A Shareable e-Learning Platform Using Data Grid Technology Chao-Tung Yang
Hsin-Chuan Ho
High-Performance Computing Laboratory Department of Computer Science and Information Engineering Tunghai University Taichung City 40704, Taiwan (R.O.C.)
[email protected] [email protected] Abstract Over the past decade, speed in the transmission of knowledge is no longer the way it used to be. Due to this influence, conventional educational methodology has also followed this trend and has gone through a momentous transformation. An excellent example is e-Learning which has achieved and broken through the restrictions of time and space. In recent years it has become one of the most popular teaching methods. SCORM (Sharable Course Object Reference Model) the most popular e-Learning standard has been adapted from many differing e-Learning platforms. Normally, courseware meeting SCORM standards is sharable with other e-Learning platforms. Most e-Learning platforms however are unable to share courseware directly on the Internet. With this in mind, we have employed one type of Grid computing technology called “Data Grid” in order to achieve this. This technology allows the integration of different SCORM platforms into a huge e-Learning environment.
Keywords: e-Learning, Grid Computing, Data Grid, SCORM
1. Introduction With the rapid development in internet technology, along with the gradual improvements found in network bandwidth and quality, real-time transmission of high-quality video and audio has become possible and a true reality. Because of these momentous transitions, conventional methods of school education have also followed this trend. A good example is in e-Learning which has become one of the most popular teaching methods. An increasing number of schools and businesses are setting up e-Learning platforms for their students and employees. Generally speaking, an e-Learning Platform requires an LMS (Learning Management System), to
store and manage the teaching content [1]. The LMS plays two important roles which are, to deliver the desired Courseware when and as needed and also to track the learner’s reactions and responses. However, every LMS platform runs its own learning materials and cannot be exchanged with another LMS. This makes e-Learning resources unavailable for sharing which doesn’t make it very versatile. To deal with the above problem, in late 1997, the U.S. government launched the ADL, (Advanced Distributed Learning Initiative) program [2]. An interactive technical standard, known as SCORM (Sharable Course Object Reference Model), was launched. SCORM aims to establish a mechanism for repeated use and sharing of courseware as a way to reduce time and cost in developing courseware and make courseware be reusable and acceptable in different LMS. Basically, courseware meeting SCORM standards is sharable with other LMS. The problem that now arises is that almost every individual LMS does not have the capability to share courseware directly with another LMS. The main reason is due to the lack of a reliable and handy courseware sharing system. In this research, we have used Grid Computing and Data Grid technology to set up a courseware-sharing platform, where courseware can be reused and shared successfully.
2. Background By way of the Internet and use of appropriate operating systems and software, grid computing bases are the key concept to linking isolated computer resources, such as the computational device, storage device and various I/O devices [3]. When we turn on linked PCs or facilities on the grid, other computers also on the grid will search for components to begin
processing and computing for the relative work required. These computers can be in different organizations or locations. The organizations that form the grid for computing are referred to as “virtual organizations” or “grid organizations”.
2.1. Data Grid Architecture Some newly developed scientific studies such as High Energy Physics and Computational Genomics demand access of large amounts of data which is a requirement that leads to such considerations as data file management, replicated files management, and transfer, and distributed data access management. Data grid architecture is meant to integrate the data storage devices and data management service into the grid environment. In this study, we have adopted a grid middleware called Globus Toolkit [4] as the infrastructure for the data grid. Globus Data Grid comes in two layers. In the Low Level layer are the Data Grid Core Services, and in the Upper Layer are the High Level Components [5]. Figure 1 shows the Data Grid Framework. Replica Selection
Service Replica Management
Service
High level Components Low level Core Services Storage System
Grid Service Infrastructure
Metadata Repository
Service
Resource Management
Service
Figure 1. Data Grid Framework The Storage System is a basic data grid component. It defines all storage technology capability such as adding, deleting, reading, writing and operating file instances [6], such as HPSS, DPSS (Distributed Parallel Storage System). Data Access Service is the setting up of a mechanism for the accessing, managing and transfer of data in the storage system [7].
Metadata Service is for managing and accessing Metadata, which contains Data Grid information. Metadata Application includes files description information and information on data environments. Replica Metadata is applied to manage replication of data objects, and it is a method to help map logical files with physical files. Resource Management schemes are responsible for the storage system, networks and other data grid resources to assure end-to-end efficiency, technical assessment of the efficiency test, as well as the crucial resources. Grid Security Infrastructure (GSI) [8] provides environment authorization and a certification mechanism to a large number of users.
2.2. e-Learning and SCORM standard The SCORM standard is defined into 2 main frameworks; the CAM (Content Aggregation Model), and RTE (Run-time Environment) [9]. CAM produced courseware is based on the principle of being reusable, interoperable and sharable. This main framework comes with three major elements: content model, metadata and content packaging. In content model, the courseware is defined with content objects with the elements being properly arranged before becoming a course for reuse, also known as SCO (Sharable Content Object). The elements in SCO are known as assets (such as html files, graphic files or multimedia files.) Metadata files are used to describe information on the courseware through XML [10]. Through the description of courseware and the elements made by metadata, we can further manage the resources of the course. Content packaging uses the Manifest XML files, denominated as imsmanifest.xml, to arrange and pack SCO as the framework of the course. In conventional e-Learning systems, each of the learning platforms and the courseware had a different method of communication as they had different programs and the API functions were defined differently. In SCORM, the RTE (Run-Time Environment) is built to overcome this communication problem. We viewed RTE as a simple Client-Server relationship. Client end is the browser and the API Adapter is provided by LMS which plays a key role to successful communication between LMS and the courseware. At the same time, it is responsible for relay and reception of information between the Client and the Server.
3. System Architecture 3.1. SCO Repository Based on Data Grid A number of LMS will be used as Data Grid nodes for implementation of a complete Data Grid platform, in which each node will be provided with an interface for linkage between the Grid interface and LMS. After completing the framework of Data Grid, Data Grid is to have SCO shared between nodes. Figure 3 shows a conventional LMS, where we will see that all SCOs are in the SCO Repository. If the learner logs onto LMS for a class, all of the courseware available would be in the Local LMS. Although SCO meets SCORM standard and can be running in every LMS it is still inconvenient sharing SCO between multiple LMS because of the lack of a fast, safe and secure mechanism.
Figure 4. SCO Data Grid Platform
3.2. Data Grid Replica Architecture Within our e-Learning Data Grid, the RLS (Replica Location Service) [11] plays a vital role by providing a comparison feature between logical file names and physical file names. At the same time, Data Grid users are given a convenient interface for saving and loading resources on the Data Grid, alleviating worries of where and how those resources are stored. Figure 5 shows the complete SCO Data Grid structure we intend to accomplish. The bottom-most level is the three physical SCO data base, as illustrated.
Figure 3. LMS and SCO Model In Figure 4, we have an SCO-sharing mechanism based on the Data Grid platform. Each of the SCO Repository in LMS is linked through Globus middleware and each and every LMS node is to share the SCO in other LMS within the Data Grid Interface. As show in Figure 4, we see Globus in the middle of the structure which is the communication channel for other nodes between Local LMS and Grid Organization. The communication between the nodes is then conducted by Grid Portal, which becomes the interface between grid nodes.
Figure 5. SCO Data Grid Structure In the bounds of the Globus structure, the RLS Server is separated into two parts. First, the LRC (Local Replica Catalogs) allow the LFN (Logical File Name) to correspond against the PFN (Physical File Name) on the physical storage system. The other part is
the RLI (Replica Location Indices), which corresponds the LFN against the LRC. In the case where LRC and RLI are installed on different servers, the LDAP is utilized as the communicative protocol between Nodes.
& hardware equipment purchasing expenditure can be saved and the goal of complementation and sharing of resources among schools and different departments can be achieved.
3.3. Data Grid Portal
References
In Grid Organization, Grid Portal serves as a communication with grid members and its main function is to provide the user with a Web-based interface for the use of the services and resources on the grid. Our Data Grid Portal utilizes NMI’s (NSF Middleware Initiative) OGCE Portal [12] as the Grid Portal Site for the whole Grid organization. The OGCE Portal framework provides a general portal architecture that supports the virtual organizations that are comprised of scientists and project developers. The API for the development of reusable, modular components that serve to access the services is being developed within the Grid organization. Figure 6 shows our Data Grid portal Screenshot.
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Figure 6. Data Grid Portal Screenshot
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Conclusion
This research aims to merge the technology of Data Grid with that of SCORM, a step that would allow the independent LMS to share the SCO on the Grid environment. As long as each and every Data Grid has the node duly installed and tested and the SCO meets the SCORM standard, an environment in Grid Architecture for sharing of SCO courseware would be available. In such a case, the LCM suppliers would not have to make courseware which is already available in other Grid Nodes, so as to save on cost and make the best use of present learning resources. On another hand, learners can learn more courses without having to be affiliated with other LMS. A huge amount of software
Bohl, O.; Scheuhase, J.; Sengler, R.; Winand, U.; The sharable content object reference model (SCORM) - a critical review.; Computers in Education, 2002. Proceedings. International Conference on, pp. 950 – 951, December. 2002. [2] Advanced Distributed Learning - Home http://www.adlnet.org/ [3] Fran Berman, Geoffrey, Tony Hey,; Grid computing – Making the Global Infrastructure a Reality,; 2002 John Wiley & Sons Ltd, pp 9-49 ISBN: 0-470-85319-0. [4] Introduction to Grids and the Globus Toolkit http://www.globus.org/training/grids-and-globustoolkit/ [5] Getting Started with the Globus Replica Catalog http://www.globus.org/datagrid/deliverables/repli caGettingStarted.pdf [6] Chervenak, I. Foster, C. Kesselman, C. Salisbury, S. Tuecke.; The Data Grid: Towards an Architecture for the Distributed Management and Analysis of Large Scientific Datasets,; Journal of Network and Computer Applications, Volume 23: pp187-200, 2001. [7] Globus: Grid Security Infrastructure (GSI) http://www.globus.org/security/ [8] Globus: Replica Management http://www.globus.org/datagrid/replica-managem ent.html [9] Heng-Tun Li; Chu-Hung Lin; Yuan-Chun Chang; Jin-Tan David Yang.; On the distributed management of SCORM-compliant course contents.; e-Technology, e-Commerce and e-Service, 2004. pp. 538-539, March 2004. [10] SCORM Version 1.2 Sample Run-Time Environment (RTE) Version 1.2.2 http://www.adlnet.org/index.cfm?fuseaction=rcde tails&libid=738&bc=false [11] Vazhkudai, S.; Tuecke, S.; Foster, I.; Replica selection in the Globus Data Grid.; Cluster Computing and the Grid, 2001. Proceedings. First IEEE/ACM International Symposium on, pp. 106-113, May 2001. [12] OGCE: Open Grid Computing Environment http://www.ogce.org/index.php
