Preface

This issue contains papers on seven subjects: theevolution and design of user interfaces such asthe Common User Access* (CVA*) WorkplaceModel, the Distributed Data Management (DDM)architecture and its implementation in the Cus-tomer Information Control System (CICS), a dis-cussion of the data description and conversionarchitecture and data language that has beenadopted for Systems Application Architecture*(SAA*) programs, a heterogeneous multiprocess-ing environment resulting from the creation of aSystem/370* and Personal System/2* BiProces-sor, Project Athena** and its impact on distrib-uted computing, considerations for the design ofdistributed applications, and the extension andformalization of Zachman's information systemsarchitecture.

The first subject is the evolution and design ofuser interfaces, such as the Workplace Model forCommon User Access (CVA), which is covered intwo papers. Berry and Reeves describe the influ-ences, technological shifts, and factors that canbe observed in the evolution of the CVA Work-place Model, showing how interface designs andstyles are affected over the long term. They relatetheir discussion to the implementation of theWorkplace Model in the OS/2* Version 2.0 Work-place Shell ". The paper also describes many ofthe features of the model and their evolutionaryorigins.

The second paper on user interfaces, by Berry,provides an introduction to three types of inter-face models-the user's conceptual model, theinterface designer's model, and the programmer'smodel-and the ways in which those models in-fluenced the rationale and design of the CVAWorkplace Model. An extensive description isgiven of the designer's model for the Workplace

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Model, showing its object orientation and pre-senting its features and capabilities from the de-signer's viewpoint.

The next two subjects are Distributed Data Man-agement (DDM) architecture and the data descrip-tion and conversion (DD&C) architecture with itsdata language, which are treated in a series ofthree papers. The first paper in the series ad-dresses the evolution and framework of the DDMarchitecture as a suite of five layers for distributedapplication services within the object-orientedparadigm: the distributed system layer, the cli-ent/server layer, the manager layer, the objectlayer, and the data layer. Demers, Fisher, Gai-tonde, and Sanders show the architecture of eachlayer and the services that each provides for theuser and for each other.

The second paper in this series, by Demers andYamaguchi, provides the rationale, a descriptionof the architecture, and a discussion of the datalanguage for enhanced data interchange as adoptedfor Systems Application Architecture (SAA) envi-ronments. The resulting DD&C architecture is sup-ported by A Data Language (ADL) that treats bothdata description and data conversion, an efficientmethod for encoding ADL, and programs thattranslate between ADL and other programminglanguages.

The final paper in this series shows how hetero-geneous and distributed files are supported in on-line transaction processing systems such as theCustomer Information Control System (CICS)through the provision of data management capa-bilities by CICS/DDM. Deinhart discusses themerger of CICS and the DDM architecture, and theresulting benefits for transaction processing andfor SAA.

IBM SYSTEMS JOURNAL, VOL 31, NO 3, 1992

The rernammg four papers treat separate sub-jects. Berggren presents the results of the cre-ation of a heterogeneous multiprocessing envi-ronment by the connecting and merging of aSystem/370 and a Personal Systeml2 into a Bi-Processor. The closely coupled connection is ef-fected by a high-speed pipe, which allows eachprocessor to take advantage of the other's capa-bilities without inhibiting the capabilities of eitherone. This is termed concurrent coprocessing. Ob-jectives of this project and possible applicationsare described.

Project Athena started in 1983 as an initiative ofthe Massachusetts Institute of Technology (MIT),with the support and cooperation of the DigitalEquipment Corporation (DEC) and IBM. The goalwas to provide distributed computing services onMIT's campus and to learn what would be requiredof such broad distributed systems in the future.Arfman and Roden discuss the origins of the proj-ect, the realization of the goals over the next dec-ade, and the evolution to the mature, heteroge-neous, distributed computing environment thatexists today. Many other technical projects, stan-dards, and products had their start as part ofProj-ect Athena.

As more and more systems and programs eitheroperate in a distributed processing arena or be-come inherently distributed in their structure,programmers will need to understand the consid-erations that affect the design of distributed ap-plications. Rofrano presents the results of an ex-tensive exploration of these design considerations,including the questions of data placement, functionplacement, and design methods. He treats the fun-damental tradeoffs that must be addressed for thedesign of any distributed application, and especiallyfor those operating in a heterogeneous machineenvironment.

Sowa and Zachman provide an update, exten-sion, and formalization of the information sys-tems architecture (ISA) first presented in thesepages in 1987 by Zachman and widely adoptedand accepted thereafter. The extensions addressthe who, when, and why dimensions that werenot part of the original model showing the what,how, and where dimensions of information sys-tems design. The formalism is represented byconceptual graphs.

IBM SYSTEMS JOURNAL, VOL 31, NO 3, 1992

The next issue of the Journal will be devoted toEuropean cooperative efforts involving IBM, inthis noteworthy year for Europe's future-1992.

Gene F. HoffnagleEditor

*Trademark or registered trademark of International BusinessMachines Corporation,**Trademark or registered trademark of the MassachusettsInstitute of Technology.

It has come to our attention that one of the papersin our special issue on APL (Volume 30, Number4, 1991)-"Extending the domain of APL" byM. T. Wheatley-was published in "APL-icationConference Proceedings" (1988), edited by P.Goacher under the auspices of the British APLAssociation. As a refereed, archival journal it isnot our practice nor intent to publish material thathas appeared before in a public medium, whethercopyrighted or not. Quoted passages and special-ized figures may be reprinted with approval of theeditor and submission of any required permis-sions. Authors bear the responsibility for submit-ting only original, unpublished work and for in-forming the editor whenever that work has beensubmitted elsewhere for simultaneous or priorconsideration.-Ed.

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