to something using discrete digits, often binary digits. Businesses *Digital bank, a form of financial institution *Digital Equipment Corporation (DEC) or Digital, a computer company *Digital Research (DR or DRI), a software ...

Hewlett-Packard The Hewlett-Packard Company, commonly shortened to Hewlett-Packard ( ) or HP, was an American multinational information technology company. It was founded by Bill Hewlett and David Packard in 1939 in a one-car garage in Palo Alto, California ...

Sun Microsystems Sun Microsystems, Inc., often known as Sun for short, was an American technology company that existed from 1982 to 2010 which developed and sold computers, computer components, software, and information technology services. Sun contributed sig ...

Unisys Unisys Corporation is a global technology solutions company founded in 1986 and headquartered in Blue Bell, Pennsylvania. The company provides cloud, AI, digital workplace, logistics, and enterprise computing services. History Founding Unis ...

, NCR, Olivetti, Bull, Ericsson, Nixdorf, Philips, ICL, and Siemens. By 1990 the group had expanded to 21 members: in addition to the original five,

and

Nokia Nokia Corporation is a Finnish multinational corporation, multinational telecommunications industry, telecommunications, technology company, information technology, and consumer electronics corporation, originally established as a pulp mill in 1 ...

from Europe; AT&T, Digital, Unisys, Hewlett-Packard,

IBM International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...

, NCR, Sun,

Prime Computer Prime Computer, Inc. was a Natick, Massachusetts-based producer of minicomputers from 1972 until 1992. With the advent of Personal computer, PCs and the decline of the minicomputer industry, Prime was forced out of the market in the early 1990s, ...

Apollo Computer Apollo Computer Inc. was an American technology corporation headquartered and founded in Chelmsford, Massachusetts. It was founded in 1980 by William Poduska (a founder of Prime Computer) and others. Apollo Computer developed and produced Apoll ...

from North America; Fujitsu,

Hitachi () is a Japanese Multinational corporation, multinational Conglomerate (company), conglomerate founded in 1910 and headquartered in Chiyoda, Tokyo. The company is active in various industries, including digital systems, power and renewable ener ...

, and

NEC is a Japanese multinational information technology and electronics corporation, headquartered at the NEC Supertower in Minato, Tokyo, Japan. It provides IT and network solutions, including cloud computing, artificial intelligence (AI), Inte ...

from Japan; plus the

Open Software Foundation The Open Software Foundation, Inc. (OSF), was a not-for-profit industry consortium for creating an open standard for an implementation of the operating system Unix. It was formed in 1988 and merged with X/Open in 1996, to become The Open Group. ...

and

Unix International Unix International (UI) was an association created in 1988 to promote open standards, especially the Unix operating system. Its most notable members were AT&T and Sun Microsystems, and in fact the commonly accepted reason for its existence was as ...

. In October 1993, a planned transfer of UNIX trademark from Novell to X/Open was announced; it was finalized in 2nd quarter of 1994. In 1994, X/Open published the

Single UNIX Specification The Single UNIX Specification (SUS) is a standard for computer operating systems, compliance with which is required to qualify for using the "UNIX" trademark. The standard specifies programming interfaces for the C language, a command-line shell, ...

, which was drawn from XPG4 Base and other sources. In 1996, X/Open merged with the

to form

The Open Group The Open Group is a global consortium that seeks to "enable the achievement of business objectives" by developing " open, vendor-neutral technology standards and certifications." It has 900+ member organizations and provides a number of services ...

. X/Open was also responsible for the XA protocol for heterogeneous distributed transaction processing, which was released in 1991.

X/Open Portability Guide

X/Open published its specifications under the name X/Open Portability Guide (or XPG). Based on the AT&T

System V Interface Definition The System V Interface Definition (SVID) is a standard that describes the AT&T UNIX System V behavior, including that of system calls, C libraries, available programs and devices. While it was not the first attempt at a standardizations document ...

, the guide has a wider scope than

POSIX The Portable Operating System Interface (POSIX; ) is a family of standards specified by the IEEE Computer Society for maintaining compatibility between operating systems. POSIX defines application programming interfaces (APIs), along with comm ...

, which is only concerned with direct operating system interfaces. The guide specifies a ''Common Application Environment'' (CAE) intended to allow portability of applications across operating systems. The primary aim was compatibility between different vendors' implementations of

, though some vendors also implemented the standards on non-UNIX platforms. Issue 1 of the guide covered basic operating system interfaces, the C language, COBOL, indexed sequential file access method (ISAM) and other parts and was published in 1985. Issue 2 followed in 1987, and extended the coverage to include Internationalization, Terminal Interfaces, Inter-Process Communication, and the programming languages C,

COBOL COBOL (; an acronym for "common business-oriented language") is a compiled English-like computer programming language designed for business use. It is an imperative, procedural, and, since 2002, object-oriented language. COBOL is primarily ...

, FORTRAN, and Pascal, as well as data access interfaces for SQL and ISAM. In many cases these were profiles of existing international standards. Issue 3 (XPG3) followed in 1989, its primary focus being convergence with the

operating system specifications; it added Window Manager, ADA Language and more. Issue 4 (XPG4) was published in July 1992. The

was based on the XPG4 standard. The XPG3 and XPG4 standards define all aspects of the operating system, programming languages and protocols which compliant systems should have. Multiple levels of compliance and corresponding labels were available, depending on the scope of the guide that was covered: Base and Plus; labels Component and Application are for SW components and applications that make use of the portability guide. Issue 1 was published as a single publication with multiple parts, . Issue 2 was published in multiple volumes: * X/Open Portability Guide Volume 1: System V Specification Commands and Utilities, 1987, * X/Open Portability Guide Volume 2: System V Specification System Calls and Libraries, 1987, * X/Open Portability Guide Volume 3: System V Specification Supplementary Definitions, 1987, * X/Open Portability Guide Volume 4: Programming Languages, 1987, * X/Open Portability Guide Volume 5: Data Management, 1987, Issue 3 was published in multiple volumes: * X/Open Portability Guide Volume 1: XSI Commands and Utilities, 1989, * X/Open Portability Guide Volume 2: XSI System Interface and Headers, 1989, * X/Open Portability Guide Volume 3: XSI Supplementary Definitions, 1989, * X/Open Portability Guide Volume 4: Programming Languages, 1988, * X/Open Portability Guide Volume 5: Data Management, 1988, * X/Open Portability Guide Volume 6: Window Management, 1988, * X/Open Portability Guide Volume 7: Networking Services, 1988, The XPG4 Base specification includes the following documents: * System Interfaces and Headers (XSH), Issue 4, 1992, , C202 * Commands and Utilities (XCU), Issue 4, 1992, , C203 * System Interface Definitions (XBD), Issue 4, 1992, , C204 The above three documents were published not under the label ''X/Open Portability Guide'' but rather as ''CAE Specification''. Nonetheless, the term ''X/Open Portability Guide, Issue 4'' sees some use in reference to 1992 year of publication. Further X/Open publications under the label ''X/Open CAE Specification'' rather than ''X/Open Portability Guide'': * Distributed Transaction Processing: The XA Specification, December 1991, * Systems Management: Management Protocol Profiles (XMPP), October 1993, * X/Open DCE: Remote Procedure Call, August 1994, * System Interface Definitions, Issue 4, Version 2, September 1994, * System Interfaces and Headers, Issue 4, Version 2, September 1994, * Commands and Utilities, Issue 4, Version 2, September 1994, * Networking Services, Issue 4, September 1994, * Data Management:SQL Call Level Interface (CLI), March 1995, * File System Safe UCS Transformation Format (UTF-8), March 1995, * Distributed Transaction Processing: The TX (Transaction Demarcation) Specification, April 1995, * X.25 Programming Interface using XTI (XX25), November 1995, * Distributed Transaction Processing: The TxRPC Specification, November 1995, * Distributed Transaction Processing: The XATMI Specification, November 1995, * Distributed Transaction Processing: The XCPI-C Specification Version 2, November 1995, * X/Open Curses, Issue 4, 1995, * X/Open Curses, Issue 4, Version 2, 1996, * Data Management: Structured Query Language (SQL) Version 2, March 1996, * And more.

References

* - Mentions X/Open; lists members and its efforts to define "a new standard interface to UNIX". * C. B. Taylor. The X/OPEN group and the common application environment. ICL Technical Journal Vol 5(4) pp. 665–679, 1987. * C. B. Taylor. X/Open - from Strength to Strength. ICL Technical Journal, Vol 7(3) pp. 565–583, 1991 * C. B. Taylor. X/Open and Open Systems. X/Open Company Limited, 1992.

External links

The Open Group
opengroup.org—resulted from merger of X/Open Company and Open Software Foundation

unix.org
X/Open Portability Guide
issue 1, 1985 {{DEFAULTSORT:X Open History of software Software engineering papers Standards organisations in the United Kingdom Technology consortia Unix history Unix standards

X/Open Portability Guide

See also

References

External links