Toward Design of E-Learning Platform in Grid Environments

Toward Design of E-Learning Platform in Grid Environments Kuan-Ching Li2 Chuan-Ko Tsai1,2 Yin-Te Tsai1 Hsiao-Hsi Wang21 Dept. of Computer Science and Communication EngineeringProvidence UniversityShalu, Taichung 43301 TaiwanE-mail: {g9234052, yttsai}@.tw2 PDPC - Parallel and Distributed Processing CenterDept. of Computer Science and Information ManagementProvidence UniversityShalu, Taichung 43301 TaiwanE-mail: {kuancli, hhwang}@.twAbstractIn recent years, with the rapid development of communication and network technologies, e-learning has been popularized and it became one of the most well-known teaching methods, due to its practicability. However, current e-learning systems present drawbacks. The key problem in present e-learning researches is regarding to ways to support learning systems in scalable, open, dynamic and heterogeneous environments. In this paper, we introduce an e-learning architecture based on grid technology to support learning in distributed environments. A prototype of e-learning platform using grid environment is proposed, built up using a number of open source e-learning softwares in a heterogeneous environment.Index Terms –E-Learning, Grid Technology, Distributed Environments, Open Source.1. IntroductionIn recent years, with the rapid development in communication and network technologies, e-learning has been popularized and become one of the most popular teaching methods in educational community. Along with the gradual improvements found in network bandwidth and quality, real-time transmission of high-quality video and audio has become possible and true reality. Because of these major transitions, conventional methods of school education have also followed this trend.E-learning utilizes electronic devices to assist the education or training process, taking advantage of the internet or any other communication channel to connect other devices, to deliver information and knowledge. This model of learning has many advantages with respect to traditional models: a better interaction between the learner and the learning resources he uses, i.e., the learning is not passive; learning can happen anytime and anywhere, i.e., there are not boundaries tied to time and place; a tutor, or learner himself, is able to monitor the progress and to customize the learning experience basing on learner skills and preferences [2].Though, there are some drawbacks related to current learning solutions. First, they are mainly focused on the content delivery, leaving in the background the collaborative view. Second, current learning platforms only support a specific learning-domain and are not able to support learning in different domains [2]. Third, many e-learning platforms and systems have been developed and commercialized. These are based on client-server, peer-to-peer, and web service architecture, their limitations in scalability, availability, and distribution of computing power as well as storage capabilities [10]. Along with these drawbacks, we present an e-learning architecture based on grid technology to solve current e-learning platform problems.In e-learning research, it is a crucial problem the support of learning in scalable, open, dynamic and heterogeneous environments. The scenario is a large scale and connected environment of learning management systems, learning content management systems and virtual classroom systems of different organizations.Grid computing has emerged as an important new field, distinguished from conventional distributed computing by its focus on large-scale resource sharing, innovative applications and, in some cases, high-performance orientation [1]. Grid technology address issues related to access provisioning coordinated resource sharing and problem solving in dynamic, multi institutional virtual organization [9].By adopting grid technology, it is possible a wide-scale learning resource sharing in heterogeneous and geographically distributed environments, the implementation of learning organizations in which different actors (teachers, learners), sharing a common target, are able to cooperate to obtain a result.The remainder of this research paper is organized as follows. In section 2, we introduce generic learning management system, and concepts of grid computing and web services. In section 3, it is discussed the proposed e-learning grid architecture, while in section 4, we present our e-learning platform prototype. Finally in section 5, some conclusions and future works are presented.2. Background2.1 E-Learning SystemsGeneral e-learning systems have four components: People, Authoring System, Run-Time System, and Learning Management System (LMS), as shown in Figure 1 [10]. People in these systems are the learners and authors, while others may include trainers and administrators. Authors (which may be teachers or instructional designers) create content, which is stored under the control of a LMS, and typically in a database. Existing content can be updated, and it can also be exchanged with other systems [3][4].A LMS is managed under the control of an administrator, and it interacts, with a run-time environment which is addressed by learners, who in turn may be coached by a trainer. These components of an e-learning system can be logically and physically distributed. In order to make such a distribution feasible, standards such as IMS and SCORM have been proposed, to ensure plug-and-play compatibility [5][7].An e-learning platform requires an LMS, to store and manage the teaching content. It is a collection of e-learning tools available through a shared administrative interface. A learning management can be thought as the platform in which online courses or online components of courses are assembled and used from. Hall 0 defines an LMS as: “Software that automates the administration of training events. All Learning Management Systems (LMSs) manage the log-in of registered users, manage course catalogs, record data from learners, and provide reports to management.”Figure 1. Generic View of Learning ManagementSystems.2.2 Grid ComputingThe grid computing paradigm essentially aggregates the view on existing hardware and software resources. The term Grid is chosen as an analogy to a power Grid that provides consistent, pervasive, dependable, transparent access to electricity irrespective of its source [8][9].The concept of Grid computing focuses on resource sharing, which is not primarily file exchange, but rather direct access to computers, software, data, and other resources, as is required by a range of collaborative problem-solving and resource-brokering strategies emerging in industry, science and engineering.This description of Grid architecture identifies requirements for general classes of component. The result is an extensible, open architectural structurewithin which can be placed solutions to key user requirements. The architecture is organized into component layers, as shown below. Components within each layer share common characteristics, but can build on capabilities and behaviors provided by any lower layer. The architectural description is high level and places few constraints on design and implementation. The layered Grid architecture and its relationship to the internet protocol architecture are shown in Figure 2.The Grid Fabric layer contains the resources that are to be shared. This could include computational power, data storage, sensors etc. This sharing is controlled by Grid protocols but the resource could include local networks. In this case, the local protocols take over at this point. The Grid system is just concerned with access above this point.The Connectivity layer contains the communication and authentication protocols required for Grid-specific network transactions. Communication protocols enable the exchange of data between different Fabric layer resources. Authentication protocols build on communication services to provide secure mechanisms for verifying the identity of users and resources.The Resource layer uses the communication and security protocols of the Connectivity layer to control the secure negotiation, initiation, monitoring, control, accounting, and payment of sharing operations on individual resources. Resource layer protocols call Fabric layer functions to access and control local resources. Resource layer protocols are concerned entirely with individual resources.While the Resource layer is focused on interactions with a single resource, the Collective layer contains protocols and services that are global in nature and capture interactions across collections of resources. Collective components are designed that they implement a wide variety of sharing behaviors without placing new requirements on the fabric resources being shared such as: A directory service may allow users to query for resources by name or by attributes such as type, availability, or load.The final layer in the Grid architecture comprises the user applications. Applications are constructed in terms of, and by calling upon, services defined at each layer in the Grid structure. At each layer, well-defined protocols provide access to some useful service: resource management, data access, resource discovery, and so forth. At each layer, protocols and services are used to perform desired actions.Figure 2. The Grid architecture.2.3 Web ServicesWeb services define a technique for describing software components to be accessed via internet, a communication media between different platforms. Web services standard is defined within the W3C, that has the support of large number of industries, and the components interact between in the service processes that are based on XML, SOAP, WSDL and UDDI. The architecture of Web services standard is shown in Figure 3 [12].Figure 3. Web services architecture.Web services are described by XML that covers all the details that is necessary to interact among services, including message formats, transport protocols and location. Simple Object Access Protocol (SOAP) provides a means of messaging between a service provider and a service requestor. It is independent of underlying the transport protocol. SOAP can carry on HTTP, FTP and SMTP. WSDL is a XML-basedlanguage to describe a Web service how to access them, to provide a formal framework to describe services in terms of protocols servers, ports and operations that can be invoked, the specification that provides a SOAP binding which is the most natural technology to be used for implements a Web Services. Universal Description, Discovery and Integration (UDDI) provides the registry and search mechanism for Web services. Concisely, WSDL describes the format SOAP messages, and UDDI serves as a discovery service for the WSDL descriptions.The Grid emphasizes the usage of Web services, and it does not use SOAP for all communications. If needed, alternate transport can be utilized, for example to achieve higher performance or to be able to collide with a specialized network protocols.One critical point is on how to combine the different heterogeneous resources in Grid. XML-based metadata is a popular problem solving, so it has been widely used. The XML document can not only help manage facilities, but also interchange between different databases. The interface based on Web services can integrate not only the web resources easily, but also make the occurrence much faster to duplicate. The process of duplication becomes much easier, since it is based on the open structure of web service.3. Proposed E-Learning Grid Architecture The architecture contains five layers from bottom to up, as shown in Figure4. The infrastructure layer, at the lowest layer, supports basic networking environment, including computing devices, networking and networking protocols etc. Secondly, the basic service oriented architecture for implementing the basic web services related protocols such as XML, UDDI/SOAP/WSDL etc. This layer provides the elementary connectivity, interoperation, reliability and flexibility for the layers on top of it. As next layer, the grid middleware layer is the core of the architecture where the basic grid problems such as distribution, dynamic, open and cross-organization are resolved. The content layer is on top of grid middleware layer to store all of learning contents in our platform. At last, the learning grid portal supports single user sign on the system. In next subsections, brief introduction of these layers will be discussed.Figure 4. A E-Learning Grid Architecture.3.1 Grid Middleware LayerThis layer is a crucial layer to build a grid environment and should be on existing OGSA compliant middleware such as Globus Toolkit 4 (GT4). The Globus project provides open source software toolkit that can be used to build computational grids and grid-based applications [11]. It allows sharing of computing power, databases, and other resources securely across corporate, institutional and geographic boundaries without sacrificing local autonomy. It implements services for Resource Management, Information Services and Data Management in the Grid. The main functions of them are listed below: It enables single sign-on, authorization and security mechanism based on the Grid Security Infrastructure (GSI).3.1.1 Resource Management:Grid resource management involves the coordination of a number of components, including resource registries, staging of executable files, discovery, monitoring, allocation, and data access. The Globus toolkit includes a set of components to help users havea standard set of interfaces for the coordination of the above activities. Grid Resource Allocation and Management (GRAM) is used for allocation of computational resources and for monitoring and control of computation on those resources. GRAM provides a set of standard interfaces and components to collectively manage a job task, and to provide resource information including job status and resource configuration.3.1.2 Information ServicesInformation services have to fulfill the following requirements: a basis for configuration and adaptation in heterogeneous environments; uniform and flexible access to static and dynamic information; scalable and efficient access to data; access to multiple information sources; decentralized maintenance capabilities. The monitoring and Discovery Service (MDS) provides a uniform framework for discovering and accessing configuration and status information such as compute server configuration, network status, and the capabilities and policies of services.3.1.3 Data ManagementThe data management services provide standard means for helping to manage the Grid computing environment. GridFTP is a standard extension to the normal FTP (File transfer Protocol) that works with the Grid Computing data requirements. This is a high-performance, secure, reliable, data transfer protocol that is optimized for high bandwidth across wide area networks. This is a standard that provides GSI security, parallel transfer capabilities, and channel reusability.Replica management service in grid middleware layer provides guarantee for better quality of resource sharing, which implements functions of transparent data transfer/copy, transparent copy selection in grid. The Replica Location Service (RLS) maintains and provides access to mapping information from logical names regarding data items to target names. These target names may represent physical locations of data items, or an entry in the RLS may map to another level of logical naming for the data item. The RLS is intended to be one of a set of services for providing data replication management in grids. 3.2 Content Repository LayerThis layer is on top of grid middleware layer to store all of contents in our platform. As above mentioned an e-learning system needs a Learning Management System to store and manage its teaching content. However, every LMS platform runs its own learning materials, which cannot be exchanged with those of other LMSs. To deal with this problem, the U.S. government launched the Advanced Distributed Learning Initiative (ADL) [6] is unifying e-learning specifications emerging from the international standards organizations into a single specification referred to as the Sharable Content Object Reference Model (SCORM). SCORM aims to establish a mechanism for repeated use and sharing of courseware as a way to reduce the time and cost of developing courseware and to make courseware reusable and acceptable to different LMSs.The SCORM standard is divided into 2 parts: the Content Aggregation Model (CAM) and Run-time Environment (RTE). CAM-produced courseware is based on the principles of reusability, interoperability, and shareability, and it includes three major modules: content model, metadata, and content packaging. Courseware elements are defined as content objects in the content model and must be properly arranged to make a reusable course, also known as an SCO (Sharable Content Object). SCO elements, such as html files, graphic files, and multimedia files, are known as “assets.” Metadata files describe courseware information using XML. The description of courseware and elements made by metadata enables further management of course resources. Content packaging uses the Manifest XML files, denominated as imsmanifest.xml, to arrange and package SCOs in a course framework.Some LMSs will be used as learning grid nodes when implementing a complete learning grid platform in which each node is provided with an interface for linkage between the Grid interface and the LMS.Although an SCO meets the SCORM standards and can be run in every LMS, it may still be inconvenient for sharing among multiple LMSs because of the lack of a fast, safe, and secure mechanism. Each SCO Repository in the LMS is linked through Globus Middleware, and each and every LMS node can share SCOs with other LMSs. Based on Grid Middleware Globus which is in the middle of the communicationbetween nodes is conducted via the Learning GridPortal, which is the interface between grid nodes.3.3 Learning Grid PortalLearning grid portal is the unified entry for all grid platform users. Users from different organizations who logon it could share learning resources without knowing where they come from.4. Prototyping the E-learning platform4.1 Execution flow of a learning platform in GridIn this section, we want to describe the main execution flow of a learner utilizing the proposed learning platform, as also briefly shown in Figure 5.(1) A learner enter the grid portal, the grid portal havea user database which store user information andaccess rights. When a user wants to enter the grid environment, the system will checks the user’s login name and password against the values stored in the database,(2)If the login was successful, the system will show alist of all resources currently available in the grid and the status and type of all resources in the grid.It then requests from each computer (if each computer has it own LMS) some status information (e.g., unused storage space, how many learning content),(3)Furthermore, a broker is assigned which canhandle requests to distribute computation or data across other computers in the grid,(4)For the distribution of data it uses the GridFTP toaccess the other computer’s resource,(5)For the resource have a high speed accessperformance, Replica Location Service supports multiple locations for the same file throughout the grid.4.2 E-learning platform PrototypeIn our learning grid platform, GT4 was installed on each site. Three different versions of open source Learning Management Systems have been installed in these sites in our grid platform: ILIAS is installed in site A, Claroline in site B, while Dokeos in site C. The Grid Portal has been developed using GridSphere in OGCE Release 2 [18].Figure 5. Execution flow of a learner utilizinge-learning platform.Figure 6. Prototype of the Learning Grid. ILIAS [13] is a powerful web-based learning management system that allows users to create, edit and publish learning and teaching material in an integrated system with their normal web browsers. Tools for cooperative working and communication are included as well. ILIAS is available as open source software under the GNU General Public License (GPL). Universities, educational institutions, privateand public companies, and every interested person may use the system free of charge and contribute to its further development. ILIAS is the first free software LMS that has reached SCORM 1.2 Conformance Level LMS-RTE3 and therefore guarantees platform independent re-use of contents [14]. Due to a modular and object oriented software architecture; ILIAS allows easy customizing of the platform for specific purposes.Claroline [14] is a free application based on PHP/MySQL allowing teachers or education organizations to create and administrate courses through the web. Developed from teachers to teachers, Claroline is built over sound pedagogical principles allowing a large variety of pedagogical setup including widening of traditional classroom and online collaborative learning.Dokeos [15] is an Open Source e-learning and course management web application translated in 34 languages and helping more than 1.000 organizations worldwide to manage learning and collaboration activities.The NSF Middleware Initiative’s (NMI’s) OGCE portal provides access to Grid technologies through sharable and reusable components [16]. In addition, the GridSphere portal framework provides an open-source portlet based Web portal [17]. With the GridPortlets Web application, users upload their Grid credentials and use them to gain access to a variety of Grid services.We plan to place multimedia educational materials with different contents in each site. For instance, site A could be used for English teaching materials, site B for chemistry related materials, while site C for bioinformatics related materials.5. Conclusion and future workIn this paper, we have proposed architecture for e-learning platform based on grid technology. In a learning grid environment, learner can learn in scalable, open, dynamic and heterogeneous environments. At present, most e-learning environment architectures use single computers or servers as their structural foundations. The innovative e-learning architecture is presented; as it can solve current e-learning platform problems.To make resources in the learning grid platform available to users, we have to setup a Grid Portal, which is in its preliminary version at the present stage of investigation. We intend that this platform may enable people to process interactions and opinion exchanges through video and audio simultaneously, in situations such as training, teaching, conference and seminar, among others. AcknowledgementsThis research is supported by National Science Council (NSC), Taiwan, under grants NSC94-2213-E-126-005, NSC94-2218-E-126-001 and NSC94-2218-E-007-057, National Center for High Performance Computing (NCHC) - Grid Operation Center, Taiwan, and Providence University Grant.References[1] B. Hall, “New Technology Definitions”,retrieved August 5, 2003 from/public/glossary/index.htm, 2003.[2]I.Foster, C. Kesselman, and S. 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