Supporting Group Awareness in Collaborative Design Yan Liu, Yuanchun Shi, Guangyou Xu Dept. of Computer Science and Technology Tsinghua University, Beijing, China
[email protected]. edu.cn effect compared with the voice-only mode. On the other hand, from the perspective of social psychology, audio communication is more personal, which is identification of persons could be more easily recognized through audio. Studies on tele-presence found that audio telecommunication could reinforce greatly the sense of being in the same physical space. 9 Video. Although a series of studies showed that video communication does not have apparent improvement on collaboration efficiency than voice-only communication,it could provide more awareness of the presence of others for the participants, especially when new users join in and old users drop out. Also video could transfer more meaningful information, which is obviously observed at communication interval. When participants are contemplating or interacting with computers and do not want to speak, the video channel can deliver the scenery through face expression or gesture, instead of the “silence anxiety” raised by lack of interaction in audio communication. 9 Text. Text-based communication could remove traditional social barrier, the inequity on communication caused by disparity on social status [61. But an obvious deficiency in text-based communication is the difficulty on text interpretation or even misunderstanding due to the lack of video and audio clues, such as face expression, tone, etc. Besides, studies of Ellis&Gibbs [71 showed that for the absence of direct feedback in video and audio communication, text-based communication will be more demanding on coordination, and consensus is usually difficult to be achieved. Similarly, in asynchronous systems, the implementation of group awareness requires certain forms of feedback. Multi-user database systems enforce the illusion of single-user activities for the absence of feedback. In collaborative system, two mechanisms could enhance the group awareness: P Identified locking. In database system, lock mechanism ensures the integrity and consistency of data. But you don’t know who is accessing the locked data and which sort of operation is being executed. Identified locking allows access to the information about the locked object, i.e. who is currently locking the objects and why
Abstract Different from multi-user database management systems, CSCW system must support group awareness explicitly, namely that participants should perceive the presence of each other during the process of cooperating, which is essential to effective collaboration. In this paper we firstly analyze and compare several means of supporting sensibility, then investigate the model of collaborative design and suggest achieving group awareness by product data which forms the foundation of relationship among designers. The infomation model and the shared workspace organization of CECAD (Collaborative Environment for Computer-Aided Design, a prototype system we developed) are presented and its group awareness supporting mechanism is described in succession.
1. Introduction As a sort of multi-user system, CSCW faces issues such as data sharing and multi-user access. In contrast with multi-user database management systems, in which users are isolated by a variety of transparency provided by system and think they are accessing system resources independently, CSCW system must present group awareness explicitly [‘I, to achieve the second C in CSCW, i.e. “Cooperative”. The simplest understanding of group awareness is that one could realize others’ presence in the course of cooperation. This is relatively simple to implement in synchronous systems. However, different means may cause dramatically different effect due to the involvement of social and psychological factors. Generally, Synchronous systems support group cooperation through three categories of media: audio, video and text. 9 Audio. Ochsman& Chapani~’~] in a series of studies investigated the effect of different communication modes in a range of tasks and found that audio is the most essential factor in synchronous communication. In fact, the communication-rich mode, such as face-to-face mode, does not have significantly enhanced communication
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also he need know if the value have been changed and the reason of the change. This is associated with the feature of cooperative design. When several people co-design a product, each will be responsible for different parts or different aspects of one part (appearance, structure, material, etc.), and will set the value of parameters of those parts. Usually these parts are not isolated, but connected in a variety of ways. start
he got the authorization. Given this kind of information, a user may enter into a discussion with the lock holder, and this gives basis for negotiation and possible collaboration. k Event notijication. In database system, data change is invisible to other users. To improve the visibility in collaborative system, event notification mechanism could be used. The initiation of events could be caused by operation to shared object, e.g. the creation or modification of shared object. Response to events could be messages sent to people who will be interested in the event. This article discusses in detail how to support group awareness in cooperative design systems. In section two, we describe a collaborative model in cooperative design and analyze how group awareriess is represented in this model; in reference to the model, we describe how CECAD, a prototype system we developed, supports the implementation of group awareness in its shared workspace. In the final section, we make a brief summary to our work.
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2. CollaborationModel of Cooperative Design In cooperative design, the design process consists of a series of discrete activities. Designers do not always work together and in quite long period they work independently with their own expertise. From the collaborative model in Figure 1, we can see that interaction arise only at the phase of negotiation and evaluation, and the span is very short. During this very short span, designers collaborated in three patterns [’I: k Mutual collaboration, in which participants are “busy working with the other”. k Exclusive collaboration, in which the participants “work on separate parts of the problem, negotiating occasionally by asking for advice from the other”. k Dictator collaboration, where the participants decide who is “in charge” and that person leads the process. Studies show that the “exclusive collaboration” is the most effective pattern and in which they observed most productive results. “Mutual collaboration” led to no result at the end of very busy exchange between the participants, whereas “dictator collaboration” came to a conclusion as soon as the leader made up his mind. So, although “Mutual collaboration’’ exists in cooperative design, such as drafting with whiteboard, we will put the focus on “exclusive collaboration”. “Exclusive collaboration” generally takes place in asynchronous environments, whose interactive pattern is illustrated in Figure 2. Designers browse, operate and store data through access tools, and in many cases, not only does he need know the curTent value of the data, but
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Figure 1. Collaborative model of cooperative design. Design product
Figure 2. Exclusive collaboration pattern. Thus, in cooperative design, group awareness is presented by medium of product data and guaranteed by the following functions of the system: k Designers could access the scheme of product parameters and their underlying rationale, for effective evaluation.
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9 Design object, including function, goal and requirement of the design object 9 Decision, including proposals or positions such as positive or negative position. > Rationale, including design principals, cases, rules and etc. As mentioned in section one, to implement group awareness, certain identification mechanism should be provided when data is accessed and, most importantly, the visibility of data change should be improved. This could be implemented by event and message mechanism. In multi-agent systemL3],designers distribute their design interests through agent interfaces, and each agent maintains a record of interest list. When data changes, the agent will search in its interest list if the data is contained and found, an event will be initiated. In another pattern, the initiation of events and sending of messages are determined by the interdependency among product data. Due to the adjacency or assembly relationship, certain constraint should be satisfied. If one parameter changes, system would judge if it leads to status change of one constraint ('satisfied' or 'not satisfied'), and determine whether to send this event to designers associated with the constraint. We adopt the second pattern in our system, for it represents the relation among designers more directly. Figure 4 is the information model of CECAD. This model describes involved information during design procedure and the diverse and complicated linkage among them. Label 1 indicates the relation of design products, mainly the 'consist-of relation between parent parts and children parts; label 2 indicates the relation of design parameters; Label 3 indicates the 'is-required-by' relation between parameters and their requirements; Label 4 indicates the relations of different proposals, which could be 'support', 'contradict', or 'is-alternative-of; Label 5 indicates the 'is-referenced-by' relation between proposals and their rationale, which could be principals, rules, cases, constraint networks, catalogs and design prototypes. When contradiction occurs and negotiation is required, every involved person would see the underlying rationale in order to make further choice.
9 Designers could access different proposals of the scheme and their rationale, so as to facilitate the reference and coordination. 9 In access to shared data, designers can know its current status, e.g. if the value contradicts with the requirement. 9 When some changes take place to one parameter, designers could sense in some way so as to response appropriately.
3. Organization of shared workspace Shared workspace is a virtual space in which several collaborators work together. In cooperative design it is a platform established on the basis of information model, and designers interact with shared workspace through a range of access tools, including hypertext tool, event management tool, session management tool, negotiation tool, and etc. Figure 3 displayed the organization of shared workspace in CECAD. -------_. --_ Coor di nat or
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Hypertext tool Hypertext permits the browse and generation of nonlinear text. Links in hypertext can express rich connection of information. CECAD uses hypertext as a uniform representation of structure and function of shared information as well as medium of collaboration. We take advantage of hypertext tool to create connection among information conveniently and also browse and update them, e.g. the pertinence of geometric data of design objects. In the phase of negotiation and evaluation, hypertext provides effective mechanism for group awareness. By hypertext, we could view if a design object
Figure 3. Organization of shared workspace in CECAD. Information model There exists a problem of understanding when product data is taken as medium of collaboration in cooperative design. So an appropriate description of information is the foundation of effective evaluation and negotiation. The following layers of information should be described in the information space:
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has different schemes and rationale of these schemes, or if there are different opinions toward a design result, so as to make an effective judgment.
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On account of the rich information maintained in links, interpretation of links is accomplished by linking server in CECAD.
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and the correspondingrole. In addition, roles convey more social information and thus will improve the group awareness during interaction.
Role control Database management systems assign access right to each user, such as view, create, update, delete, etc. However, the mapping of users to rights in this access mode is too simple, and is t:specially inconvenient to cooperative design system in which staffs are always dynamic and their rights are also altered frequently. So, in CECAD, a concept of role is provided, which means rights will not be directly assigned to users but to roles. Users are mapped to roles and gain rights of access to data through roles. So far, roles defined in CECAD are: > Project Manager (PM): to create a project > Responsible (RB):to be responsible for the content of certain objects > Valuator (VA): to be responsible for the evaluation of design result > Coordinator (CO): to be responsible for the procedure of coordination when contradiction takes place. This access mode shows a high degree of flexibility and scalability. When a design system is upgraded, definition of rights will be supplemented or adapted, but the access infrastructure need not be overhauled as long as we redefine the content of role rights or add new roles. When a user changes his work, system would just re-map him
Session management In CECAD, Web is used as a platform for collaboration. Web provides a good environment for cooperation: as a form of data representation, it facilitates browse and operation; as a kind of user interface, its update could be noticed by all users and does not require repeated distribution. In session management, session objects associate workspace with user interface. CECAD will record all the users participating one session and they will see the same interface. As one user operates an object, session object will record the identity of both the object and the user, and make a mapping. When other users operate the same object, they will know how it is being used. Coordination management When contradiction occws, e.g. data value does not satisfy the requirement, or several values do not satisfy certain constraint, notification will be sent to designers by message mechanism and designers may coordinate with
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coordination management tool. Coordination might be carried out in synchronous or asynchronous way. So designers use CAD or other drawing software to work independently on their own task. When negotiation is needed, they enter into the shared workspace and interact with shared data with the tools provided by shared workspace. The information model, which is the kernel of workspace, and a range of tools guarantee the group awareness during the collaboration.
Group awareness is crucial for effective collaboration of multi-users. We do some research in our CECAD. But so far there is few evaluating standard toward group awareness.
5. Reference [l] John A. Martin and Tom Rodden, Cooperative Information Sharing: Developing a Shared Object Service, The Computer Journal, Vol39.No.6, 1996 [2] Maher.M.L., Cicognani.A.,&Simoff.S.J., An experimental study of computer mediated collaborative design, International Journal of Design Computing.,Vol.6, June 1998 [3] Michael P.C. and Stephen C-Y Lu, Discourse Model for collaborative design, Computer-Aided Design,Vol.28, No.5. 1996D333-345 [4] Ochsman.R.B.,& Chapanis.A. The effects of 10 communication modes on the behavior of teams during cooperative problem-solving. Intemational Journal of ManMachine Studies,Vol6, 1974,579-619 [5] Bocker.M., & Miihlbach,L. Communicative presence in video-communication.In Proceedings of the Human Factors and Ergonomics Society 37& Annual Meeting, 1993.Santa Monica, CA: Human Factors and Ergonomics Society. [6] Kiesler.S.,Siegel.J., & McGuire.T.W. Social Psychological aspects of computer-mediated communication. American Psychologist, 39(10),1984, 1123-1134. [7] Ellis, C.A., C3bbs.S.J. & Rein. G.L. Groupware: Some issues and experiences.Communicationsof the ACM. 34(1), 1991,3958 [8] Thomas Kvan, Collaborative Design: what is it? Automation in Construction, Vol. 9,2000,409-415.
4. Conclusion This article aims at providing group awareness in collaborative design system. We analyze collaboration mode of cooperative design and achieving group awareness by product data that forms the foundation of relationship among designers. This article investigates the pertinence of design information, and gives the information model in cooperative design, then on its basis a collaboration platform, i.e. a shared workspace, is constructed. In the workspace, designers use hypertext tool to browse and operate information and, most importantly, through the hyperlink, designers could understand the relation among information which implicates the relation among designers. This provides prerequisite for further collaboration. Session management associates users with shared workspace, and enforces the group awareness using role control and message mechanism. When users operate shared object, according to the relation among information, system will send message or mail to corresponding designers, who can give timely response in reference to the nature of events.
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