The PALIO Framework for Adaptive Information Services Constantine Stephanidis1,2, Alexandros Paramythis1, Vasilios Zarikas1, Anthony Savidis1 1
Institute of Computer Science Foundation for Research and Technology-Hellas Science & Technology Park of Crete Heraklion, Crete, GR-71110, GREECE Tel: +30-810-391741 - Fax: +30-810-391740, Email:
[email protected] 2
Department of Computer Science University of Crete
Abstract This chapter describes the PALIO (Personalised Access to Local Information and services for tourists) service framework, focusing on its extensive support for service adaptation. The PALIO framework is currently used in the development of location-aware information systems for tourists, and is capable of delivering fully adaptive information to a wide range of devices, including mobile ones. Its open and expandable architecture can integrate a variety of pre-existing and forthcoming services, and retrieve information from a collection of different databases. The framework supports dynamic adaptation both in the content and the presentation of information, according to user- and interaction contextcharacteristics. This chapter discusses how the aforementioned adaptation capabilities can support the creation of Multiple User Interfaces (MUIs) on the Web. Keywords: service framework, adaptivity, Web-based information systems, context-based adaptation, multi-device user interfaces
1 Introduction In recent years, the concept of adaptation has been investigated under the perspective of providing built-in accessibility and high interaction quality in applications and services in the emerging information society (Stephanidis, 2001a; Stephanidis, 2001b). Adaptation characterises software products that automatically configure their parameters according to the given attributes of individual users (e.g. mental / motor / sensory characteristics, requirements and preferences), and to the particular context of use (e.g. hardware and software platform, environment of use). In the context of this chapter, adaptation concerns the interactive behaviour of the User Interface (UI), as well as the content of applications and services. Adaptation implies the capability, on the part of the system, of capturing and representing knowledge concerning alternative instantiations suitable for different users, contexts, purposes, etc., as well as for reasoning about those alternatives to arrive at adaptation decisions. Furthermore, adaptation implies the capability of assembling, coherently presenting, and managing at run-time, the appropriate alternatives for the current user, purpose and context of use (Savidis and Stephanidis, 2001).
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The PALIO project 1 addresses the issue of universal access to community-wide services, based on content and UI adaptation beyond desktop access. The main challenge of the PALIO project is the creation of an open system for the unconstrained access and retrieval of information (i.e. not limited by space, time, access technology, etc.). Under this scenario, mobile communication systems play an essential role, because they enable access to services from anywhere and at anytime. One important aspect of the PALIO system is the support for a wide range of communication technologies (mobile or wired) to facilitate access to services. The PALIO project is mainly based on the results of three research projects that have preceded it: TIDE-ACCESS, ACTS-AVANTI, and ESPRIT-HIPS. In all of these projects, a primary research target has been the support for alternative incarnations of the interactive part of applications and services, according to user- and usage context- characteristics. As such, these projects are directly related to the concept of Multiple User Interfaces (MUIs), and have addressed several related aspects from both a methodological and an implementation point of view. The ACCESS project 2 developed new technological solutions for supporting the concept of User Interfaces for all (i.e. universal accessibility of computer-based applications). It facilitated the development of UIs adaptable to individual user abilities, skills, requirements, and preferences. The project addressed the need for innovation in this field and proposed a new development methodology called Unified User Interface development. The project also proposed a set of tools enabling designers to deal with problems encountered while attempting to access technology in a consistent, systematic and unified manner (Stephanidis, 2001c, Savidis and Stephanidis, 2001). The AVANTI project 3 addressed the interaction requirements of disabled individuals who were using Web-based multimedia applications and services. One of the main objectives of the work undertaken was the design and development of a UI that would provide equitable access and quality in use to all potential end users, including disabled and elderly people. This was achieved by employing adaptability and adaptivity techniques at both the content and the UI levels. A unique characteristic of the AVANTI project was that it addressed adaptation both at the clientside UI, through a dedicated, adaptive Web browser, and at the server side, through presentation and content adaptation (Stephanidis et al., 2001; Fink, Kobsa and Nill, 1998). The HIPS project 4 was aimed at developing new interaction paradigms for navigating physical spaces. The objective of the project was to enrich a user’s experience of a city by overlapping the 1
Personalised Access to Local Information and services for tOurists (see Acknowledgments section). TIDE TP1001 - ACCESS “Development platform for unified ACCESS to enabling environments”, funded by the European Commission (1994-1996). The partners of the ACCESS consortium are: CNR-IROE (Italy) - Prime Contractor; FORTH-ICS (Greece); University of Hertforshire (UK); University of Athens (Greece); NAWH (Finland); VTT (Finland); Hereward College (UK); RNIB (UK); Seleco (Italy); MA Systems & Control (UK); PIKOMED (Finland). 3 ACTS - AC042 AVANTI “Adaptable and Adaptive Interaction in Multimedia Telecommunications Applications”, funded by the European Commission (1995-1998). The partners of the ACTS-AVANTI consortium are: ALCATEL Italia, Siette division (Italy) - Prime Contractor; CNR-IROE (Italy); FORTH-ICS (Greece); GMD (Germany), VTT (Finland); University of Sienna (Italy), TECO Systems (Italy); STUDIO ADR (Italy); MA Systems and Control (UK). 4 ESPRIT-25574 HIPS “Hyper-Interaction within Physical Spaces” funded by the European Commission (19972000). The partners of the HIPS consortium are: Universita degli Studi di Siena (Italy) - Prime Contractor; University of Edinburgh (UK); Alcatel Italia SpA (Italy); Istituto Trentino di Cultura (Italy); Cara Broadbent & 2
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physical space with contextual and personalized information on the human environment. HIPS developed ALIAS (Adaptive Location aware Information Assistance for nomadic activitieS), a new interaction paradigm for navigation. ALIAS allowed people to simultaneously navigate both physical and related information space. The gap between the two was minimised by delivering contextualised and personalized information on the human environment through a multimodal presentation, according to the user’s movements. ALIAS was implemented as a telecommunication system that took advantage of an extensive electronic database containing information about the particular place. Users interacted with the system using mobile palmtops with wireless connections or computers with wired connections. (Oppermann and Specht, 1998). PALIO, building on the results of these projects, proposes a new software framework that supports the provision of tourist services in an integrated, open structure. It is capable of providing information from local databases in a personalised way. This framework is based on the concurrent adoption of the following concepts: (a) integration of wireless and wired telecommunication technologies to offer services through both fixed terminals in public places and mobile personal terminals (e.g. mobile phones, PDAs, laptops); (b) location awareness to allow the dynamic modification of information presented (according to user position); (c) adaptation of the contents to automatically provide different presentations depending on user requirements, needs and preferences; (d) scalability of the information to different communication technologies and terminals; (e) interoperability between different service providers in both the envisaged wireless network and the World Wide Web. The framework presented above exhibits several features that bear direct relevance to the concept of MUIs. Specifically, the framework supports adaptation not only on the basis of user characteristics and interests, but also on the basis of the interaction context. The latter includes (amongst other things) the capabilities and features of the access terminals, and the user’s current location. On this basis, the PALIO framework is capable of adapting the content and presentation of services for use on a wide range of devices, with particular emphasis on nomadic interaction from wireless network devices. The rest of this chapter is structured as follows: Section 2 provides an overview of the PALIO system architecture and its adaptation infrastructure. Section 3 discusses the PALIO system under the Adaptive Hypermedia Systems perspective. Section 4 goes into more depth on those characteristics of the framework that are of particular interest regarding MUIs, and presents a brief example of the framework in operation. The chapter concludes with a summary and a brief overview of ongoing work.
2 The PALIO System Architecture 2.1 Overview The Augmented Virtual City Centre (AVC) constitutes the core of the PALIO system. Users perceive the AVC as a system that groups together all information and services available in the Jegher Associes (France); http://www.media.unisi.it/hips
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city. It serves as an augmented, virtual facilitation point from which different types of information and services can be accessed. Context- and location- awareness, as well as the adaptation capabilities of the AVC, enable users to experience their interaction with services as contextually grounded dialogue. For example, the system always knows the user’s location and can correctly infer what is near the user, without the user having to explicitly provide related information. The main building blocks of the AVC are depicted in Figure 1, and can be broadly categorised as follows: The Service Control Centre (SCC) is the central component of the PALIO system. It serves as the access point and the runtime platform for the system's information services. The SCC is the framework upon which other services are built. It provides the generic building blocks required to compose services. Examples include the maintenance of the service state control, the creation of basic information retrieval mechanisms (through which service-specific modules can communicate with, and retrieve information from, various distributed information sources/servers in PALIO), etc. Seen from a different perspective, the SCC acts as a central server that supports multi-user access to integrated, primary information and services; appropriately adapted to the user, the context of use, the access terminal and the telecommunications infrastructure.
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Figure 1: Overall architecture of the PALIO system.
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The User Communication Layer (CL) 5 encapsulates the individual communication servers (Web gateway, WAP gateway, SMS gateway, etc.) and provides transparent communication independent of the server characteristics. This component unifies and abstracts the different communication protocols (e.g. WAP, http) and terminal platforms (e.g. mobile phone, PC, Internet kiosk). Specifically, the CL transforms incoming communication from the user into a common format, so that the rest of the system does not need to handle the peculiarities of the underlying communication networks and protocols. Symmetrically, the CL transforms information expressed in the aforementioned common format into a format appropriate for transmission and presentation on the user’s terminal. In addition to the above, information regarding the capabilities and characteristics of the access terminal propagates across the PALIO system. This information is used to adapt the content and presentation of data transmitted to the user, so that it is appropriate for the user’s terminal (e.g. in terms of media, modalities and bandwidth consumption). The Generic Information Server (IS) integrates and manages existing information and services ( which are distributed over the network). In this respect, the IS acts as a two-way facilitator. Firstly, it assembles appropriate content and data models (in the form of an information ontology and its associated metadata), upon which it acts as a mediator for the retrieval of information and the utilisation of existing services by the Service Control Centre. Secondly, it communicates directly with the distributed servers that contain the respective data, or realise the services. The existing information and services that are being used in PALIO are termed primary, in the sense that they already exist and constitute the building
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The term “layer” is used in the PALIO project for historical reasons; the CL is not a layer in the sense of layered software architecture, but rather a component.
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blocks for the PALIO services. The PALIO (virtual city) services, on the other hand, are synthesised on top of the primary ones and reside within the SCC. The Adaptation Infrastructure is responsible for content- and interface- adaptation in the PALIO System. Its major building blocks are the Adapter, the User Model Server and the Context Model Server. These are described in more detail in the next section.
From the user’s point of view, a PALIO service is an application that can get information on an area of interest. From the developer’s point of view, a PALIO service is a collection of dynamically generated and static template files, expressed in an XML-based, device-independent language, which are used to generate information pages. A PALIO service is implemented using eXtensible Server Pages (XSPs). XSPs are template files written using an XML-based language and processed by the Cocoon 6 publishing framework (used as the ground platform in the implementation of the SCC) to generate information pages that are delivered to the users in a format supported by their terminal devices. If, for example, a user is using an HTML browser, then the information pages are delivered to that user as HTML pages, while if the user is using WAP, then the same information is delivered as WML stacks. A PALIO XSP page may consist of: (a) static content expressed in XHTML, an XMLcompatible version of HTML 4.01; (b) custom XML used to generate dynamic content, including data retrieval queries needed to generate dynamic IS content; (c) custom XML tags used to specify which parts of the generated information page should be adapted for a particular user. In brief, services in PALIO are collections of: -
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Pages containing: static content expressed in XHTML, dynamic content expressed in the PALIO content language, information retrieval queries expressed in the PALIO query and ontology languages, and embedded adaptation rules. External files containing adaptation logic and actions (including files that express arbitrary document transformations in XSLT format). Configuration files specifying the mappings between adaptation logic and service pages. Other service configuration files, including the site map (a term used by Cocoon to refer to mappings between request patterns and actual service pages).
An alternative view of the PALIO architecture is presented in Figure 2. Therein, one can better observe the interconnections of the various components of the framework, as well as their communication protocols. Furthermore, the figure shows the relation between the Cocoon and PALIO frameworks.
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Apache Cocoon is an XML publishing framework that facilitates the usage of XML and XSLT technologies for server applications. Designed around pipelined SAX processing, to benefit performance and scalability, Cocoon offers a flexible environment based on the separation of concerns between content, logic and style–the so-called pyramid model of web contracts. More information can be obtained at the project’s homepage, at: http://xml.apache.org/cocoon/index.html.
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