IBM Systems Application Architecture: Difference between revisions

Revision as of 22:48, 11 November 2013

Revision as of 03:17, 6 January 2014

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'''Systems Application Architecture''' ('''SAA''') is a set of standards for [[computer software]] developed by [[IBM]]. The SAA initiative was started in 1987 under the leadership of [[Earl Wheeler]], the "Father of SAA".<ref>{{cite news|last1=Bride|first1=Ed|last2=Desmond|first2=John|title=Wheeler: father of SAA - IBM VP and General manager of programming Systems Division Earl Wheeler; Systems Application Architecture - interview|url=http://findarticles.com/p/articles/mi_m0SMG/is_n15_v9/ai_8048960/|accessdate=June 20, 2012|newspaper=Software Magazine|date=Dec, 1989}}</ref> The intent was to implement SAA in IBM [[operating system]]s including [[MVS]], [[OS/400]] and [[OS/2]]. [[IBM AIX|AIX]], IBM's version of the [[UNIX]] operating system, was not a target of SAA, but does have interoperability with the SAA family.

SAA did not define new standards, but selected from among IBM's existing guidelines and software. IBM also purchased some third party software from developers such as [[Bachman Information Systems]], Index Technology, Inc., and [[KnowledgeWare|KnowledgeWare, Inc.]].<ref>{{cite news|title=IBM kauft sich für SAA Software-Know-how ein|url=http://www.computerwoche.de/heftarchiv/1989/35/1151816/|accessdate=June 21, 2012|newspaper=Computerwoche|date=1989-08-25}}</ref> These were intended to be implemented uniformly across all SAA compliant environments.

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The '''Common Programming Interface''' attempted to standardize compilers and [[application programming interface]]s among all systems participating in SAA, with the objective of providing "a common programming interface for the entire IBM computer product line - PCs, System/3x, System/370. This implies that under SAA, a program written for any IBM machine will run on any other".<ref name=Perna>{{cite web|last=Perna|first=Janet|title=SHARE 70: Session D010 - SAA Strategy Update: Application Software Support|url=http://www.redbug.org/dba/sharerpt/share70/d010.html|accessdate=June 18, 2012}}</ref>

CPI included a number of pieces<ref name=Linnell />{{rp|pp.46-5146–51}}:

* Programming languages &mdash; [[PL/I]], [[COBOL]], [[Fortran]], [[C (programming language)|C]], [[IBM RPG|RPG]] and [[REXX]].

* Application generator &mdash; [[IBM Cross System Product (CSP)]].

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'''Common User Access''' aimed at providing "a common user interface for the entire IBM product line. A user who sits down at a PC should see the same menus, keyboards and procedures that he would at a 3270 terminal."<ref name=Perna/>

Because of hardware differences complete commonality was impossible to attain. IBM created two CUA standards, the ''Basic Interface'' for [[IBM 3270]] and [[IBM 5250]] terminals, and the ''Advanced Interface'' for so-called "intelligent workstations", or PCs. The keyboard was standardized to the [[IBM PC keyboard#Keyboard_layoutsKeyboard layouts|"AT Enhanced" keyboard layout]] .<ref name=Linnell />{{rp|pp.39-4039–40}}

==Common communications services (CCS)==

'''Common Communications Services''' defined the methods by which hetrogeneous systems communicated. CCS depended on [[IBM Advanced Program-to-Program Communication|''Advanced Program-to-Program Communications'']], also known as APPC or [[IBM LU6.2|LU6.2]], [[IBM Systems Network Architecture|Systems Network Architecture]] (SNA) [[PU2.1]] or ''Low Entry Networking'' for [[peer to peer]] networking, and ''SNA Management Services'' for network control.<ref name=Linnell />{{rp|p.52}}

Three types of data links were supported:<ref name=Linnell />{{rp|pp.56-5856–58}}

* [[Synchronous Data Link Control]] (SDLC) high speed [[wide area network]]s.

* [[X.25]] packet-switched networks.

* [[Token ring]] [[local area network]]s (LAN).

CCS supported [[IBM 3270]] data streams, mainly for existing devices. [[Document Content Architecture]] specified a format for documents to be exchanged among different word processors and other software. [[IBM Intelligent Printer Data Stream (IPDS)|Intelligent Printer Data Stream (IPDS)]] was a page description language like Xerox [[Interpress]] or Adobe [[PostScript]]. Application services were provided by [[Snads|SNA Distribution Services (SNADS)]] for [[store and forward]] document transmission, Document Interchange Architecture (DIA) for electronic mail, and Distributed Data Management for file sharing.<ref name=Linnell />{{rp|pp.58-5958–59}}

==Common applications==