Showing papers in "Journal of Universal Computer Science in 2012"

A Review of Mobile Location-based Games for Learning across Physical and Virtual Spaces.

Abstract: In this paper we review mobile location-based games for learning. These games are played in physical space, but at the same time, they are supported by actions and events in an interconnected virtual space. Learning in these games is related to issues like the narrative structure, space and game rules and content that define the virtual game space. First, we introduce the theoretical and empirical considerations of mobile location based games, and then we discuss an analytical framework of their main characteristics through typical examples. In particular, we focus on their narrative structure, the interaction modes that they afford, their use of physical space as prop for action, the way this is linked to virtual space and the possible learning impact the game activities have. Finally we conclude with an outline of future trends and possibilities that these kinds of playful activities can have on learning, especially outside school, like in environmental studies and visits in museums and other sites of cultural and historical value.

Discovering Consumer Insight from Twitter via Sentiment Analysis

Abstract: Traditional approaches for studying consumer behavior, such as marketing survey and focus group, require a large amount of time and resources. Moreover, some products, such as smartphones, have a short product life cycle. As an alternative solution, we propose a system, the Micro-blog Sentiment Analysis System (MSAS), based on sentiment analysis to automatically analyze customer opinions from the Twitter micro-blog service. The MSAS consists of five main functions to (1) collect Twitter posts, (2) filter for opinionated posts, (3) detect polarity in each post, (4) categorize product features and (5) summarize and visualize the overall results. We used the product domain of smartphone as our case study. The experiments on 100,000 collected posts related to smartphones showed that the system could help indicating the customers' sentiments towards the product features, such as Application, Screen, and Camera. Further evaluation by experts in smartphone industry confirmed that the system yielded some valid results.

ARLearn: augmented reality meets augmented virtuality

Abstract: Ternier, S., Klemke, R., Kalz, M., Van Ulzen, P., & Specht, M. (2012). ARLearn: augmented reality meets augmented virtuality [Special issue]. Journal of Universal Computer Science - Technology for learning across physical and virtual spaces, 18(15), 2143-2164.

Engineering Security into Distributed Systems: A Survey of Methodologies

Abstract: Rapid technological advances in recent years have precipitated a general shift towards software distribution as a central computing paradigm. This has been accompanied by a corresponding increase in the dangers of security breaches, often causing security attributes to become an inhibiting factor for use and adoption. Despite the acknowledged importance of security, especially in the context of open and collaborative environments, there is a growing gap in the survey literature relating to systematic approaches (methodologies) for engineering secure distributed systems. In this paper, we attempt to fill the aforementioned gap by surveying and critically analyzing the state-of-the-art in security methodologies based on some form of abstract modeling (i.e. model-based methodologies) for, or applicable to, distributed systems. Our detailed reviews can be seen as a step towards increasing awareness and appreciation of a range of methodologies, allowing researchers and industry stakeholders to gain a comprehensive view of the field and make informed decisions. Following the comprehensive survey we propose a number of criteria reflecting the characteristics security methodologies should possess to be adopted in real-life industry scenarios, and evaluate each methodology accordingly. Our results highlight a number of areas for improvement, help to qualify adoption risks, and indicate future research directions.

Co-Designing Collaborative Smart Classroom Curriculum for Secondary School Science

Abstract: This paper introduces a series of iterative designs that investigate how the aggregation and visualization of student-contributed work can support collaborative problem solving in the domain of physics. We investigate how new technologies can enable students to contribute to a shared knowledge base, working across contexts: in class, at home, and in a specialized "smart classroom" environment. We explore how student data can be provided to the teacher before class, in support of planning the next day's lesson, and during class, to help the teacher orchestrate class activities and respond to student needs. Our work builds upon the research tradition of knowledge communities and inquiry learning to inform its design of materials and activities that support productive collaborative interactions for learners. We are also guided by the recent literature on scripting and orchestration to define curricular activities that bridge home and school environments, leveraging a digital platform that includes Web 2.0 features to guide structured collaborations. This paper reports on a design-based research program in which the development of the curriculum and technology platform is informed by successive cycles of design, enactment, analysis, and re-design. The paper will review our efforts through three successive design cycles, exploring the evolution of our own "smart classroom curriculum" for high school physics. For each iteration, we present our design goals, the resulting curriculum and technology, the student learning outcomes, and our evaluation that informs the next iteration. We end with a description of our current design, and discuss the goals and directions of our future efforts.

Accessible Lifelong Learning at Higher Education: Outcomes and Lessons Learned at two Different Pilot Sites in the EU4ALL Project

Abstract: The EU4ALL project (IST-FP6-034778) has developed a general framework to address the needs of accessible lifelong learning at Higher Education level consisting of several standards-based interoperable components integrated into an open web service architecture aimed at supporting adapted interaction to guarantee students' accessibility needs. Its flexibility has supported the project implementation at several sites with different settings and various learning management systems. Large-scale evaluations involving hundreds of users, considering diverse disability types, and key staff roles have allowed obtaining valuable lessons with respect to "how to adopt or enhance eLearning accessibility" at university. The project was evaluated at four higher education institutions, two of the largest in Europe and two medium- sized. In this paper, we focus on describing the implementation and main conclusions at the largest project evaluation site (UNED), which was involved in the project from the beginning, and thus, in the design process, and a medium-sized university that adopted the EU4ALL approach (UPV). This implies dealing with two well-known open source learning environments (i.e. dotLRN and Sakai), and considering a wide variety of stakeholders and requirements. Thus the results of this evaluation serve to illustrate the coverage of both the approach and developments.

A Systematic Review of Information Security Governance Frameworks in the Cloud Computing Environment

Abstract: The senior management of any enterprise that plans to start using Cloud Computing services needs to define a clear governance strategy with regard to the security of its information assets. This paper presents a systematic literature review whose objective is to seek existing Information Security Governance frameworks that may assist companies with these functions. The analysis of the frameworks extracted is complemented with a set of comparative criteria that consider the particularities of Cloud Computing when dealing with security governance issues.

Human and Intellectual Capital Management in the Cloud: Software Vendor Perspective

Abstract: Cloud systems have shifted traditional on-premise software products towards new and service oriented solutions. In order to adapt to this new trend, traditional software vendors are facing a necessary evolution towards service oriented software products. This software evolution is quite complex and full of problems. This paper presents lessons learned and the issues that emerged in a project aimed to adapt Meta 4' PeopleNet solution to adopt a cloud computing approach. This project, designed as a two-step approach, presents a set of issues that are analyzed in this paper, namely: Software evolution, Software processes and Technology and Personnel issues. The resultant conclusions, that highlight the importance of people in this software evolution, are useful for companies facing a product evolution process towards cloud oriented environments.

A Novel Membrane Algorithm Based on Particle Swarm Optimization for Solving Broadcasting Problems

Abstract: This paper presents the application of membrane algorithms to broad- casting problems, which are regarded as NP-hard combinatorial optimization prob- lems. A membrane algorithm, called HPSOPS, is proposed by appropriately combin- ing membrane systems and a hybrid particle swarm optimization with wavelet muta- tion (HPSOWM). HPSOPS is designed with the hierarchical membrane structure and transformation/communication-like rules of membrane systems, the representation of individuals and the evolutionary mechanism of HPSOWM. Experimental results from various broadcasting problems show that HPSOPS performs better than its counter- part HPSOWM and genetic algorithms reported in the literature, in terms of search capability, efficiency, solution stability and precision.

Design-Oriented Pedagogy for Technology-Enhanced Learning to Cross Over the Borders between Formal and Informal Environments

Abstract: In this paper, we introduce an instructional model for technology-enhanced learning in the framework of a design-oriented pedagogy. The model is based on the collaborative designing of learning objects representing real objects in nature and culture environments. Project-based learning, whole task approach, object-oriented learning, multiple perspectives and semantically rich objects constitute the framework for a collaborative design process to articulate, build and share knowledge constructed in a community of learners, teacher and experts with the support of social media and mobile technologies. The co-development process supported by socially shared tools will provide possibilities for working with knowledge objects related to the physical, conceptual or cultural artefacts, so that the constructed learning objects can serve as starting points for others to adapt, integrate and develop them further to represent the phenomenon in question. In the paper, the theoretical background of the pedagogy, the instructional model designed and the development of the model will be introduced. Four design experiments demonstrate the applicability of the model in different educational contexts.

Syntactic and Semantic Extensions to Secure Tropos to Support Security Risk Management

Abstract: The need to consider security from the early stages of the development pro- cess of information systems has been argued by academics and industrialists alike, and security risk management has been recognised as one of the most prominent techniques for eliciting security requirements. However, although existing security modelling lan- guages provide some means to model security aspects, they do not contain concrete constructs to address vulnerable system assets, their risks, and risk treatments. Fur- thermore, security languages do not provide a crosscutting viewpoint relating all three - assets, risks and risk treatments - together. This is problematic since, for a security analyst, it is difficult to detect what the potential security flaws could be, and how they need to be fixed. In this paper, we extend the Secure Tropos language, an agent- and goal-oriented security modelling language to support modelling of security risks. Based on previous work, where we had observed some inadequacies of this language to model security risks, this paper suggests improvements of Secure Tropos semantics and syntax. On the syntax level we extend the concrete and abstract syntax of the lan- guage, so that it covers the security risk management domain. On the semantic level, we illustrate how language constructs need to be improved to address the three dif- ferent levels of security risk management. The suggested improvements are illustrated with the aid of a running example, called eSAP, from the healthcare domain.

Key Person Analysis in Social Communities within the Blogosphere

Abstract: Identifying key persons active in social groups in the blogosphere is performed by means of social network analysis. Two main independent approaches are considered in the paper: (i) discovery of the most important individuals in persistent social communities and (ii) regular centrality measures applied either to social groups or the entire network. A new method for separating of groups stable over time, fulfilling given conditions of activity level of their members is proposed. Furthermore, a new concept for extracting user roles and key persons in such groups is also presented. This new approach was compared to the typical clustering method and the structural node position measure applied to rank users. The experimental studies have been carried out on real two-year blogosphere data.

Multilevel Steganography: Improving Hidden Communication in Networks

Abstract: This paper presents multilevel steganography (MLS), which defines a new concept for hidden communication in telecommunication networks. In MLS, at least two steganographic methods are utilised simultaneously in such a way that one method's (the upper-level) network traffic serves as a carrier for the second method (the lower-level). Such a relationship between two (or more) information-hiding solutions has several potential benefits. The most important is that the lower-level method's steganographic bandwidth can be utilised to make the secret data unreadable even after the detection of the upper-level method, e.g., it can carry a cryptographic key that deciphers the steganogram carried by the upper-level method. It can also be used to provide the steganogram with integrity. Another important benefit is that the lower-level method may be used as a signalling channel to exchange information that affects the way that the upper-level method functions, thus possibly making the steganographic communication harder to detect. A prototype of MLS for IP networks was also developed, and the experimental results are included in this paper.

A Study of the Impact of Global Software Development in Packaged Software Release Planning

Abstract: Today's globalization of software development has its advantages, but also its drawbacks. Software project managers often lead the production of new software versions and their release on the market. This paper analyses the main challenges faced by software product managers in release planning with regard to the adoption of Global Software Development (GSD) practices for developing packaged software. To achieve this objective, two qualitative techniques are used in this study, namely, Focus Group and Delphi Study. The experiment produced two lists, ranking challenges in software release planning. One list was made considering the adoption of GSD practices and the other did not take into account the adoption of these practices. Results show that there are some, apparently solved, challenges for packaged software release planning like "Project monitoring & control" or "Quality management" that become crucial when facing GSD scenarios, while there are other important challenges in traditional software release planning such as "Requirements prioritisation" and "Stakeholders Management" that apparently do not add extra pressure in GSD environments. In sum, GSD is found to be highly influenced by issues concerning personnel and human resources management.

Docs4Learning: Getting Google Docs to Work within the LMS with IMS BLTI

Abstract: Google Docs is a well-known suite of online collaborative tools for document processing, spreadsheets, online presentations, drawing and even forms. The last versions of the major open source LMS Moodle, offers weak integrations with Google Docs treating it as a content repository. But these integrations are neglecting the collaborative qualities of the Google Docs suite and its potential as a learning activity within the LMS course. This paper presents an integration proposal that using the IMS Basic Learning Tools Interoperability (IMS BLTI) standard turns Google Docs into an engine that powers collaborative learning activities within the LMS Moodle.

Aligning Security and Privacy to Support the Development of Secure Information Systems

Abstract: The increasing dependency on information systems to process and manage sensitive information requires the usage of development methods that support the development of secure and private information systems. The literature provides examples of methods that focus on security and privacy individually but fail to provide evidence of information systems development methods that consider security and privacy in a unified framework. Security and privacy are very much related, in particular certain security properties and mechanisms support the achievement of privacy goals. Without a development framework to support developers to explicitly model that relationship, conflicts and vulnerabilities can be introduced to a system design that might endanger its security. In this paper, we present our work in developing a framework that supports the unified analysis of privacy and security. In particular, we present a meta-model that combines concepts from security and privacy requirements methods, such as security and privacy goals, properties, constraints, and actor and process patterns within a social context. A real case study is employed to demonstrate the applicability of our work.

Technology for Learning across Physical and Virtual Spaces.

Abstract: Learning is a process that happens at moments and in spaces that go beyond those typically defined by formal educational institutions. In fact, it is widely recognized that learners’ physical and social interactions with the “real world”, outside the traditional classroom, cannot be neglected when promoting the acquisition of certain skills [Bruce 08]. For example, and within the context of formal education, a visit to a museum could be used for complementing in-classroom learning with situated activities in the “real world”. Additionally, certain current types of widely adopted learning technology such as Virtual Learning Environments (VLEs), or 3D Virtual Worlds (3DVWs), to name a few, have promoted new types of “virtual spaces” for learning (in contrast to the “physical space” of the traditional classroom). These “virtual spaces” provide significant affordances in terms of, e.g., remote interaction and digital content access and distribution, and may also complement and enhance traditional in-classroom learning.

Understanding Microblog Users for Social Recommendation Based on Social Networks Analysis

Abstract: With the rapid growth of Internet and social networking websites, various services are provided in these platforms. For instance, Facebook focuses on social activities, Twitter and Plurk (which are called microblogs) are both focusing on the interaction of users through short messages. Millions of users enjoy services from these websites which are full of marketing possibilities. Understanding the users can assist companies to enhance the accuracy and efficiency of the target market. In this paper, a social recommendation system based on the data from microblogs is proposed. This social recommendation system is built according to the messages and social structure of target users. The similarity of the discovered features of users and products will then be calculated as the essence of the recommendation engine. A case study included in the paper presents how the recommendation system works based on real data from Plurk.

Success Rate of Remote Code Execution Attacks Expert Assessments and Observations

Abstract: This paper describes a study on how cyber security experts assess the importance of three variables related to the probability of successful remote code execution attacks: (i) non- executable memory, (ii) access and (iii) exploits for High or Medium vulnerabilities as defined by the Common Vulnerability Scoring System. The rest of the relevant variables were fixed by the environment of a cyber defense exercise where the respondents participated. The questionnaire was fully completed by fifteen experts. These experts perceived access as the most important variable and availability of exploits for High vulnerabilities as more important than Medium vulnerabilities. Non-executable memory was not seen as significant. Estimates by the experts are compared to observations of actual attacks carried out during the cyber defense exercise. These comparisons show that experts' in general provide fairly inaccurate advice on an abstraction level such as in the present study. However, results also show a prediction model constructed through expert judgment likely is of better quality if the experts' estimates are weighted according to their expertise.

Design Choices Underlying the Software as a Service (SaaS) Business Model from the User Perspective: Exploring the Fourth Wave of Outsourcing

Abstract: Software as a Service (SaaS) can be viewed as the fourth wave of outsourcing. SaaS is a relatively new type of service delivery model in which a service provider delivers its services over the web to many users on a pay per use or period basis. In the scarce literature available, the SaaS business model is almost always analyzed from the perspective of the service provider perspective, and rarely from the user organization. Using the unified business model conceptual framework, two case studies are investigated to understand the design choices underlying the SaaS business model from the user organization perspective. The analyses on the business model dimensions provided insight into the differences between the case studies and helped to identify eight discriminating design choices that are important when designing SaaS business models. These include the (1) SaaS service characteristics, (2) SaaS value source, (3) SaaS user target group, (4) data architecture configuration and tenancy model, (5) SaaS governance and demand/supply management core competencies, (6) cloud deployment model, (7) SaaS integration and provider strategy and the (8) SaaS pricing structure. An appeal is made for more research into the impact of cloud business models.

CC-LO: Embedding Interactivity, Challenge and Empowerment into Collaborative Learning Sessions

Abstract: Despite their demonstrated potential through a range of early studies, on-line collaborative learning systems do not yet have the impact that many believe is possible. In particular, collaborative learning approaches cannot be readily applied to every e-learning experience, since they require a degree of presence and/or collaboration which may be difficult to achieve. In addition, collaborative learning systems often lack the challenging resources and tools required to fully support collaborations, making the experience unattractive to end-users and discouraging progression. Whilst the learner might expect to control the collaborative experience, often it is the collaborative experience that controls and limits the learner. As a result, collaborative learning resources can lack authentic interactivity, user empowerment and balanced levels of challenge, thus having a negative effect in learner motivation and engagement. To overcome these deficiencies, we propose a new paradigm named Collaborative Complex Learning Objects (CC-LO): a special type of Learning Object which aims to leverage the knowledge elicited during live sessions of collaborative learning, augmented with author- generated information, to produce interactive and attractive resources to be experienced and played by learners. During CC-LO execution, learners can observe how avatars discuss and collaborate, how discussion threads grow, and how knowledge is constructed, refined and consolidated. Furthermore, learners can interact with the CC-LO in order to modify some parameters observing the consequences and assessing their understanding. The research reported in this paper was undertaken within the European Framework 7 project ALICE (Adaptive Learning via Intuitive/Interactive, Collaborative and Emotional Systems).

Constructor-based Logics

Abstract: Many computer science applications concern properties that are true for a restricted class of models. In this paper, a couple of constructor-based institutions are presented. These institutions are defined on top of some base institutions, roughly speaking, by enhancing the syntax with constructor symbols and restricting the semantics to models with elements that are reachable by constructors. The proof rules for the constructor-based Horn logics, formalized as institutions, are defined in this paper, and a proof of completeness is provided in the abstract framework of institutions.

PLAYER - a European Project and a Game to Foster Entrepreneurship Education for Young People

Abstract: Entrepreneurship is widely recognized as one of the basic skills to be acquired through a life-long learning. The European Union, under the guidance of the Oslo Agenda, promotes several initiatives to develop entrepreneurship culture in Europe. Education can make a significant contribution to entrepreneurship, encouraging the development of entrepreneurial attitudes and skills in young people. Serious Games are presently recognised as having an important role and potential in education and social networks emerged in the last years as the platform preferred by many, especially young people, to socialize, play games and even learn. This paper presents the PLAYER project, in which a game was developed and implemented as a Facebook application, to enable learning entrepreneurial skills progressively, by guiding users to develop a business idea in the form of a business plan.

Clustering Projects for eLearning Interoperability

Abstract: Since the beginning of the discipline, eLearning has been about innovation. New software, systems, contents and tools are being created and experimented with and in constant evolution. But when systems, contents and tools become successful and part of the regular infrastructure of educational institutions, interoperability becomes an issue. Systems that are consolidated and regularly used need to be able to interoperate with new ones. And the new tendencies need to fit within the current infrastructure. This paper states how several research and development projects with heterogeneous funding sources and locations worldwide, gathered together to find a solution to this common problem, providing open specifications and standards, plus Free/Libre, Open Source reference implementations.

An Exploratory Study of Game-based M-learning for Software Project Management

Abstract: Given that the virtues of m-learning have not yet been fully exploited in teaching Software Project Management (SPM), this paper embarks on a timely endeavour to explore the use of game-based m-learning for SPM by introducing a game called Mobile Application for Project management LEarning (MAPLE). A total of 55 graduate students were invited to participate in the evaluation study carried out for the MAPLE application. The evaluation was based on three design principles derived from the literature, namely, motivation, gaming and learning. Based on the preliminary evaluation, three major observations could be culled. One, game-based m-learning is a useful and an entertaining augmentation to traditional learning. Two, design principles namely motivation, gaming and learning and their appropriate blending is necessary to develop an effective m-learning game. Finally, appealing features in MAPLE are risk alerts, avatar creation and feedback.

SOS: Orchestrating collaborative activities across digital and physical spaces using wearable signaling devices

Abstract: Carrying out collaborative learning activities (supported by technologies or not) typically involves the coordination of multiple participants, in their dynamic assignment to groups and roles and in the distribution of resources and tools to specific group or individuals. While the mechanisms required to address these coordination aspects in digital educational spaces have been largely studied, less research has been conducted on orchestration support for facilitating this coordination in (technology-enhanced) physical spaces, such as the classroom or the playground. This paper presents the Signal Orchestration System (SOS), a system that augments the physical environment with digital signals indicating orchestration aspects. The SOS facilitates its integration with digital educational spaces to allow transitioning activities from digital to physical spaces. The paper describes the SOS system and its underlying architecture through a functional prototype that has been developed to show its feasibility and to enable its evaluation in authentic situations. The main components of the prototype include a Manager, where orchestration visual and auditory signals are configured, changed on the fly and transmitted, and three different designs of Wearable Signaling Devices, which are carried by participants and render the orchestration signals. The prototype has been used in two different experiments in the context of a real course applying adaptations of the well-known Jigsaw collaborative learning flow pattern. The results show that the SOS enables a flexible dynamic orchestration of the collaborative activities.

Adaptive Group Key Management Protocol for Wireless Communications

Abstract: Group-oriented services and wireless communication networks are among the emerging technologies of the last few years. Group key management, which is an important building bloc in securing group communication, has received a particularattention in both academic and industry research communities. This is due to the economical relevance of group-based applications, such as video on demand, videoconferencing, collaborative work. The key management concerns the distribution and updates of the key material each time a member joins or leaves the group. The dynamic aspect of group applications due to free membership joins and leaves in addition to members' mobility makes difficult the design of efficient and scalable key management protocols. Indeed, to secure group communication in mobile environment, the protocol must deal not only with dynamic group membership but also with dynamic member location. Thus, the challenges in designing secure and scalable key management protocols are: the dynamic updates of the key caused by frequent joins and leaves, the large size of the group and the mobility of group members. Many academic researches have addressed the first and the third challenges. However the mobility challenge has not been widely addressed. In this paper, we present our solution for group key management with a mobility support. Our protocol focuses on the above three challenges. It is highly scalable to dynamic groups and treats the nodes' mobility with a null re-keying cost and keeps perfect backward and forward secrecies. Our simulation studies show that our protocol makes better performance compared to other protocols while reducing the overall overhead and the number of re-keying messages and has no security failures.

Risk-driven security metrics in agile software development: An industrial pilot study

Abstract: The need for effective and efficient information security solutions is steadily increasing in the software industry. Software and system developers require practical and systematic approaches to obtain sufficient and credible evidence of the security level in the system under development in order to guide their efforts and ensure the efficient use of resources. We present experiences of developing and using hierarchical security metrics and measurements in an industrial pilot study at Ericsson Finland. The pilot focused on risk-driven security design and implementation in the context of an Agile software development process. The pilot target was a well-established telecommunications product of Ericsson and a core component in modern mobile networks. The results of the study demonstrate the practical potential of risk-driven security metrics, particularly in offering some early visibility of security effectiveness and efficiency. Hierarchical metrics models enable the linking of security objectives with detailed measurements. Security metrics visualization was found to play a crucial role in increasing the manageability of metrics. We also found that the practical means of managing larger collections of metrics and measurements are more essential than individual security metrics. A major challenge in the use of risk-driven security metrics is the lack of evidence for security effectiveness evidence in the early phases of product development and Risk Analysis, when the needs for it are at their greatest.

The Method of Logistic Optimization in E-commerce

Abstract: Rapidly changing business environment requires new approaches and methods for supporting management systems in all types of companies. Modern companies doing business use e-commerce systems by default. One of the key areas of e-commerce systems is logistics and the supply chain. The optimal way to ensure the success of logistics and supply chains is to use the methods of modeling and simulation based on appropriate models and especially its mathematical representation. In this paper, authors highlight the customer-oriented model of the e-commerce system and deal with logistic optimization and simulations. As an example, a sample logistic structure which requires the adequate control approach is presented. This is realized by means of heuristic algorithms which are responsible for meeting the set criterion. Moreover, the criteria to either maximize the production output or minimize the lost flow capacity of the logistic system or minimize the tool replacement criterion are introduced. Equations of state are given in order to represent the flow of material through the logistic system.

A Metropolitan Taxi Mobility Model from Real GPS Traces

Abstract: The past few years have witnessed the growing interest in vehicular ad hoc networks (VANETs) and their potential applications for Internet of Things (IoT). Since the mobility model is crucial to simulation based researches of VANET, using a realistic mobility model can ensure the consistency between simulation results and real deployments. Although there are many mo- bility models characterizing the movement of mobile nodes, none of them consider the behavior of vehicles in a metropolitan scenario. In this paper, we present our study of extracting a mobility model for VANET from a large amount of real taxi GPS trace data. In order to capture charac- teristics of the urban vehicle network from microscopic to macroscopic aspects, we design three parameters and extract their values from the GPS trace data. Using this mobility model, we can generate the synthetic trace to simulate the movement of taxis in the urban area of a metropolis. The validation is carried through extensive comparisons between the synthetic trace and the real trace. The results show that our mobility model has a good approximation with the real scenario.