Patterson, J. F, Comparing the Programming Demands of Single-user and Multi-user Applications,In Proc.of 4 annual ACM symposium on User interface software and technology, Hilton Head, SC, Nov.1991, pp.11-13.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....expected. We now describe the main reasons for this: inappropriate software tools, complexity of data transfer and routing, variety of naming schemes and data formats. Widely available operating systems and computer networks already provide little support for implementing distributed systems [Patt91] For example, the Unix operating system and the Ethernet network cannot guarantee bounded time execution. Also, most existing tools for developing distributed systems are either not widely available, too low level, or not suitable for developing groupware. Most systems were developed for ....

Patterson, J., F., Comparing the programming demands of single-user and multi-user applications.In Proceedings of the fourth Symposium on User Interface Software and Technology, pages 87--94. ACM SIGCHI, ACM Press, November 1991.

....interfaces. For example, the provision of public and private views, where certain parts of a users interface can be seen only by that user (private or personal) whereas others may be visible by all users (public) Provision of such views permits a control over sharing of information. Patterson [13] states The essence of multi user applications is sharing and control over sharing . Further control over sharing is shown in Grove [4] where a shared view is implemented, as well as a public and private. This view allows a subset of users to access the information held within it. We wish to ....

Patterson, JF. "Comparing the Programming Demands of Single-User and Multi-User Applications". Proc. Symposium on User Interface Software and Technology, Hilton Head, South Carolina, November 1991. Pages: 87-94.

.... While in single user applications the non preemptive scheduling (wherean action that follows an input proceeds until the control is released) is suitable for managing inputs, this may not be acceptable for multiuser inputs because lengthy computations cause delays on the responses to other users [Patterson 91] RENDEZVOUS [Patterson 90] uses light weight processes to implement preemptive scheduling and consequently allow interleaving of actions and prompt feedback to all users. MMM [Bier 91] uses a different approach. Input notifications are broadcasted to a distributed application with timeouts for ....

J. Patterson. Comparing the programming demands of single-user and multi-user applications. In Proceedings of the ACM Symposium on User Interface Software and Technology. ACM Press, 1991.

....information services such as travel planning (e.g. giving directions, pointing out sites of interest, etc. Brinck and Gomez, 1992] ffl Collaborative writing and editing, e.g. Bier and Freeman, 1991, Haake and Wilson, 1992, Olson et al. 1990] ffl Multi player games, such as card games [Patterson, 1991]. Many games involve more environmental information than just the explicit state of the game alone represents. Thus, the degree to which other environmental factors are represented might determine the perceived quality of the game, and influence the performance of the players. Applications with ....

....self. Similarly, players of card games will have different views of the card table and private views of their own cards. An example of a system which focuses on support for different views of group activity is Bellcore s Rendezvous system ( Brinck and Gomez, 1992, Hill, 1992, Hill et al. 1993, Patterson, 1991, Patterson et al. 1990] CardTable [Hill et al. 1993, Patterson, 1991] is a Rendezvous application which provides individual perspectives of a shared group activity, specifically, of players in card games. Non human elements of a groupware system might also be considered as participants, to ....

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Patterson, J. F. (1991). Comparing the Programming Demands of Single--User and Multi--User Applications. In [Mackinlay, 1991], pages 87--94.

....revisiting the issues and by explaining further architectural differences possible in collaborative applications. GROUPWARE TOOLKITS FOR SYNCHRONOUS WORK 3 1.2.1 Centralized vs. Replicated Architectures Groupware researchers have long argued the merits of centralized vs. replicated architectures [1, 22, 45, 46, 56, 28, 79, 37, 55, 12, 20]. Centralized architectures use a single application program, residing on one central server machine, to control all input and output to the distributed participants. Client processes residing at each site are responsible only for passing requests to the central program, and for displaying any ....

....display[1] XOpenDisplay ( Display1 ) display[2] XOpenDisplay ( Display2 ) for (i=1; i =2; i ) XDrawPoint (display[i] 20, 100) XCloseDisplay(display[i] GROUPWARE TOOLKITS FOR SYNCHRONOUS WORK 7 1.2.3. 2 Rendezvous: a centralized architecture The Rendezvous groupware toolkit [37, 57, 56, 36] is heavily modeled on the idea of maintaining a single abstract data model that is shared by everyone. As mentioned earlier, multiple views of that model can be drawn differently on each person s display. Rendezvous places both the single abstraction and the view models on a single processor. Its ....

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Patterson, J.F. (1991) "Comparing the programming demands of single-user and multi-user applications. " in Proceedings of the UIST'92 Symposium on User Interface Software and Technology, p87--94, Hilton Head, South Carolina, November 11--13.

....data and an extensible shared graphics model. As many groupware applications can be seen as shared visual work surfaces, a toolkit should support the creation and manipulation of both generic and application specific objects on a graphical work surface. Paradigms such as Abstraction Link View (Patterson, 1991) can be supported by the toolkit to facilitate this. shared graphics primitives . object concurrency control . separate view from object representation Table 1. Core requirements for a groupware toolkit Building real time groupware with GroupKit 4 Roseman and Greenberg, July 1995 The ....

....all sites. GroupKit s environments are an effective way to support the programming model advocated in part by Smalltalk s model view controller (Krasner and Pope 1988) and later by Patterson. Both argue for separating the view of an object from its data representation. In the Rendezvous toolkit, Patterson (1991) encourages developers to create groupware applications using its abstraction link view (ALV) model, whose constructs are: a shared underlying data abstraction, a view of the abstracted entity that may differ for each user, a constraint (called a link) that automatically adjusts the view ....

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Patterson, J.F. (1991) "Comparing the Programming Demands of Single-User and Multi-User Applications." in Proceedings of the UIST`92 Symposium on User Interface Software and Technology, November 11-13, Hilton Head, South Carolina, p87-94, ACM Press.

....windows, whiteboards, structured drawing systems, and shared editors. But work surfaces can be far more powerful and specialized than that. For example, WYSIWIS could be relaxed so that people could view the work surface from different perspectives; an example would be a competitive card game [26]. Specialized applications could expand the notion of work surface to include tools for voting, brainstorming, organizing ideas, and so on. This paper discusses our toolkit design philosophy, as embodied in GROUPKIT. We begin by listing a preliminary set of requirements for groupware toolkits, ....

....type of shared object, be it structured graphics or a text buffer. Concurrency control is often needed to mediate access to the object, for example, two people trying to manipulate the same point on a line. In fact several concurrency schemes have already been implemented in groupware toolkits [25,26,11]. Concurrency can be achieved through simple locking, transaction mechanisms, or numerous other schemes [8] In addition, the degree of concurrency and access to shared objects can be specified through the notion of flexible coupling [6] m) Separate the view of an object from its underlying ....

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Patterson, J.F. Comparing the programming demands of single-user and multi-user applications. In Proc. User Interface Software and Technology (UIST '91), Nov. 11--13 1991, pp. 87-91.

....the state ofthe art in supporting collaboration in widely dispersed working groups. A number of researchers have suggested that for this situation to change requires tools that assist with the complex task of building cooperative systems, and a common platform to facilitate system deployment [14, 5]. The Web is the first example of a truly global, platform independent, distributed systems technology enabling development of CSCW systems. The Basic Support for Cooperative Work project (BSCW) at GMD is attempting to take advantage of the Web as an enabling technology for CSCW. We are extending ....

Patterson, J., Comparing the programming demands of single-user and multi-user applications, in Proceedings of UIST'91, ACM Press, Hilton Head, November, 1991, pp 87-94.

.... While in single user applications the non preemptive scheduling (where an action that follows an input proceeds until the control is released) is suitable for managing inputs, this may not be acceptable for multiuser inputs because lengthy computations cause delays on the responses to other users [40]. RENDEZVOUS [41] uses light weight processes to implement preemptive scheduling and consequently allow interleaving of actions and prompt feedback to all users. MMM [9] uses a different approach. Input notifications are broadcasted to a distributed application with timeouts for responses. If the ....

J. Patterson. Comparing the programming demands of single-user and multi-user applications. In Proceedings of the ACM Symposium on User Interface Software and Technology. ACM Press, 1991.

....the two users to create private comments in their comments windows and see different presentations of the cutoff scores. Logical separation makes it easy to create multiple user interfaces such as these that access a common functional core. For this reason, multi user Suite [8] Rendezvous [22, 23], GROVE [9] and CES [13] support this principle. Logical separation is also necessary to support the principles of concurrent command processing and physical separation, which are described below. Figure 1: An Example Multi User Application Multiple, Dynamic Linkage It should be possible to ....

....that handle collaboration in the UIMS layer. 3. CONCLUSIONS AND FUTURE WORK The current multi user systems have adopted a wide range of approaches. For instance, some systems such as VConf [17] Rapport [10] and [1] handle collaboration in the window layer, while others such as Rendezvous [22, 23] and multi user Suite [7, 8] handle it in the UIMS layer; some systems such as VConf and Rapport support only collaboration transparent programs, while others such as Colab [27] and Rendezvous support only collaboration aware programs; and some systems such as Rendezvous and multiuser Suite ....

John F. Patterson, Comparing the Programming Demands of Single-User and MultiUser Applications, Proceedings of the 4th ACM SIGRAPH Conference on User Interface Software and Technology, pp. 79-86 (November 1991).

.... The design decisions embedded within applications can be identified and made accessible to allow ease of modification Logical separation is desirable for single user interfaces but the multi user case requires such separation to support the alternative visualisations needed for view level sharing [4]. In addition, physical separation provides a degree of fault tolerance; a user interface process may crash without crashing other user interface or application processes. Physical separation also allows execution of interface and application processes on different machines providing local ....

Patterson, J. F., Comparing the programming demands of single-user and multi-user applications, Proceedings of the Conference on User Interface Software Technology (UIST'91), November 11-13, 1991, Hilton Head, South Carolina, ACM Press, pp 8794

....and presents directions for future work. 2 ACCESS REQUIREMENTS We have identified several requirements that a generic access control model for collaborative environments should support: Multiple, dynamic user roles: The model should allow users access rights to be inferred from their roles [9]. Moreover, it should allow users to take multiple roles simultaneously and change these roles dynamically during different phases of collaboration. Collaboration rights: Besides traditional operations such as read and write, all other operations whose results can affect multiple users should be ....

John F. Patterson. Comparing the programming demands of single-user and multi-user applications. In Proc. of the 4th ACM SIGRAPH Conf. on User Interface Software and Technology, pages 79--86, November 1991.

....Dewan and R. Choudhary Coupling User Interfaces d30 coupling model and communication systems are complementary and address the problem of communicating information among different users at different levels. 6.4. The Rendezvous Coupling Model Flexible coupling is also supported by the Rendezvous [26,27] architecture for implementing multiuser programs, which was developed independently about the same time as this work. Rendezvous defines a flexible coupling model that supports semantics, syntax, presentation, and access couplings. It also supports an implementation model that supports abstract ....

John F. Patterson, "Comparing the Programming Demands of Single-User and Multi-User Applications," Proceedings of the 4th ACM SIGRAPH Conference on User Interface Software and Technology, November 1991, pp. 79-86.

....object. Provision of such views permits a control over sharing of information. In this respect we agree with Patterson [11] when he states The essence of multi user applications is sharing and control over sharing . However, in contrast to the constraint based approach exploited within Rendezvous[21] we have chosen to extend existing multi user control techniques to incorporate user interfaces. The following sections consider the provision of facilities to manage the cooperative aspects of the user interface provided by our shared interface objects. We begin by considering the use of an ....

Patterson J., "Comparing the programming demands of single user and multi-user applications". Proc. of ACM Symposium on User Interface Software and Technology (UIST) November 1991. pp 87-94

....should be free to concentrate on the semantics of the application and what should be provided. The programmer should not need to worry about how the mechanisms employed obtain the required result. The development of this support is essential to the future of CSCW and we would agree with (Patterson, 1991) when he argues: If multi user applications are to flourish in the future, then programmers will require support for building these applications . This paper presents a platform to support group working by providing mechanisms for sharing Cooperating Objects in Lightweight Activities (COLA) ....

Patterson, J.F. (1991): "Comparing the Programming demands of Single-User and Multi-User applications."User Interface Software and Technology (UIST), November 11-13, 1991, pp.8795.

....more objective because we do not use a single trial application program as the basis of our evaluation. Of the tools we have selected, GroupKit and multi user Suite are included in Dewan s survey. In his paper comparing the programming demands of single user and multi user applications, Patterson [54] proposes a list of three dimensions of programming complexity that are of special concern to multi user application programmers. The three dimensions are: concurrency, abstraction, and roles. We take this work one step further by incorporating the needs of groupware programmers into a set of ....

....Though this is not stated explicitly, it is apparent that supporting personalizable groupware is a goal for groupware tools. In addition to the above mentioned goals, some work has also been done in order to investigate what programming complexities are of special concern to groupware developers [54]. As we already mentioned in section 1.4, these complexities are perceived to go along three dimensions: concurrency, abstraction, and roles. Concurrency is needed to ensure that users are not preempted from having continuous access to an application. Abstraction means the logical separation of ....

[Article contains additional citation context not shown here]

John F. Patterson. Comparing the Programming Demands of Single--User and Multi--User Applications. In Proceedings of the Fourth Annual Symposium on User Interface Software and Technology (Hilton Head, Carolina, Nov. 11--13, pages 87--94. ACM, acm press, 1991.

....interfaces. For example, the provision of public and private views, where certain parts of a users interface can be seen only by that user (private or personal) whereas others may be visible by all users (public) Provision of such views permits a control over sharing of information. Patterson [13] states The essence of multi user applications is sharing and control over sharing . Further control over sharing is shown in Grove [4] where a shared view is implemented, as well as a public and private. This view allows a subset of users to access the information held within it. We wish to ....

Patterson, JF. "Comparing the Programming Demands of Single-User and Multi-User Applications". Proc. Symposium on User Interface Software and Technology, Hilton Head, South Carolina, November 1991. Pages: 87-94.

....The flexibility which allows common components to be used in different ways and to different purposes has to be balanced against other criteria such as interoperability, consistency and integration. These issues, of course, are common to software concerns in the design of toolkits for any domain. Patterson (1991) discusses some of the particular issues which CSCW systems raise in comparison with single user interactive systems, focussing in particular on a set of issues addressed in the Rendezvous toolkit, which will be examined shortly. 2.2.2 HCI Issues Flexibility is an important issue in HCI research ....

Patterson, J. (1991). "Comparing the Programming Demands of Single-User and Multi-User Applications", in Proc. ACM Conference on User Interface Software and Technology UIST `91 (Hilton Head, South Carolina).

....users of a program to use different user interfaces 2 to interact with a program. In particular, it should allow users to (a) see different screen images, thereby allowing them to, for instance, scroll to different parts of a document; b) have different access rights, thereby supporting roles [42]; c) have different sets of locks, thereby supporting concurrency control; and (d) interact using different environments, thereby allowing users using different workstations and file systems to collaborate with each other. d Concurrent Scheduling: The framework should allow the modules ....

....analogues of any of the Suite collaboration primitives except the primitives for broadcasting values to all users. On the other hand, it offers overlays, which are not currently supported by Suite. 7.4. Shared Object Systems Multi user programs are also supported by Colab [53] and Rendezvous [41,42], which provide shared object systems for building these programs. Both systems allow the computation and interaction entities of an interactive program to be implemented as a set of communicating fine grained objects and provide mechanisms for keeping objects created for different users ....

[Article contains additional citation context not shown here]

John F. Patterson, "Comparing the Programming Demands of Single-User and Multi-User Applications," Proceedings of the 4th ACM SIGRAPH Conference on User Interface Software and Technology, November 1991, pp. 79-86.

No context found.

Patterson, J. F, Comparing the Programming Demands of Single-user and Multi-user Applications,In Proc.of 4 annual ACM symposium on User interface software and technology, Hilton Head, SC, Nov.1991, pp.11-13.

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J. F. Patterson, `Comparing the programming demands of single-user and multi-user applications', Proc. ACM Symposium on User Interface Software and Technology, Hilton Head, South Carolina, November 1991.

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Patterson, J.F. "Comparing the programming demands of single-user and multi-user applications." Proc. UIST'92 Symposium on User Interface Software and Technology, pages 87-94, Hilton Head, South Carolina, November 11-13 1991. 162

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-249. Patterson, J. F. (1991) Comparing the programming demands of single-user and multiuser applications. In Proceedings of the Fourth Annual Symposium on User Interface Software and Technology (UIST '91), pp. 87-91.

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