Towards the OWLA methodology for development of Open, Web/Wireless and Adaptive hypermedia information systems. Toni Alatalo
Mikko T. Siponen
University of Oulu, Finland E-mail:
[email protected]
University of Oulu, Finland E-mail:
[email protected]
ABSTRACT
This paper presents the work done in project OWLA for a development methodology, focusing on Web-based and mobile-aware, open and adaptive hypermedia information systems. As the existing development methodologies do not support the additional requirements for adaptivity, such as personalization, and mobile-use, new methods for designing are proposed. Openness (related to interoperability) and the Internet-environment present challenges for security, which is part of the overall methodology as well. By addressing these aspects (mobility, adaptivity and security), the methodology fragments are meant to complement the existing approaches for designing hypermedia and information systems. Preliminary experiences of our approach are consired. KEYWORDS: methodology, web information systems,
adaptive hypermedia, mobile-aware, information security INTRODUCTION
Web development has been said to be in a similar crisis that occurred in software development in the 1970’s, and to overcome this crisis, more disciplined development methodologies have been called for [24, 7]. Most Web development can be described as ad-hoc, where no methodologies are (consciously) used. Also, the traditional methods from software engineering to user interface design, are sometimes applied as such in Web development. To meet the special challenges of hypermedia development, several approaches have been proposed, such as RMM, OOHDM, WebML and OO-HMethod [24, 6, 14]. These approaches are mostly based on combining Web- and/or hypermedia specific aspects with traditional software engineering, which is encountered with several criticisms. On one hand, the advocates of so-called lightweight methods, such as eXtreme Programming, have claimed that much of the software engineering legacy is too heavy in its' procedures, insufficiently flexible and not suitable for the varying customer requirements and qualities of the Space for ACM copyright information. Remember to delete this before submitting final version. (Use a column break in MS word to stop text from overwriting this area.
development teams [28]. On the other hand, from an information systems (IS) point of view, the focus on the technical/functional aspects of software and applications does not help to understand them in wider organizational contexts [17]. For example, the notations do not serve as communication tools between developers and users. Then again, methodological development in an organization may be but façade, treated as “a necessary fiction” detached from the actual work [26]. In addition to the requirements for development methodologies in general (as discussed widely in information systems and software engineering literatures), there are special requirements for Web developments methodologies. Of these the requirements for basic and advanced hypermedia functionality [6], hypermedia communication environments, adaptive and mobile hypermedia have been analyzed in [27]. These further requirements do not help to achieve what methodologies are called for, e.g. mainly the control over the development process, but come from a user centered point of view, in order to include what is required for advanced application features within the process. We refer to the engineering approach by Lowe&Hall (25) as a basis for a disciplined hypermedia and Web development methodology, and in order to study it, put it to practice (combined with OOHDM [30]) early on in the project [1]. In the following sections, this paper presents the issues rised by the themes within the focus of the project: 1. mobility 2. adaptivity and 3. security. Then issues related to achieving a unified approach, and some considerations about development processes, are discussed, Finally the work done so far is concluded and future work projected in the end. MOBILITY
The mobile world of mobile phones, palmtop computing and other emerging wireless information and communication technologies as an environment for the Web is different from the current desktop platforms, or the envisioned digiTV enchanced livingrooms for that matter. This variety has to be understood if services for it are to be designed, leading to methods and tools for the actual work. This includes understanding the usage of different terminals, interface design for small screen etc. but also analysing the potential advantages of mobile technologies over traditional ones, e.g.
physical positioning. It is yet not known whether this actually changes the development process itself – that is yet something to study. One of the key elements in mobile-aware hypermedia is adapting to users' situations, but somewhat differently than in the traditional user-modelling centric view of adaptive hypermedia. Design of mobile applications often aims to context-awareness, the ability of application to extract, interpret and use situational information and adapt functionality to the current context of use. Examples of context information are [21]: identity, spatial information, temporal information, environmental information, social situation, availability of resources, physiological measurements, activity and schedules and agendas. A concise overall definition: "context is everything but the explicit input and output" (e.g. the states that effect the application's behaviour) is given in [22]. It has been suggested that the design of context - i.e. considering context as the object of a design activity -would be "a natural extension of current approaches that treat context as information for the design of the artifacts (design with context) or as the scenario for enacting the design activity (contextual design or design in context)" [29]. We share this interest, and
therefore focus on the design phase that occurs after early analysis and requirements elication, trying to come up with ways to model specifications for actual implementations with the richness of information that can be found surrounding the use. An example of designing new navigational structures for an existing Web service, with the mobile use in mind, using our previously presented modelling method for designing adaptive hypermedia is in the specifications is presented in [3]. ADAPTIVITY
De Bra et al [10] define adaptive hypermedia as a collection of nodes and links, that is accompanied by user profiles, which are used to adapt the presentation. Also Brusilovsky [8], in his authoritative definition, specifies having a user model as the criteria for a hypermedia system to be adaptive. In our research, we attempt to approach the issue more broadly. For adaptivity in a broad sense, there are many ways of looking at it: personalization, contextualization, customization and even reusability. The big picture can be divided in two main categories: 1. adapting to change 2. adapting to difference. For a theoretical underpinning on time (temporal) and difference (spatial) based variance see [16]. An early version of our conceptualization about the issue is presented in the following, and will be elaborated in future research. Adapting to change
By adapting to change we mean situations where the conditions of the hypermedia system change in a way that requires change in the behavior, or even the whole structure of the system. The change is related to time, i.e. the situation
at one time may turn out to be different some time in the future. Concerning the three levels of information systems development introduced in [17], this kind of change may occur on 1. the organizational level, e.g. in the requirements set for the system by users, 2. the infological level (content and functionality) or 3. the technological level. These points are elaborated brieffly in the following. Organizational change. For situations when there is
dramatic change in the organizations where the information systems are used, it has been argued that the traditional development methods (that assume a relatively static situation) do not apply [34]. Claiming that in such situations the traditional goals for development are obsolete, the authors state: "Lengthy analysis and design are poor investments", "Abstract requirements are largely imaginary" and even "Complete and unambiguous specifications are ineffectual". Consequently, their advice goes as follows: "Systems should be under constant development, can never be fully specified and are subject to constant adjustment and adaptation" [34]. This of course is in direct conflict with much of methodologies - including the Hypermedia & the Web Engineering approach by Lowe&Hall [25] - but a great motivation for serious adaptivity research! Dynamic information. The infological level is what adaptive
hypermedia is usually about - i.e. the adaptivity of nodes and links (or content and functionality). This includes a great amount of issues, from self-adapting web sites to tools the users may have to adapt (or change) the content. Our work is mostly focused on this level. Implementation. On the technological level is the actual
implementation of the hypermedia information system. Adaptivity to change in technology refers to programming and computer platforms, which are outside our core focus. An interesting approach, however, is the Demeter method for adaptive programming [23]. Also regarding mobile computing, the constantly changing technologies (protocols etc.) present challenges. Adapting to difference
Another kind of adaptivity dealt with here is adapting to difference. Unlike adapting to change, adapting to difference is not (necessarily) related to time, but is concerned with adapting to conditions that occur at the same time but in different situations. For example, personalization is adapting to different persons, i.e. users, so that the system may appear different for different users at the same time. Other examples of adapting to difference include adapting to different use devices, and locations / contexts / situations of use and different needs and tasks at hand. Elaborating the analysis of this type of adaptivity with respect to the three levels of information systems development is left for future. Adapting to difference is, however, what usually is meant by adaptivity in hypermedia and also the focus of our contributions so far - a closer examination follows. Designing adaptivity to difference
An overall analysis of modelling adaptivity (there:
customization) from a requirements perspecive is presented in [19], including the analysis, design and implementation phases of development. Also, the adaptive hypermedia design method (AHDM) supports adaptive hypermedia by including the design of user models within the methodology [20]. The existing methodologies do not, however, support the modelling of adaptivity dependencies when specifying the content and functionality of the hypermedia application. That is, there are no means for the designer to visualize e.g. how certain features of the system depend on certain properties of the user. We have presented a modelling method for adaptive hypermedia, proposing a solution to that problem [2]. The proposal is preliminary, but has been tested internally by the project members, also for adapting to mobility as mentioned in the previous section. A brief summary of the approach follows. The modelling method under development is based on an adaptation concept which we call structural adaptation. Structural adaptive system consist of three parts (or group of system components), namely Adaptors, Heuristics, and Transformants. They can be understood as specific roles some objects in the system have with respect to adaptivity.
user
device data
Adaptors … event
links
Heuristics shadow s
context s
data
Transformants …
transitions method s
Figure 1. Parts of an adaptive hypermedia system. Adaptors are defined as a system components to which the rest of the system adapts. In harmony with the object oriented design each adaptor consist of attributes, known as adaptor’s properties, and methods. Adaptor’s properties play an important role in the adaptation, since they determine relations between adaptors and system’s adaptive components, as defined by heuristics. Transformants are the name for system’s adaptive components. They adapt to adaptors according to heuristics. Transformants are class, attribute and method constructs containing conditional and non-conditional assosiations. According to transformant structure it can consist of nonadaptive parts (uses non-conditional assosiations), known as the skeleton, and adaptive parts (uses conditional assosiations). Heuristics defines two-fold relations between adaptors and transformants: a) to which adaptor's properties transformant has relation to (disclosed with variables) and b) what is the nature of the relation (mathematical and logical dependency). Heuristics, which are modeled with shadows, can be classified based on adaptors to which the heuristic rule is mainly involved. The shadow consists of one clause (heuristic rule), containing variables, constants,
mathematical- and logical operands, which defines the relation of one or several adaptors and transformants. As a result of this each shadow has a binary output value, 0 (false) or 1 (true), which indicates adaptor's adaptive part's inclusion or disjunction. In other words, shadows acts as a logical glue which holds the transformant’s skeleton and adaptive parts together. In our internal tests, we have used this approach to complement the UML-based notation [15] for the OOHDMlike modelling [30]. A remaining issue is the relation of our approach to related ones, such as the Adaptive Hypermedia Architecture Model [10]. SECURITY
The existing approaches for designing secure IS/software [see 4, 13, 31] lack a comprehensive modeling support [31, 32]. The different IS security approaches cover the different levels of IS, but no single method provide a comprehensive modeling support. Yet, many of the existing approaches can not be integrated into IS or software development methods, leading to the problem of developmental duality. Moreover, the existing approaches restrict the autonomy of developers to use the approaches they prefer. Finally, IS development methods are known to be emergent and evolving [35]: novel methods arise every now and then, and are modified by practitioners to fit different situations [18]. The same goes for IS security methods [5]. However, it is difficult to put forth one universal security method that will match every existing, forthcoming and unpredictable IS development methods and they permutations. A meta-level viewpoint is one way to address the aforementioned concerns. With respect to the problem concerning a lack of comprehensive modeling support by existing single methods, we propose a meta-notation which provides modeling support for different levels of IS. The same goes for the lack of methodological support for security aspects of hypermedia IS. The solution avoids the problem of developmental duality. This meta-notation including five dimensions: security subjects, security objects, security constraints, security classifications, and security policy - can be added to the any existing notation for modeling IS or software. Given that one wants to avoid the problem of developmental duality, it is impossible to provide security specific notation (excluding the metanotation that can be applied to different, if not all, existing modeling notations). Security specific notation would inevitably lead to the problem of developmental duality. Such security specific notation cannot be used to model normal IS development, as security development and normal IS or software development would be carried out using different methods. However, any introduction of a new method, which includes both normal and security development, would restrict the autonomy of developers to use the approaches they prefer (they would have to use this particular approach and in all likelihood abandon their "old" methods/practices). This proposed solution facilitates the developers autonomy: developers can use the methods they prefer as a basis of development. This part of the
preliminary OWLA approach is presented in [33]. DISCUSSION
Of the wide range of issues related to methodology development, two points are selected for discussion here: the various approaches to design and danger of developmental duality, and process considerations (otherwise the work presented here addresses modelling issues only).
REFERENCES
1. Alatalo, T. (2001) Lessons learned from putting a Web engineering approach to practice. The 24th Information Systems Research Seminar in Scandinavia, Ulvik in Hardanger, Norway, 11-14 August 2001. 2. Alatalo, T. & Peräaho, J. (2001a). A Modelling Method for Designing Adaptive Hypermedia. A position paper at the Third Workshop on Adaptive Hypertext and Hypermedia, UM2001 session.
Additional requirements and developmental duality
Introducing advanced hypermedia features (aka. hypertext functionality), support for mobility and adaptivity into development methodologies may present the problem of developmental duality, which was already addressed in the security section, in yet unencountered ways. There is no point in developing with only one focus in mind, but the issues presented here should be understood as some of the various aspects (potentially) required in development. Arguably, the proposed method for designing adaptivity which has also been used to design mobile-aware (contextual) hypermedia - can be seen as a meta-level solution, introducing meta-notation in form of recognizing the objects of modelling for adaptivity (adaptors, heuristics, transformants) similarly to the meta-notation for security (security subjects, objects, constraints, classifications and policy). Clearly, deepening the understanding on these issues and formulizing a more unified solution in the future is needed. Process considerations
3. Alatalo, T. & Peräaho, J. (2001b). Designing Mobileaware Adaptive Hypermedia. A position paper submitted to the Third Workshop on Adaptive Hypertext and Hypermedia, HT2001 session. 4. Baskerville, R., (1993), Information Systems Security Design Methods: Implications for Information Systems Development. ACM Computing Surveys 25, (4) December, pp. 375-414. 5. Baskerville, R. & Siponen, M.T. (2001): An Information Security Meta-policy for Emergent Organizations. Journal of Logistic Information Management, special issue on Information Security. 6. Bieber, M., Vitali, F., Ashman, H., Balasubramanian, V. & Oinas-Kukkonen, H. (1997). Fourth Generation Hypermedia: Some Missing Links for the World Wide Web, International Journal of Human Computer Studies, 47(1), 31-65.
Besides modelling, which has been a central part of our work so far, an important part of a methodology is the process model. Examples of commond process models are the so-called waterfall and spiral models. Our methods have been factored so, that they would fit basically in any process. This is consistent with the requirement for flexibility in methodologies, but has not been put to true test yet.
7. Brereton, O. P., Budgen, D. and Hamilton, G. (1998) Hypertext: the next maintenance mountain, IEEE Computer Vol. 31, No. 12, December 1998, pp 49-55
CONCLUSIONS AND FUTURE WORK
9. Ceri, S., Fraternali, P., Bongio, A.: Web Modeling Language (WebML): a modeling language for designing Web sites. WWW9 Conference, Amsterdam, May 2000.
The work done in project OWLA, aiming at a development methodology focusing on Web-based and mobile-aware services as open and adaptive hypermedia information systems, was described in this paper. New methods for designing were proposed, as the existing development methodologies do not support the additional requirements for adaptivity, mobile-use and security. These aspects complement the existing approaches for designing hypermedia and information systems. Preliminary experiences of our approach were consired, and more is expected from the research to be done in the future, when the parts of our approach will be tested empirically using actions research as the research method. A great challenge is unifiying the different aspects into an overall approach. ACKNOWLEDGMENTS
Acknowledgements to Seppo Pahnila for helpful comments.
8. Brusilovsky, P. (1996). Methods and Techniques of Adaptive Hypermedia. User Modeling and UserAdapted Interaction, Vol. 6, pp. 87-129, Kluwer academic publishers.
10. De Bra, P., Eklund, J., Kobsa, A., Brusilovsky, P., Hall, W. (1999). Adaptive Hypermedia: Purpose, Methods, and Techniques. The 10th ACM Conference on Hypertext and Hypermedia, Hypertext ’99. 11. De Bra, P., Houben, G. J., Wu, H. (1999). AHAM: A Dexter-based Reference Model for Adaptive Hypermedia. The 10th ACM Conference on Hypertext and Hypermedia, Hypertext ’99. 12. De Troyer, O. M. F. & Leune, C. J. 1998. WSDM : A user-centered design method for web sites. In Proceedings of the Seventh International World Wide Web Conference, 1998
13. Dhillon, G. and Backhouse, J., (2001), Current directions in IS security research: toward socioorganizational perspectives. Information Systems Journal. Vol 11, No 2. 14. Gómez J., Cachero C. and Pastor O. 2000. Extending a Conceptual Modelling Approach to Web Application Design. B. Wangler, L. Bergman (Eds.): CAiSE 2000, LNCS 1789, pp. 79-93. Springer-Verlag Berlin Heidelberg. 15. Hennicker, R. & Koch, N. (2000). A UML-based Methodology for Hypermedia Design. In A. Evans, S. Stuart, and B. Selic, editors, UML'2000 - The Unified Modeling Language - Advancing the Standard, volume 1939 of Lecture Notes in Computer Science, York, England, October 2000. Springer Verlag. 16. Heylighen, F. (1991). Modelling Emergence. World Futures, 31:89-104, 1991. 17. Iivari, J. "Levels of abstraction as a conceptual Framework for an Information System", in E. D. Falkenberg & P. Lindgren (eds), Information System Concepts: An In-depth Analysis, North Holland, pp 323352, 1989. 18. Jaaksi, A. (1998) A method for your 1st object-oriented project. Journal of Object-Oriented Programming, pages 17-25, January 1998. 19. Kappel, G., Retschitzegger, W. & Schwinger, W. (2000) Modeling Customizable Web Applications - A Requirement's Perspective. 2000 Kyoto International Conference on Digital Libraries: Research and Practice, November 13th -16th, 2000 20. Koch, N. (1998). Towards a Methodology for Adaptive Hypermedia Systems Development. In Adaptivität und Benutzermodellierung in interaktiven Softwaresystemen, Proceedings of the 6th Workkshop, ABIS-98, U. Timm and M. Roessel (Eds.)
Development Methodologies: Help or Hindrance? WebNet Journal. July-Sept. 1999. 25. Lowe, D. & Hall, W. (1999). Hypermedia & the Web. Chichester: John Wiley & Sons. 26. Nandhakumar, J. & Avison, D. E. (1999). The fiction of methodological development: a field study of information systems development. Information Technology & People, Vol. 12 No. 2, pp. 176-191. 27. Oinas-Kukkonen H., Alatalo T., Kaasila J., Kivelä H. & Sivunen S. (2001) Requirements for Web Information Systems Engineering Methodologies. In M. Rossi & K. Siau (editors): Information Modelling in the Next Millenium, Idea Group Publishing, 2001. 28. PortlandPatternRepository (2001) BigDesignCritique. 29. Roque, L. & Almeida, A. (2000) Towards the Design of Context. CHI 2000 Workshop Research Directions in Situated Computing. 30. Schwabe, D. & Rossi, G. (1998). Developing Hypermedia Applications using OOHDM. Workshop on Hypermedia Development Processes: Methods and Models, Hypertext'98. 31. Siponen, M.T., (2001a), An analysis of the recent IS security development approaches: descriptive and prescriptive implications. In: G. Dhillon (eds:) Information Security Management - Global Challenges in the Next Millennium, Idea Group (2001). 32. Siponen, M.T. (2001b): A Paradigmatic Analysis of Conventional Information security management/Development Approaches: Implications for Research and Practice. 6th International Conference on Information Security, 11-13 June 2001, Paris, France.
21. Korkea-aho, M. (2000). Context-Aware Applications Survey.
33. Siponen, M.T. & Baskerville, R., (2001): A New Paradigm For Adding Security Into IS Development Methods. Submitted to 8th Annual Working Conference on Information Security Management & Small Systems Security Las Vegas, NV, USA, September 27-28, 2001.
22. Lieberman, H. & Selker, T. (2000) Out of Context: Computer Systems that Adapt To, and Learn From, Context. CHI 2000 Workshop Research Directions in Situated Computing.
34. Truex, D. P., Baskerville, R. & Klein, H. (1999). Growing Systems in Emergent Organizations. Communications of the ACM, August 1999 Vol. 42 No. 8
23. Lieberherr, K. (1996) Adaptive Object-Oriented Software: The Demeter Method. PWS Publishing Company.
35. Truex, D.P., Baskerville, R. & Travis, J. (2000). Amethodical systems development: the deferred meaning of systems development methods. Accounting, Management & Information Technologies, 10, 2000.
24. Lowe, D. (1999) Engineering the Web - Web
