A Semiautomatic Content Adaptation Authoring Tool for Mobile Learning 539 5 Conclusion and Future Work In this paper, we develop a web-based content adaptation tool that focus on adapting html-based learning materials composed of texts and images. Instead of real-time adapting general Web pages on Internet, we believe automatic and manual adapta- tions are equally important for learning contents. Authors can not only utilize the proposed adaptation templates automatically and efficiently to adapt the learning content for handhelds but also adjust the template parameters to influence the adapted result, as well as the educational quality is assured by authors themselves. Although, the mobile devices are becoming more and more powerful, there still have been a lot of various multi-media resources cannot be properly displayed such as Flash files and specific format videos. As a result, how to adequately adapt or represent the multi- media resources included in learning contents is one of our future works. Another primary future work is combining an adaptive content delivering system with our authoring tool that has the perception of learners’ platforms. Utilizing the context-aware technology, the server can correctly delivering the required and corre- sponding course package to learners as shown in figure 8. The Common Cartridge packages with multi-version courses created by our pro- posed authoring tool are stored in a course repository. The LMS filters the request and decides whether delivering the content to the learner’s learning platform. The LMS will send a message to strongly suggest the user canceling the learning request if no corresponding version exists in this course. The advantage of the architecture is that the course package is assured by the author, and some content should never been displayed on specific devices even after the adaptation process. As a result the learner will never waste the significant time and bandwidth to download an appropriate course for their learning platforms. References 1. ADL SCORM 2004 Documentation (2005), http://www.adlnet.org 2. IMS Common Cartridge, http://www.imsglobal.org/commoncartridge.html 3. Katz, R.H.: Adaptation and mobility in wireless information systems. IEEE Personal Communications 1(1), 6–17 (2004) 4. Kindberg, T., Fox, A.: System software for ubiquitous computing. In: IEEE Pervasive Computing (January 2002) 5. Chen, Y., Ma, W.Y., Zhang, H.J.: Detecting web page structure for adaptive viewing on small form factor devices. In: WWW 2003: Proceedings of the 12th international confer- ence on World Wide Web, pp. 225–233 (2003) 6. de Lara, E., Wallach, D.S., Zwaenepoel, W.: Puppeteer: Component-based adaptation for mobile computing. In: Proceedings of the 3rd USENIX Symposium on Internet Technolo- gies and Systems (March 2001) 7. Ramaswamy, L., Iyengar, A., Liu, L., Douglis, F.: Automatic detection of fragments in dynamically generated web pages. In: WWW 2004: Proceedings of the 13th international conference on World Wide Web, pp. 443–454 (2003) 540 H P. Chang et al. 8. Kaasinen, E., Aaltonen, M., Kolari, J., Melakoski, S., Laakko, T.: Two Approaches to Bringing Internet Services to WAP Devices. In: Proceedings of the 9th WWW Conf., pp. 231–246 (2000) 9. WAP Forum. Wireless application protocol architecture specification (April 1998), http://www.wapforum.org/what/technical/arch-30-apr-98.pdf 10. Han, R., Bhagwat, P., LaMaire, R., Mummert, T., Perret, V., Rubas, J.: Dynamic adapta- tion in an image transcoding proxy for mobile web browsing. IEEE Personal Communica- tions 5(6), 8–17 (1998) 11. Narayanan, D., Flinn, J., Satyanarayanan, M.: Using history to improve mobile application adaptation. In: Proceedings of the 3rd IEEE Workshop on Mobile Computing Systems and Applications (December 2000) 12. Hwang, Y., Kim, J., Seo, E.: Structure-Aware Web Transcoding for Mobile Devices. In: IEEE Internet computing, pp. 14–21 (2003) 13. Kärkkäinen, L., Laarni, J.: Designing for Small Display Screens. In: Proceedings of the 2rd Nordic conference on Human-computer interaction, pp. 227–230 (2002) 14. Buyukkokten, O., Kaljuvee, O., Garcia-Molina, H., Paepcke, A., Winograd, T.: Efficient Web Browsing on Handheld Devices Using Page and Form Summarization. ACM Trans- actions on Information Systems, 82–115 (January 2002) 15. Mohomed, I., Cai, J.C., Chavoshi, S., de Lara, E.: Applications: Context-Aware Interactive Content Adaptation. In: Proceedings of the 4th international conference on Mobile sys- tems, applications and services MobiSys., pp. 42–55 (2006) F. Li et al. (Eds.): ICWL 2008, LNCS 5145, pp. 541–551, 2008. © Springer-Verlag Berlin Heidelberg 2008 An Optimized Scheme for Mobile Learning on IP-Based Network Using SIP Shaojing Fan, Jianbo Fan, Yongping Zhang, and Zhongkun He College of Electron & Information Engineering, Ningbo University of Technology, Ningbo, Zhejiang 315016 China {fsj,jbfan,ypz,hzk}@nbut.cn Abstract. With the fast development of wireless technology, the concept of e-learning has been constantly evolved into mobile learning(m-learning), which means to use mobile technologies to enhance the learning experience by blend- ing mobile terminal devices and network to engage and motivate learners at any time and anywhere. However, current m-learning systems are mainly based on HTTP, which is static and limits in Web access, thus are insufficient in support of the various new mobile devices and wireless access methods. SIP(Session Initiation Protocol) is a signal protocol with excellent mobility support on both personal and service levels. The key reasons for SIP's popularity as a protocol for mobile applications are discussed in this paper. An optimized m-learning system architecture based on SIP is proposed. The mobility support of the m-learning system based on the new architecture is presented. Tests show that the new system is dynamic and mobile, with high performance in real time con- nection and interactivity. Keywords: SIP, e-learning, m-learning, mobility. 1 Introduction The WWW and other IP-based collaborative tools have significantly enhanced the ability to train and educate electronically. A web course, having a teacher and regis- tered group of students, brings together a community of learners into a virtual edu- cational environment where they can view course contents and interact with each other [1]. At the present age, with the increasing use of mobile devices and wireless networks, there will be more requirements for new models of mobile learning and teaching. Meanwhile, most of the courseware online are simply HTML files shifted from textbook, or PowerPoint, doc files that can be downloaded onto local server. This is obviously not compatible with the rapid development of multimedia tech- nology, which enables teachers to use live and vivid multimedia courseware and other teaching materials. SIP is a signal protocol that is designed for multimedia communications sessions with great mobility support [2]. In this paper we will dis- cuss the application of SIP in m-learning systems. Our goal is to find an optimized scheme for mobile multimedia teaching using SIP. 542 S. Fan et al. 2 Background on M-Learning and SIP 2.1 Attributes of M-Learning M-learning is a natural extension of e-learning. It can be defined as learning that is mediated by mobile devices such as mobile phones, personal data assistants, hand- helds, wearable devices and laptops. M-learning has made an exponential leap from theory explored by academicians to a real contribution to learning in a short span of years. The heightened interest in m-learning can be attributed to the following three main factors: First, there are more wireless networks, services, and devices than ever before. Us- ing mobile devices like cell phones, PDAs, and laptops becomes more commonplace. People are increasingly connected and are digitally communicating with each other in ways like GPS, Wi-Fi, and 3G. It is certainly reasonable to use the wireless technolo- gies for improving learning, teaching, and research processes. Second, people want “anytime, anywhere” connections to be educated more than ever before. With the rapid development of world economy, more people are feeling higher pressure on self-education. Demands for resource, instruction, training, and education anytime and anywhere are being shaped by people who want to catch up with the fast pace of modern high-tech society. M-learning is just the solution for their requirements. Third, consumers are demanding better and more mobile experiences. As more people gain greater comfort with simple mobile applications like SMS text-messaging and mobile Web-surfing, the greater will be the demand for more mobile services, like MMS(Multimedia Messaging System). In fact, as bandwidth increases and media players like Flash continue to improve users’ experiences, the more rapidly will mo- bile applications continue to increase in number. Compared with traditional e-learning systems, a rich m-learning system should in- clude the following unique attributes, provoked by its mobility. Access: Contrary to e-learning, which supposes always-on connection, m-learning systems can be accessed anytime, anywhere with possible interruptions. Richness: Multimedia educational files like video, sound and animations can be sub- scribed and played in a smooth and seamless manner, and can be presented properly on various mobile devices despites of their small screen size [3]. Interactivity: The system allows mobile users to interact freely with the display and the content. Flexibility: Educational contents designed for use with one kind of mobile device or operating system can be played on other devices with some expectation of compara- ble quality. The system is accessible through different wireless access methods. Security: The interactive mobile devices are protected from malevolent attacks. The shared content and dialogues between educators and learners are protected from being intercepted by unintended recipients [4]. An Optimized Scheme for Mobile Learning on IP-Based Network Using SIP 543 Based on the above studies of m-learning, we can see that the existing architecture of current e-learning systems must be revised to provide more mobility and richness, that’s why we introduce SIP technology into this research. 2.2 SIP Advantages for Mobile Learning SIP is a signal protocol on the application level that is used for managing multimedia sessions between participants on IP-based networks. Approved as an official standard of IETF in 1999, SIP’s popularity has risen recently. Today, SIP applications are in- stalled everywhere, from large-scale mainframes, PC, to small embedded devices like PDA and smartphone. In section 4 of this paper, we will give examples of detailed SIP signal flow on m-learning applications. Here we simply focus on SIP’s advan- tages in constructing mobile applications. 2.2.1 SIP’s Advantages as a Communication Protocol After detailed research and more than two years’ application of SIP, we sum up its advantages as a communication protocol as following five key reasons: First, as SIP is text-based protocol similar to HTTP and SMTP, it is very easy to read and parse the various SIP commands. Compared with binary encoded protocols like RTP [5], SIP is more convenient to be logged and analyzed, thus easier to be implemented. Second, SIP uses ABNF [6] as its protocol grammar. This makes SIP extensible. In fact, SIP has been extended to complete many works today, from sending instant mes- sage, subscribing presence information, to intelligent electric appliance control. Third, the SIP message body is independent of the SIP protocol and can contain anything. For example, SDP [7] is often carried in SIP message body to describe the related media, but if needed, another protocol could easily replace SDP to complete the same function. In many cases such as 3GPP, XML messages are commonly in- cluded in SIP body. Finally, SIP offers various security mechanisms. TLS could be integrated with SIP seamlessly in transport level. In user level, HTTP digest mechanism is used for au- thentication and authorization. 2.2.2 SIP’s Advantages in Mobility Support Commonly, MIP is used to provide terminal mobility for maintaining transport level connections, say, TCP connection, when terminal moves and changes its access point [8] [9]. Unlike MIP, SIP provides excellent personal mobility in higher level by regis- tering a single SIP URI with different transport addresses. This ensures any registered SIP entities be routed regardless of their locations and access methods. SIP also pro- vides service mobility. This means when the SIP agent moves, the SIP service, like a SIP session will be continued [10]. Consider that we will mainly use UDP to carry RTP media stream and SIP signal message, the mobility support by SIP is enough to meet the needs of our system, MIP will not be integrated. For all of the above reasons, we choose SIP as the main protocol to construct our m-learning system. . In: IEEE Internet computing, pp. 14–21 (2003) 13. Kärkkäinen, L., Laarni, J.: Designing for Small Display Screens. In: Proceedings of the 2rd Nordic conference on Human -computer interaction,. multi- media resources included in learning contents is one of our future works. Another primary future work is combining an adaptive content delivering system with our authoring tool that has the. concept of e-learning has been constantly evolved into mobile learning(m-learning), which means to use mobile technologies to enhance the learning experience by blend- ing mobile terminal devices