Proceedings of the ECSCW'95 Workshop on the Role of Version Control in CSCW Applications

The workshop entitled "The Role of Version Control in Computer Supported Cooperative Work Applications" was held on September 10, 1995 in Stockholm, Sweden in conjunction with the ECSCW'95 conference. Version control, the ability to manage relationships between successive instances of artifacts, organize those instances into meaningful structures, and support navigation and other operations on those structures, is an important problem in CSCW applications. It has long been recognized as a critical issue for inherently cooperative tasks such as software engineering, technical documentation, and authoring. The primary challenge for versioning in these areas is to support opportunistic, open-ended design processes requiring the preservation of historical perspectives in the design process, the reuse of previous designs, and the exploitation of alternative designs. The primary goal of this workshop was to bring together a diverse group of individuals interested in examining the role of versioning in Computer Supported Cooperative Work. Participation was encouraged from members of the research community currently investigating the versioning process in CSCW as well as application designers and developers who are familiar with the real-world requirements for versioning in CSCW. Both groups were represented at the workshop resulting in an exchange of ideas and information that helped to familiarize developers with the most recent research results in the area, and to provide researchers with an updated view of the needs and challenges faced by application developers. In preparing for this workshop, the organizers were able to build upon the results of their previous one entitled "The Workshop on Versioning in Hypertext" held in conjunction with the ECHT'94 conference. The following section of this report contains a summary in which the workshop organizers report the major results of the workshop. The summary is followed by a section that contains the position papers that were accepted to the workshop. The position papers provide more detailed information describing recent research efforts of the workshop participants as well as current challenges that are being encountered in the development of CSCW applications. A list of workshop participants is provided at the end of the report. The organizers would like to thank all of the participants for their contributions which were, of course, vital to the success of the workshop. We would also like to thank the ECSCW'95 conference organizers for providing a forum in which this workshop was possible

Development of a process simulator using object oriented programming: Information modeling and program structure

Object Oriented Programming Languages (OOPL) offer the flexibility of language extension to the specific application of interest. The development effort required for process simulators can be greatly reduced if we extend OOPL with process simulator specific objects and use them for simulation. Design of objects is the most important aspect of development in using OOPL. But OOPL do not provide a methodology to aid in object design. The objects to be designed should reflect the nature of the application at hand.;The objective of this work is to develop an object oriented process simulator to illustrate the benefit of using OOPL in process simulation. An object design criteria is established, an analysis of the object model is performed, and a steady state process simulator using sequential and simultaneous approaches is developed using C++ as the underlying implementation language.;It is found that the object model has to be extended with operational behavior to effectively represent the process simulation information, the development effort is greatly reduced by using the object oriented approach for the process simulator, OOPL can act as common platforms for integrating process engineering activities, and C++ can be effectively used as an implementation language for object oriented process simulation.;Further work is necessary to extend the simulator with dynamic simulation capabilities and to make the simulator interactive and user friendly by developing a graphic interface

CAD-tietokannat

Tämä pro gradu -tutkielma on kirjallisuuskatsaus CAD-tietokannoista. CAD (Computer-Aided Design) tarkoittaa tietokoneavusteista suunnittelua. CAD-ohjelmilla mallinnettavat objektit ovat tyypillisesti monimutkaisia rakenteeltaan. Niissä on toisiinsa yhteydessä olevia entiteettejä, ja niiden rakenne on usein hierarkkista. Objektit voivat olla koottuja objekteja, jotka sisältävät toisia objekteja. Tämä aikaansaa tietokannalle erityisiä vaatimuksia. CAD-tietokannan tulee pystyä käsittelemään suuria datamääriä, ja datan monimutkaiset keskinäiset suhteet ovat esitettävä riittävästi. Tietokannan täytyy pystyä käsittelemään datan dynaamista luonnetta. Tämä johtuu siitä, että käyttäjä voi suunnitteluprosessin edetessä määritellä uusia dataluokkia ja muuttaa niitä. Tietokannan tulee myös muun muassa olla riittävän joustava, tukea eri versioita ja huolehtia datan eheydestä. Rajoitusten käsittelykin on yleensä poikkeuksellista CAD-tietokannoissa, johtuen muun muassa poikkeuksellisen pitkistä tapahtumasarjoista. Yleisimmät CAD-järjestelmissä käytettävät tietokantamallit ovat hierarkkinen, verkkomallin, relaatio-, oliomallin ja olio-relaatiomallin tietokanta. Näissä kaikissa malleissa on hyvät ja huonot puolensa. Hierarkkista ja verkkomallin tietokantoja käytetään edelleen, vaikka ne ovat vanhoja. Relaatiotietokantaa pidetään hierarkkista ja verkkomallin tietokantoja parempana muun muassa sen loogisuuden ja yksinkertaisuuden takia. Oliomallin tietokantaa pidetään monissa lähteissä parhaana CAD-järjestelmiin. Se ei kuitenkaan ole syrjäyttänyt muita tietokantamalleja

A Framework for Data Sharing in Computer Supported Cooperative Environments

Concurrency control is an indispensable part of any information sharing system. Co-operative work introduces new requirements for concurrency control which cannot be met using existing applications and database management systems developed for non-cooperative environments. The emphasis of concurrency control in conventional database management systems is to keep users and their applications from inadvertently corrupting data rather than support a workgroup develop a product together. This insular approach is necessary because applications that access the database have been built with the assumptions that they have exclusive access to the data they manipulate and that users of these applications are generally oblivious of one another. These assumptions, however, are counter to the premise of cooperative work in which human-human interaction is emphasized among a group of users utilizing multiple applications to jointly accomplish a common goal. Consequently, applying conventional approaches to concurrency control are not only inappropriate for cooperative data sharing but can actually hinder group work. Computer support for cooperative work must therefore adopt a fresh approach to concurrency control which does promote group work as much as possible, but without sacrifice of all ability to guarantee system consistency. This research presents a new framework to support data sharing in computer supported cooperative environments; in particular, product development environments where computer support for cooperation among distributed and diverse product developers is essential to boost productivity. The framework is based on an extensible object-oriented data model, where data are represented as a collection of interrelated objects with ancillary attributes used to facilitate cooperation. The framework offers a flexible model of concurrency control, and provides support for various levels of cooperation among product developers and their applications. In addition, the framework enhances group activity by providing the functionality to implement user mediated consistency and to track the progress of group work. In this dissertation, we present the architecture of the framework; we describe the components of the architecture, their operation, and how they interact together to support cooperative data sharing