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 Unix (; trademarked as UNIX) is a family of multitasking, multiuser 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, an ...

systems manufacturers in 1984 to identify and promote open standards in the field of

information technology Information technology (IT) is the use of computers to create, process, store, retrieve, and exchange all kinds of Data (computing), data . and information. IT forms part of information and communications technology (ICT). An information te ...

. 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, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also i ...

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 castrated) adult male of the species ''Bos taurus'' (cattle). More muscular and aggressive than the females of the same species (i.e., cows), bulls have long been an important symbol in many religions, includin ...

, ICL, Siemens,

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 par ...

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

Philips Koninklijke Philips N.V. (), commonly shortened to Philips, is a Dutch multinational conglomerate corporation that was founded in Eindhoven in 1891. Since 1997, it has been mostly headquartered in Amsterdam, though the Benelux headquarters i ...

and

Ericsson (lit. "Telephone Stock Company of LM Ericsson"), commonly known as Ericsson, is a Swedish multinational networking and telecommunications company headquartered in Stockholm. The company sells infrastructure, software, and services in informa ...

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 in ...

, 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. is an American multinational telecommunications holding company headquartered at Whitacre Tower in Downtown Dallas, Texas. It is the world's largest telecommunications company by revenue and the third largest provider of mobile te ...

, Digital, Hewlett-Packard, Sun Microsystems,

Unisys Unisys Corporation is an American multinational information technology (IT) services and consulting company headquartered in Blue Bell, Pennsylvania. It provides digital workplace solutions, cloud, applications, and infrastructure solutions, ...

, 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 (natively Nokia Oyj, referred to as Nokia) is a Finnish multinational telecommunications, information technology, and consumer electronics corporation, established in 1865. Nokia's main headquarters are in Espoo, Finland, i ...

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

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

Apollo Computer Apollo Computer Inc., founded in 1980 in Chelmsford, Massachusetts, by William Poduska (a founder of Prime Computer) and others, developed and produced Apollo/Domain workstations in the 1980s. Along with Symbolics and Sun Microsystems, Apollo ...

from North America; Fujitsu, Hitachi, and

NEC is a Japanese multinational information technology and electronics corporation, headquartered in Minato, Tokyo. The company was known as the Nippon Electric Company, Limited, before rebranding in 1983 as NEC. It provides IT and network soluti ...

from Japan; plus the

Open Software Foundation The Open Software Foundation (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. Despit ...

and Unix International. 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, 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 over 840 member organizations and provides a number of servi ...

. 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 both the system- and user-level application programming inter ...

, 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, 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 Single UNIX Specification 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