Title is Arial Bold 14 centered - Semantic Scholar

SIGSOFT Software Engineering Notes

Page 1

May 2009 Volume 34 Number 3

Integrating EduLearn Learning Content Management System (LCMS) with Cooperating Learning Object Repositories (LORs) in a Peer To Peer (P2P) architectural Framework Lakshmi Sunil Prakash1, Dr.Dinesh Kumar Saini1, N.S.Kutti2 Faculty of Computing and IT Sohar University1 Department of Computer Science Sultan Qaboos University2 Email: [email protected],[email protected],[email protected] Abstract An attempt is made to integrate the EduLearn Learning Content Management System (LCMS) components with comparable Learning Objects Repository (LORs), specified in Peer to Peer (P2P) architecture to provide a better framework for sharing Learning Objects.

privilege while creating the course objects. The Learners are allowed to interact with the contents of the LCMS during their learning process.

Introduction The advent of internet and its phenomenal growth, has given the sphere of learning several sophisticated automated tools for learning and sharing knowledge. To this extent, Learning Content Management Systems (LCMSs) are fast becoming an integral part of any serious academic or corporate training initiative.

Although there are standards like IEEE LOM, ADL SCORM, or IMS to name just a few, the interchange of educational content between servers or peers is still a problem which has not been solved satisfactorily. [3].

Educational and training organisations need to find the standard means of content manipulation and dissemination. Besides, the Learning Content Designers need to be able to access a suitable volume of Learning objects created is on the rise both in the varilearning object. For this the Learning Object needs to reside in an ety of formats and variety of topics covered. LOR which has the capacity to cater quickly to the needs of the There is a profuse amount of learning content available on the inLearning Content Designer. ternet and the contents are mainly available as collections called Reuse of a Learning Object is possible only if it is available easily Learning Object Repositories (LORs). LORs are mostly isolated and it is designed in a standard format. Such a reusable learning and inaccessible entities which are not able to harness the full object (RLO) has the ability of being reused in different learning power of this digital content. Though this digital content is widely distributed across the network, including large network servers, it contexts and for various objectives. is difficult for Subject Matter Experts, Learning Content Designers We have proposed a new framework for more efficient e-learning and other varieties of users, to acquire the most suitable learning environment by using P2P architecture and Semantic Overlay objects for their subject domain. It is also difficult to search, cusNetwork. This will help in efficient management of LCMS com- tomize and maintain this large volume of information in a standarponents and improve the performance of LCMS through the RLO. dized way. Our framework authenticates Learning Object Repositories and provides a better load balance for the framework using P2P tech- It would be imperative for organizations to share online learning content if the process of Learning Content Generation has to be a nology. profitable process. These content being digital is also generally Keywords: Learning Object Repository (LOR), Reusable Learn- associated with Digital Rights issues. The main aim of integrating ing Object, Peer to Peer (P2P) networks, standardization, Semantic existing LOR into a P2P architectural framework is to provide Overlay Networks(SONs), EduLearn, Learning Content Manage- means for the standardisation of learning content and to enhance ment Systems (LCMS). the reusability of learning content.

In this paper we wish to propose a P2P Architecture for managing the Learning Content stored in various Learning Object RepositoThe EduLearn architecture [1] is an e-Learning prototyping, envi- ries. P2P technology would be able to provide the perfect framronment built by various building elements The EduLearn LCMS work to access such wide spread information on such a network. an LCMS manages the learning content, eases content reusability, E-Learning provides workflow support during content development, and de- The term “e-learning” was defined in alignment with a definition livers content via predefined interfaces and presentation layers by Rosenberg [4]. According to Rosenberg, the first and most im[2,3]. portant feature of e-learning is that it takes place in a networked The Subject Matter Experts (SMEs), Content Designers and In- environment. This means that computer of the learner is in constructors are able to access both LO database and Metadata data- stant communication with a central server. Also e-learning matebase via their respective managers with system level privileges. rials are accessible via an Internet browser on a personal computer. Instructors use Metadata database and LO database with user level

http://doi.acm.org/10.1145/1527202.1527212

DOI: 10.1145/1527202.1527212


Page 2


Learning Object Repository (LOR) / Learning Content Management Systems (LCMS) A Learning Object Repository is an electronic database that keeps a collection of learning objects and provides the essential activities that allows learning object accessibility, use and reuse [13]. Friesen defines an LOR as an online, searchable collection of learning objects [14]. Currently, there is an increasing number of LOR which have been developed and implemented for specific organization, other organization or individual [13]. Learning Management System (LMS, sometimes called Virtual Learning Environments) focus on management of learning services for end users: they are broadly-used [15] [16]. These Learning Content Management Systems (LCMS) store both documents themselves and their associated metadata; they are also called Learning Object Repositories (LOR) [17]. In consequence, a LOR must provide at least some facilities for creating and/or updating RLO metadata, which will be used to provide querying services to Learning Management Systems The advent of e-learning has also affected the way people learn (LMS) and other kind of tools. and communicate in a learning environment, be it a traditional academic institution or in a corporate training setup. Peer to Peer Technology Fig1 – E-Learning System

This as a consequence has created a major change in the way edu- Peer-to-peer systems (P2P) have emerged as a significant social cational materials are designed, developed, and delivered to those and technical phenomenon. These systems provide infrastructure for communities that share CPU cycles (e.g., SETI@Home, Entrowho wish to learn [5]. pia) and/or storage space (e.g., Napster, FreeNet, Gnutella), or that In a typical learning environment, there are several groups of support collaborative environments (Groove). people involved: authors and learners, which are the main players, and administrators and trainers [3]. Authors may be teachers or Two factors have fostered the recent explosive growth of such instructional/learning content designers who create e-learning con- systems: first, the low cost and high availability of large numbers of computing and storage resources, and second, increased nettent by using an authoring system. work connectivity. As these trends continue, the P2P paradigm is Learning Object bound to become more popular. The current generation of instructional design, development and delivery is currently dominated by the instructional technology called the Learning Object [6]. This is due to its potential generativity, adaptability, and scalability [7]. IEEE LOM defines a learning object as “any entity, digital or non-digital, which can be used, re-used or referenced during technology supported learning” [8]. However, the main characteristic of learning objects is its reusability. A reusable learning object (RLO) has the ability of being reused in different learning contexts and for various objectives [9]. The concept of reusable learning object [10, 11] has become the central notion of a new approach to education and organizational learning that emphasizes reusability as the key characteristic. This new approach may eventually results in mass customization [12] and a general improvement in quality and efficiency when designing learning experiences. The challenge for Subject Matter Experts (SMEs), Learning Content Designers (LCDs) lies in their ability to convert topics and subtopics into small granules of Knowledge which can be embedded in the Institution’s Learning Object Repository.

Peer-to-peer systems are distributed systems consisting of interconnected nodes which are able to self-organize into network topologies so as to more efficiently share resources such as content, CPU cycles, storage, and bandwidth. In addition, P2P systems are capable of adapting to failures and accommodating transient populations of nodes while maintaining acceptable connectivity and performance, without requiring the intermediation or support of a global centralized server or authority [18]. Current P2P Architectures for Downloading Learning Objects In a recent work by, Meulpolder et al .,[20] they present the design of TRIBLERCAMPUS, which offers an integration of the BitTorrent-based Tribler peer-to-peer technology with CMSs. The main idea is to equip every participating campus machine with a small and lightweight P2P core, which runs in the background and takes care of the download process of large files when they are requested via the CMS. Due to the P2P technology, all participating computers automati-

http://doi.acm.org/10.1145/1527202.1527212

DOI: 10.1145/1527202.1527212


Page 3


cally contribute bandwidth to the system, thereby hugely boosting learning object. For this the Learning Object needs to reside in an the performance. LOR which has the capacity to cater quickly to the needs of the Learning Content Designer. They also present the results of measurements and trace-based simulations of a prototype implementation of TriblerCampus This is a vital step in Knowledge Management. Knowledge Manbased on the popular open-source CMS Moodle. They show that agement can be thought of as the deliberate design of processes, the performance of TriblerCampus consistently stays high, even tools, structures, etc with the intent to increase, renew, share or when the demand in the system reaches peak levels, and they improve the use of knowledge represented in any of the three discuss the applicability of the system in a distance learning structural, human, and social elements of intellectual capital [19]. setting. The work of Ternier et al., [21] in their paper presents a new archi- There is a large number of LORs but they exist more or less in an tecture for Learning Object Repositories, based on web services. isolated manner catering to the storage and retrieval requirements the mother-institution. As such there are an enormous amount of The goal of our architecture is to facilitate interoperability with LOs existed over the Internet that can be utilized by online learnother repositories and to enable experimentation with new tech- ers or users. Reusable LOs lay down the foundation for large scale niques like Peer-to-Peer and Federated Search. collaboration among educational organizations. LOs developed at different organizations can be used by other organizations, thus This architecture uses two approaches that is the Peer-to-Peer providing high-quality courses to every student. (P2P) and Federated System (FS) Approach to query the Learning Object Repository / Repositories for a particular LO. Currently, there is an increasing number of LOR which have been developed and implemented for specific organization, other organThe EduLearn architecture (can be understood to be based on the ization or individual. Regardless of the huge number of LOR exfollowing scenario. isted, based on the analysis conducted on existing LOR it was discovered that in obtaining a particular learning object stored in every LOR, it would require accessing each LOR separately [2]. Problem Description The LO repository contains contents which are rarely reviewed for Learning Content Management Systems (LCMSs) are fast becom- the quality only a few Learning Object Repositories have any built ing an integral part of any serious academic or training organiza- –in support for quality assessment. tions. They are used to manage course information and to disseminate educational content. The existing facilities and servic- MERLOT [5] has established a peer-review system for learning es of LCMSs can make them an ideal platform for sharing and objects, while CAREO1 provides Wikis2 as a mean to discuss or acquiring digital learning content for teaching and training, within provide comments associated to learning objects. the campus and for distance learning Before organising a learning environment, considering learner An LCMS supports learning content creation, storage and dissemi profiles, arranging learner activities and planning evaluation technation, in an organised way. The main functionalities of an LCMS niques, its’ important to devise a framework for the dissemination, is to allow content authoring, linking and publishing, assembly and reuse of learning content on which this learning environment is repository [13]. However an LMS backed LOR is incomplete, if it based. cannot ensure integrity and volume. In other words, it is an electronic database that keeps a collection of learning objects and pro- Integrating LOR into a P2P Framework Using Sematic Overvides the essential activities that allows learning object accessibili lay Networks (SON) ty, use and reuse [19]. The main aim of integrating existing LCMs into a P2P architecEducational and training organisations need to find the standard tural framework is to provide means for the standardisation of means of content manipulation and dissemination. Besides, the learning content and to enhance the reusability of learning content. volume of Learning objects created is on the rise both in the variAs pointed by Encheva and Tumin [18 ] , large scale collaboration ety of media format and variety of topics covered. between educational organisations can provide high quality courses to their students by reusing LOs. This will enhance the Ideally, a reusable learning object (RLO) has the ability of being profit earning ability of institutions if an audit trail can be proreused in different learning contexts and for various objecduced for each LO in the Learning Object Repository, for billing tives.Reuse of a Learning Object is possible only if it is available purposes. easily and it is designed in a standard format. There are 2 kinds of clustering while building a super peer (1) Peer The onus is now on ensuring the reusability by making each LO tier, Cluster of peers and super peers (2) Super Peer tier among top easily available , easily searchable and ensuring that its contents level super peers. are standard (unique either in content, objective or format) of these Learning objects residing in an educational or training institutions’ There are 2 scenarios possible for implementing the EduLearn Learning Repository. P2P framework, depending on the LOR’s bandwidth and processLearning Content Designers need to be able to access a suitable ing capacity. Either the Edulearn LOR can become a super-peer or

http://doi.acm.org/10.1145/1527202.1527212

DOI: 10.1145/1527202.1527212


Page 4

EduLearn P2P architecture


Figure 2- SON formation with respect to SuperPeers SP0 in EduLearn LOR Figure 1 – EdulLearn Framework

The Semantic Overlay Network (SON) is a flexible network organization that will help us in improving the importance of the EduLearn P2P Framework [24]. In order to increase the query performance we incorporate a flexible network organization called Semantic Overlay Network (SON) [24]. With SON nodes with similar content are clustered together. Whenever a user starts a search for any query string, he is not interested in every single instance of query string. Similar to web search, most of the user are satisfied with the small subset of all matches. SONs exploit this characteristic by trading off the maximum achievable level of recall (i.e., the percentage of the matches that can be found) and the performance of the system [22].

a cluster peer depending on these criteria. EduLearn can act as a super-peer (as it has accessibility to more resources) in the cluster. Super-peers act as local search hubs, building indices of the content files shared by each peer connected to them, and proxying search requests on behalf of these peers. Desirable properties for EduLearn to become super-peers would include accessibility to other peers, bandwidth and processing capacity. The idea is to minimize the search time for LOs and to find the largest number of similar content LOs (sharing the same learning objective, similar key descriptors) to enable quicker Learning Content Design to suit different types learners who have different learning preferences. The LOR in Figure 1 needs to be integrated into the P2P content sharing framework which can be extended in the following manSuper-peers act as cluster leaders and service providers for a sub- ner. set of client peers, providing four basic services to the clients: join, update, leave and query [23]. Once a client - peer (cooperating The Learning Object Repositories depicted in Figure 3, each have LOR) (Figure 2) sends a query to the super-peer, some vital infor- a large volume of digital content that can be shared across a netmation called the peer metric is passed on to the super-peer. It work and the content can be verified by the Edulearn Exconsists of the client peer’s identity (IP address), bandwidth, and port/Import Manager which filters the global LO being transmitted processing power. Once the client peer has joined the network, the between EduLearn LOR from the other organizations’ LOR. client peer is ready to query content in the network, and to allow This filtering mechanism ensures that LOs, that are too identical in other client peers to download content from it. When a client peer content and learning objectives so as to appear as duplicates do not leaves the system, the super-peer removes that client peer’s peer appear in the EduLearn LO Repository. metric and index. If a client peer ever updates its content data, it sends an update message to the super-peer, and the super-peer up- Another mechanism that will be operable by the I/E Manager will dates its index accordingly. When a super-peer receives a query be ensuring that the Global LOs and digital content that are re from its client peer, it matches what is in its index library and for- ceived from the cooperating repositories are grouped together wards the query to its neighbors, who in turn forward it to some of with similar content local Learning Objects within the EduLearn their neighbors, using a suitable super-peer overlay network LO Repository. routing algorithm. Proposed Architecture After results (or timeouts and error messages) are received from all of its neighbors, the super-peer sends the aggregated result to the Here we discuss the main Component responsible for driving the requesting client peer. This content is then indexed in the LORs’ Standardization and reuse of each LO in the EduLearn LOR. This Metadata Repository. component is the I/E Manager. The Export/Import Manager verifies the reusability of the learning object exported by the EduLearn After results (or timeouts and error messages) are received from all LOR. It must be able to track the usage statistics of each LO thus of its neighbors, the super-peer sends the aggregated result to the assisting the Learning Content Designer to receive an up to date requesting client peer. This content is then indexed in the LORs’ account of the interest level in each LO in other organizations’ Metadata Repository. LORs.

http://doi.acm.org/10.1145/1527202.1527212

DOI: 10.1145/1527202.1527212


Page 5


ries, will be similar and even identical in content and hence a large amount of time is required to harvest a select set of LOs that will cover the scope of a particular course. When a request is received from the cooperating LORs from other organizations, the I/E Manager retrieves the most suitable set of LOs for that request using the metadata information existing in the LOR for each LO. However the Metadata in most LORs are not able to give a complete A Learning Content Designer (LCDs) has access to a wide functional description for residing LO. In this case the Peer Meradata file will be able to retrieve the LO that matches the query recollection of LOs for a particular domain. quest keywords received by it from the cooperating LORs or users of EduLearn LMS. However, when the Course Object is prepared from the Another concern is that there is no standard format for an LO, this Course Profile, the local LO (from LOR) that corresponds to results in a problem while cataloging the downloaded LOs in the the Course / Learning Content design, is not able to satisfy the metadata repository [25]. complete requirements of that Learning Objective. A query is then sent, through the LOR interface to the Import / Export Since most metadata in current LO repositories are no more than Manager which contains the keywords corresponding to that an overall content identification and description, this provides LO. limited value from the viewpoint of delegating tasks to agents [11]. The I/E manager will transfer this query to the System Managers of the Cooperating LORs and as soon as similar content The EduLearn Framework has a Metadata Repository which beLOs are received they will be downloaded and sent to Learnhaves like a kind of catalogue information for the large (local or ing Content Designer for verification and selection. distributed) LO-repository. This should make the searching process to be easier and quicker before locating an LO in the repoTo prevent replicated LOs from populating the local LOR, the sitory. In simple form, the metadata can be stored as a simple text I/E Manager will send requests to the system managers of file containing a set of metadata records corresponding the LOs cooperating LORs. This will include metadata information stored in LO-repository. Here, the instructors scan through the about the existing LO residing in its LOR. This will prevent a metadata file manually and identify the required records. This is suitable for only local use. The EduLearn test bed can be used to copy of that LO from being downloaded to the local LOR. test even machine-readable metadata models. The machineThis will help the LOR repository to maintain a unique set of readable metadata needs the collection of the metadata modeling LOs and that will be the first step in standardization process. languages like XML and RDF. The test bed can also be extended a. Also each LOR can be termed as a Topic/Course Peer, to experiment with the implementation of fully semantic-based depending on the nature of LOs in it. This peer will LO model by using ontology [12]). have a Metadata file that will maintain a catalogue like A prototype model of LO metadata may include essentially the information indexing each LO available in it. information such as the title, author name, creation date, technical

The Export/Import Manager component can also track whether the other organization LOR has the requisite authentications to access the learning content in the EduLearn LOR. The I/E Manager needs to have access to information from the Metadata Repository to locate similar content LOs from the cooperating LORs. This situation can be explained as follows 1.

2.

b.

3.

This Metadata file will be updated each time a new LO from the cooperating or peers enters the LOR.

These similar-content LOs need to be clustered under a Course/Topic Peer

requirements, objectives and outcomes, educational context and intent. This can be extended to Standard reference model, LOM (Learning Object Metadata) model released by IEEE 1484.12.12002 [17]. Metadata manager acts as an interface between the users and the metadata database.

LOs received from the cooperating LORs in the framework may be not in a format, identical to the EduLearn LO Format. The MeEach Learning Object Repository will contain several target local tadata must catalog such descriptive data for each LO before and Global LOs. downloading the LO to the EduLearn LOR It is inevitable that a large amount of LOs stored in these reposito-

http://doi.acm.org/10.1145/1527202.1527212

DOI: 10.1145/1527202.1527212


Page 6


The Export / Import Manager • Prevents replication of LOs. • Performs User Authentication. • Maintains LO usage statistics.

•

Assists in

grouping similar Content

Figure 3– P2P Framework for EdulLearn A P2P based E-learning System should provide instructors with a maximum number of LO that belongs to the similar content peers group. This will reduce the search type for harvesting LOs that belong to a particular subject. A Learning Content Designer will then be able to quickly utilize an available set of LOs to construct a topic.

Figure 4– The Flow of events in the EduLearn Learning Object Repository together as topic peers.

Each Learning Object Repository will contain several target local Most theoretical topics do not vary much in content except in and Global LOs. scope; the possibility of reuse of these LOs that cover the scope of the T component is higher. The parent institution will embed the various local LOs into this repository. These LOs will then be used to design courses, required for each academic offering. Each academic program Pi will be defined as a unique set of courses; Courses Ci , Pi = {C1 C2, C3, C4 …Cn}. Each program requires a certain set of credit hours which must be satisfied by completing a set number of courses, Ci . This course Ci = {T1 T2, T3, T4 ………………...Tn} will then be divided into a set number of topics topics Tk., Each topic Tk., may be divided into the following components, the theory components Th, the assessments A, the practical components P, exercises components, E. Tk = {Thn, An, Pn, En}, Subject Matter Expert

While creating P2P for Cooperating LORs , to cluster similar content LOs , harvesting LOs that satisfy the same theoretical requirements or cover the scope of the topic, can be done to create similar content repositories. This will reduce the duplication of Learning Objects LOs in the repository. This cluster of similar content LOs falling under a particular discipline can be grouped

http://doi.acm.org/10.1145/1527202.1527212

Figure 5– Organisation of the EduLearn Elearning Environment

DOI: 10.1145/1527202.1527212


Page 7

T- Model for e-learning environment T model = {LCD, SME, L, CFO, CoLOR, ELO, LO} S=Finite flow of events that describe how something works. F=Finite set of functions/messages O= finite set of operators M=special function that maps operator into operator type, o ∈ O {⊕, n, v, ≤, ≥, ≡, ≠, } A finite set of arcs bidirectional and unidirectional SM-{Learning Content Designer, Subject Matter Expert, Learner, Course Profile Object, Cooperating LORs, EduLearn LOR, Learning Objects} Conclusion In this paper we have chosen a standalone LOR in an e-learning environment can be made more efficient through the restricting of its framework by using P2P architecture and Semantic Overlay Network. This will help in efficient management of LCMS components and improve the performance of LCMS. It is better to authenticate Learning Object Repositories and provide a better load balance for the framework using P2P technology. In formulating this paper it was discovered that rules need to be formulated to cluster similar content Learning Objects downloaded from the Global Cooperating Learning Object Repository. Another research point would be how to cluster Learning Objects with different degrees of aggregation. These points will be the direction for future work. References [1] Kutti,N.S., Khanjari,Z., Sunil L.(2007) ,EduLearn: An e-Learning Architecture for Prototyping Web-Based Learning Systems, EISWT 2007 [2]Chapman, B., & Hall, B. (2001). Learning content management systems: comparative analysis of systems used to construct, organize and reuse "learning objects". Sunnyvale, CA: Brandon-Hall.com. [3]V. Pankratius, O. Sandel, & W. Stucky. Retrieving content with agents in web service e-learning systems. Symposium on Professional Practice in AI, First IFIP Conference on Artificial Intelligence Applications and Innovations (AIAI), Toulouse, France, August 2004, 91-100 [4] Rosenberg, M. J. (2001). E-learning: Strategies for delivering knowledge in the digital age. New York: McGraw-Hill.


[11] Polsani, R., Use and Abuse of Reusable Learning Objects, (2003). Journal of Digital Information, Volume 3 Issue 4 Article No. 164, 2003-02-19. [12]Martinez, M. 2001, Mass customization: Designing for successful learning, International Journal of Educational Technology, 2(2), 21pp. http://www.wcwl.uwa.edu.au/ijet/v2n2/martinez/index.html [Accessed 8 June 2001] [13] Lehman, R. (2007). Learning Object Repositories, “New Directions for Adult and Continuing Education”, Volume 2007Issue113,pages 57-66. [14] McGreal, R (2004), Online Education Using Learning Objects. London: RoutledgeFalmer. p. 59-70. [15] M. F. Paulsen (2003), “Experiences with Learning Management Systems in 113 European Institutions”, Educational Technology & Society, 2003, 6 (4), pp. 134-148. [16 ] K. Green,(2003) “Campus Computing 2003, The 14th National Survey of Computing and Information Technology in American Higher Education”, The Campus Computing Project, 2003. [17] M. A. Sicilia,E. Garca-Barriocanal and S. S´anchez-Alonso (2005) , A Semantic Lifecycle Approach to Learning Object Repositories, In Proceedings of the Advanced Industrial Conference on Telecommunications/Service Assurance with Partial and Intermittent Resources Conference/ELearning on Telecommunications Workshop. [18] S. Androutsellis-Theotokis, D. Spinellis (2004), A survey of peer-to-peer content distribution technologies, ACM Computing Surveys 36 (4)335–371. [19 ] Encheva, S., Tumin. S (2005) . Cooperative Learning Objects in an Intelligent Web-Based Tutoring System. Proceedings of the Advanced Industrial Conference on Telecommunications/Service Assurance with Partial and Intermittent Resources Conference/ELearning on Telecommunications [20] Meulpolder, M., Pijano III, V., Epema, D., & Sips, H. (2007). Tribler Campus:Integrated Peer-to-Peer File Distribution in Course Management Systems. [21] Ternier S., Neven F., Duval E., Leuven K.U., Macowicz M., Ebel N. (2003) “Web services for Learning Object Repositories: a Case Study - the ARIADNE Knowledge Pool System” Poster at The Twelfth International World Wide Web Conference, May 2003 , Budapest, Hungary [online] http://www2003.org/cdrom/papers/poster/p203/WWW2003 Poster.htm [22] J Broisin J., Vidal P., Meire M., Duval E. (2005). Bridging the gap between learning management systems and learning object repositories: exploiting learning context information. ELETE, 2005, Lisbon, 478-483. [23 ] Juan Li, ECSP(2003): An Efficient Clustered Super-Peer Architecture for P2P Networks, Master Thesis, University of British Columbia.

[5] Wiley, D.A. (2000). Learning Object Design & Sequencing Theory, Doctoral Dissertation, Brigham Young University. [6] LTSC. (2000). Learning technology standards committee website [On-line]. Available:http://ltsc.ieee.org/ [7] Urdan, T. A. & Weggen, C. C. (2000). Corporate e-learning: Exploring a new frontier [Online].Available: http://wrhambrecht.com/ research/coverage/ elearning/ir/ir_explore.pdf.

[24] Crespo A., Garcia-Molina.H. Semantic overlay networks for p2p systems. In AP2PC, pages 1–13,2004.” [25] Balatsoukas, P., Morris, A., & O’Brien, A. (2008). Learning Objects Update: Review and Critical Approach to Content Aggregation. Educational Technology & Society, 11 (2), 119-130.

[8] Duval, E. (2002), editor. 1484.12.1 IEEE Standard for Learning Object Metadata. June 2002 [9] Khierbek. A., Salloum .S.,Tannous.A. (2008),”An Inference Network Model for Retrieving Reusable Learning Objects”, IEEE Xplore, Information and Communication Technologies:From Theory to Applications,2008,ICCTA 2008,3rd International Conference on Volume,Issue 7-11 April 2008. [10] D. A. Wiley.(2002) “Connecting learning objects to instructional design theory: A definition, a metaphor and a taxonomy”, The instructional use of learning objects, pages 3–24. Bloomington, Indiana..

http://doi.acm.org/10.1145/1527202.1527212

DOI: 10.1145/1527202.1527212